American Journal of Respiratory Cell and Molecular Biology

Asthma is characterized by immunoglobulin (Ig) E production, infiltration of the respiratory mucosa by eosinophils (EOSs) and mononuclear cells, and bronchial hyperresponsiveness (BHR). Interaction of CD40 on B cells and antigen presenting cells, with its ligand (CD40L) expressed transiently on activated T cells, is known to augment both T cell–driven inflammation and humoral immune responses, especially IgE production. Considering both the prominent role of inflammation in asthma and the association of the disease with IgE, we hypothesized that CD40–CD40L interactions would be important in pathogenesis. To test this hypothesis, we subjected wild-type (WT) mice and animals lacking either CD40 or CD40L to repeated inhalation of Aspergillus fumigatus (Af  ) antigen. Af–treated WT mice displayed elevated IgE levels, bronchoalveolar lavage and pulmonary tissue eosinophilic inflammation, and BHR. IgE production was markedly suppressed in both the CD40 − / − and CD40L − / − strains. However, pulmonary inflammation did not appear to be inhibited by either of these mutations. Paradoxically, development of BHR was prevented by the lack of CD40L but not by the absence of CD40. We conclude that CD40/CD40L interactions, although critical in the induction of IgE responses to inhaled allergen, are not required for the induction of EOS-predominant inflammation. CD40L, but not CD40, is necessary for the development of allergen-induced BHR.

Asthma is a chronic respiratory disease with characteristic pathophysiologic features including eosinophilic and lymphocytic peribronchial inflammation, bronchial smooth-muscle hypertrophy and hyperreactivity, and typical clinical features of episodic dyspnea with an obstructive pattern on pulmonary function testing (1, 2). Numerous genetic and environmental factors are thought to play a role in the pathogenesis of the disease (3, 4). A number of cell types and molecular mediators, including lymphocytes, mast cells, eosinophils (EOSs), immunoglobulin (Ig) E, and cytokines, are thought to contribute to the pathophysiology of asthma.

Abundant evidence exists that T cells have an important role in asthma pathogenesis. In murine models of asthma, passive transfer of T cells confers sensitivity to allergen and eosinophilic inflammation (5, 6). Allergen-stimulated T cell– deficient mice fail to develop airway hyperresponsiveness (AHR) (7-9). In several mouse asthma models, pharmacologic ablation of T cells, neutralization of T-cell growth factors, or interference with T-cell stimulatory pathways has abrogated asthma-like pathophysiology, including eotaxin expression and subsequent EOS influx (7, 10-12).

CD40/CD40 ligand (CD40L) interaction is important in a number of the cellular interactions that give rise to inflammatory responses (13-16). After allergen encounter, responding T cells express CD40L and can then engage CD40 on B cells, monocytes, dendritic cells, and epithelial cells. In the case of B cells, the CD40/CD40L interaction is critical for activation and for the induction of isotype switching (17). Binding of CD40 on monocytes results in the production of proinflammatory cytokines and nitric oxide (18, 19). Lymphocytes from CD40–deficient (CD40 −/−) mice are inefficient at inducing interleukin (IL)-12 production by macrophages, and consequently these animals are deficient in the generation of T-helper 1 T-cell responses critical in the induction of tissue inflammation (20, 21). CD40/ CD40L signaling may be bidirectional. It has been reported that stimulation of CD40L on the surface of T cells by CD40 results in their activation (22).

To examine the role of the CD40/CD40L interaction for the development of allergic pulmonary inflammation and bronchial hyperresponsiveness (BHR), we subjected CD40 −/− mice or mice deficient in CD40L (CD40L −/−) to repeated challenge with Aspergillus fumigatus (Af ). IgE levels, bronchoalveolar lavage (BAL) fluid (BALF) cytology, pulmonary histology, and bronchial responsiveness were evaluated in the treated mice. As expected, CD40 −/− and CD40L −/− animals were unable to mount IgE responses. However, both CD40 −/− and CD40L −/− mice sensitized with Af developed striking BALF eosinophilia and the extent of pulmonary inflammation was the same in mutant and wild-type (WT) mice. Mice deficient in CD40 also developed BHR; in contrast, CD40L −/− mice did not develop a significant increase in bronchial responsiveness after Af stimulation. The CD40/CD40L interaction thus is required for IgE responses but unnecessary for EOS influx and inflammation. CD40L, but not CD40, appears to be required for the induction of BHR.

Reagents and Mice

A mixture of culture filtrate and mycelial extracts of Af (kind gift of Greer Laboratories, Lenoir, NC) was diluted to 2 mg/ml. CD40-deficient mice were derived as previously described and maintained on a hybrid 129/C57BL/6 background (13). CD40L-deficient mice and B6/129 F2 WT control mice were obtained from Jackson Laboratories (Bar Harbor, ME). Mice were housed in a viral antigen–free facility.

Sensitization of Mice

Mice were sensitized as previously described (23). Briefly, they were lightly anesthetized by methoxyfluorane (Metofane; Mallinckrodt Veterinary, Inc., Mundelein, IL) inhalation, and 50 μl of Aspergillus antigen (Af  ) or 50 μl of saline (NS) was applied to the left naris with the mouse in the supine position. After instillation of the Af or NS, mice were kept prone until alert. Mice were immunized three times a week for 3 wk and studied 12 h after the last dose.

Quantification of Serum IgE Levels

Serum IgE levels were determined by enzyme-linked immunosorbent assay (ELISA) as described in the PharMingen protocol, using clone R35-188 antibodies for coating and clone R35-72 antibodies for detection.

Pulmonary Function Measurements

Pulmonary conductance (Gl) was monitored in anesthetized, ventilated mice in a whole-body plethysmograph as previously described. The output signals from eight to 10 consecutive breaths were analyzed using a computerized cross-correlation method. For measurement of methacholine (MCh) responsiveness, a series of increasing doses of MCh ranging from 3.3 to 3,300 μg/kg were each infused in a volume of 1 μl/G body weight via a jugular venous catheter over 4 to 5 s. The maximally reduced Gl values measured after each Mch dose were expressed as percentages of the value measured immediately before administration of that dose.

Collection of Specimens

BAL was performed with a single aliquot of 0.8 ml of phosphate-buffered saline containing 10% fetal calf serum and 1 mM ethylenediaminetetraacetic acid, which was infused into the lungs via the tracheotomy tube and then retrieved. BALF leukocyte counts were determined using a hemocytometer. The leukocyte differential was determined by cytocentrifugation of BAL specimens followed by staining with Diff-Quik (Baxter, Miami, FL). The absolute EOS count was derived as the product of the leukocyte count and the EOS fraction on differential.

Histologic Analysis

Lungs were fixed in 10% formalin under mild vacuum. Sections, 5 μm thick, were prepared and stained with hematoxylin and eosin (H&E). A previously described grading scheme was used to assess the intensity of the inflammatory infiltrate in NS- and Af-treated animals (23). Lungs that showed no focal inflammation or peribronchial or perivascular inflammatory infiltrates were scored as grade 0. Those that showed one or two centrally located microscopic foci of inflammatory infiltrate were graded as 1. In grade 2 lungs, a dense inflammatory infiltrate was seen in a perivascular and peribronchial distribution originating in the center of the lung and extending along the vessels and bronchi into the middle third of the lung parenchyma. In grade 3 lesions, the perivascular and peribronchial infiltrates extended to the periphery of the lung approaching the visceral pleura. Grading was performed by a pathologist (M.R.) unaware of the genotype or sensitization status of the mice.

Allergen-Driven IgE Production in WT, CD40 − / − , and CD40L − / − Mice

We and others have previously shown that intranasal application of protein extracts of the mold allergen Af elicits strong IgE responses in mice (23-25). Because CD40/ CD40L interaction is believed to be critical in the induction of Ig isotype switching in B cells, we sought to determine whether the IgE response would be attenuated in mutant mice. IgE levels were measured by ELISA in sera from Af- and NS-treated animals. Af treatment induced a rise from 436 to 2278 ng/ml in one group of WT B6/129 mice and from 465 to 2130 ng/ml in the second set of WT mice (Figure 1, WT/Af ). No IgE was detected in the sera of either NS- or Af-treated CD40 −/− or CD40L −/− animals (Figure 1, CD40 −/− Af and CD40L −/− Af ). Thus, CD40 and CD40L are each required for the normal IgE response to inhaled allergen.

BALF Eosinophilia in Allergen-Treated WT and Mutant Mice

Because CD40/CD40L interactions have been shown to be important in the induction of a wide variety of inflammatory responses, we wished to determine their role in allergen-driven EOS-predominant inflammation of the airways. EOS influx was assessed both in BALF and in tissue sections. Af-treated WT mice had airway eosinophilia nearly three orders of magnitude higher than did NS-treated WT animals (mean 8.52 × 105 versus 8.40 × 102 EOSs/ml, respectively) (Figure 2A). Similarly, CD40 −/− mice treated with Af had BALF eosinophilia almost three orders of magnitude greater than did CD40 −/− animals treated with NS (mean 1.44 × 106 versus 3.88 × 103 EOSs/ ml, respectively). Af-treated CD40L −/− mice also displayed a similar degree of BALF eosinophilia (Figure 2B), with a mean of 1.01 × 106 in the Af group and 1.48 × 103 EOSs/ml in NS-exposed mice.

Allergic Inflammation of the Lungs in WT, CD40 − / − and CD40L − / − Mice

The extent and anatomic distribution of allergic inflammation was further examined by histologic analysis (Figure 3). Intense inflammation was evident in the lungs not only of Af-treated WT mice but also in CD40 −/− and CD40L −/− mice subjected to allergen inhalation. The nature of the infiltrate was similar in all groups and involved an admixture of EOSs and mononuclear cells surrounding the bronchi with some epithelial damage. Some perivascular inflammation and infiltration of the air spaces were evident as well.

To quantitate the degree of inflammation present in the lungs of Af-treated mice of the three genotypes, we applied a previously described scoring system (see Materials and Methods) based upon both the intensity of the infiltrate and its anatomic extent toward the visceral pleura (23). There were no significant differences in scores obtained for Af-treated WT (mean 2.46 and 2.55 in separate experiments), CD40 −/− (mean 1.93), or CD40L −/− (mean 1.90) mice (Figure 4). Together, the histologic examinations and the BALF eosinophil counts provide strong evidence that allergen-driven recruitment of EOS to the airways can occur by CD40/CD40L-independent mechanisms.

Pulmonary Function Studies

The induction of bronchial inflammation and BHR by allergen appears to be linked both in human asthmatics and in mouse models of the disease. We first determined whether absence of CD40 or CD40L affects the degree of airway responsiveness to intravenous MCh in naive mice by comparing the responses of sham-sensitized WT mice with those of sham-sensitized CD40 −/− or CD40L −/− mice. We found that the lack of CD40 was associated with a reduction in responsiveness to MCh, assessed in terms of Gl (P < 0.001, analysis of variance [ANOVA], Figure 5). Mice lacking CD40L exhibited smaller responses to MCh than did sham-sensitized WT mice only for the highest three doses (maximal responses, P < 0.02, t test, Figure 6). It therefore appears that the presence of CD40 and, to a lesser extent, CD40L is associated with heightened airway responsiveness even in the absence of experimental antigenic stimulation.

We also determined whether the absence of CD40 or CD40L would prevent the development of AHR after Af antigenic stimulation. Significant BHR developed in Af-exposed WT mice and a similar degree of BHR was detected in mice lacking CD40 (Figure 5, P < 0.001, ANOVA). In contrast, Af exposure in mice lacking CD40L did not induce detectable BHR (Figure 6). Thus, CD40L, but not CD40, was required for the development of BHR, even though both proteins were required for the development of an IgE response and neither protein was required for the development of antigen-induced bronchopulmonary eosinophilia.

Studies in humans have identified pulmonary eosinophilia and cholinergic BHR as hallmarks of asthma. We used an established murine model of asthma in which pulmonary eosinophilia and BHR develop in response to intranasal sensitization with Af to test the hypothesis that CD40 and CD40L are essential for these responses to allergen. We found that although IgE was undetectable in serum of CD40 −/− and CD40L −/− mice, Af-sensitized CD40 −/− and CD40L −/− mice developed high levels of BALF eosinophilia and dense eosinophilic infiltrates similar to those observed in WT mice. Paradoxically, development of allergen-induced BHR was prevented by the absence of CD40L but not by the absence of CD40.

The failure of CD40 −/− and CD40L −/− mice to produce an IgE response to antigen is consistent with the previous observations of others (13-15) and reflects the critical roles of these molecules in Ig isotype switching to IgE. B cells must receive two signals in order to make IgE. The first is provided by the cytokines IL-4 and IL-13. The second signal is generated when CD40L, which is induced on the surface of T cells after antigen exposure, binds to CD40 on the B-cell surface. Thus, the absence of either member of this receptor–ligand pair interrupts an essential signaling event for IgE production and neither CD40 −/− nor CD40L −/− mice generate IgE in response to inhaled allergen.

In addition to stimulating Ig isotype switching to IgE, CD40 and CD40L are involved in the pathogenesis of inflammation. Several inflammatory disease processes, including murine lupus, collagen-induced arthritis, and experimental allergic encephalitis, are interrupted by blockade of the CD40/CD40L pathway, implicating this receptor– ligand pair in the pathogenesis of inflammation (26-28). CD40/CD40L appears to be involved in pulmonary inflammatory responses as well, including responses to hypoxic stress and radiation (29, 30). The intranasal administration of soluble CD40L leads to a neutrophilic and mononuclear pulmonary infiltrate in WT but not CD40-deficient mice (31, 32).

Two groups have previously reported pulmonary responses to allergen in CD40 −/− and CD40L −/− mice, with disparate results. Our findings, using CD40 −/− mice, are in agreement with those of Hogan and colleagues who found that ovalbumin (OVA)-stimulated CD40 −/− mice had levels of BALF eosinophilia and BHR similar to those of WT mice (33). In contrast, Lei and colleagues found that OVA-stimulated CD40L −/− mice developed less BALF eosinophilia than did WT mice (34); pulmonary physiology was not assayed. These authors postulated that the difference between their findings in CD40L −/− mice and those previously reported by Hogan for CD40 −/− mice might be related to dosages of antigen. Our results suggest that the levels of BALF eosinophilia are similar in the two types of knockout (KO) mice treated with the same sensitization protocol and that the levels are not significantly less than those observed in WT mice for either KO group.

We believe that the discrepancy between our results and those of Lei and associates (34) regarding the role of CD40L in the generation of airway eosinophilia after allergen exposure may have arisen either from differences in the allergen used or from distinct mechanisms of antigen sensitization. The protocol of Lei and coworkers (34) involved intraperitoneal priming with OVA in the presence of the adjuvant, alum. It is possible that allergen encounter at serosal surfaces and/or in the presence of alum drives an immune response via cellular interactions that are CD40L-dependent. In contrast, Af, the antigen used in our study, elicits a vigorous hypersensitivity response after airway exposure alone. It is a significantly more potent allergen than OVA, driving 10-fold greater increases in BALF eosinophilia (unpublished observations). Thus, the generation of equivalent pulmonary eosinophilic inflammation in the absence or presence of CD40L in our study may be related either to the mucosal pathway of sensitization or to the relatively greater potency of Af.

Despite the overall similarities in IgE and eosinophilic responses to allergen between the two types of mutant mice examined, we observed two differences in the physiologic responses of CD40 −/− and CD40L −/− mice. First, the sham-stimulated CD40 −/−, but not the CD40L −/− mice, were significantly less responsive to Mch than were the WT mice. The reason for this relative hyporesponsiveness of CD40 −/− mice not subjected to experimental allergen exposure was not clear. It is possible that low-level antigenic stimulation by resident microflora or nonspecific irritants could maintain some level of bronchial responsiveness via a CD40-dependent mechanism. Alternatively, the expression of CD40 per se on airway epithelial cells, monocytes, and macrophages could have effects on their function even in the absence of its interaction with CD40L. Such a cell-autonomous effect on cellular function could perhaps lead to a basal rate of production of factors that enhance airway responsiveness. There is also a remote possibility which cannot be easily excluded that there were differences among the mice in the expression of genes unrelated to CD40 and CD40L. Because these mice were derived by targeted mutagenesis, and because we used large numbers of experimental mice along with equivalent numbers of mice of the appropriate genetic background, we believe it highly improbable that other genes relevant to the inflammatory response were affected.

The second difference between the physiologic responses of CD40 −/− and CD40L −/− mice was that the Af-stimulated CD40 −/−, but not the CD40L −/− mice, developed enhanced airway responsiveness compared with sham-stimulated mice. Thus, CD40L is essential for the development of antigen-induced BHR, even though it is not required in the generation of eosinophilic pulmonary inflammation. One possible explanation for the requirement for CD40L in the induction of BHR is that the CD40L molecule itself modulates the function of T cells independent of CD40 binding. An alternative explanation is that, in addition to CD40, CD40L can interact with an alternative partner on other cells, including EOSs, thereby inducing BHR. Our results using the CD40L −/− mice again demonstrate that an influx of EOSs into the airways may not be sufficient for the development of BHR. We have previously shown that mice of certain strains (35) develop marked airway eosinophilia with little or no shift in airway responsiveness after antigenic stimulation; perhaps those animals, like the CD40L −/− mice in the current study, fail to induce those EOSs to release mediators necessary for the induction of BHR.

It has recently been postulated that there are two parallel pathways that can lead from antigenic stimulation to BHR. The first involves production of antigen-specific IgE and perhaps IgG subtypes, mast cell degranulation, and release of mast cell–derived cytokines; the second involves T-lymphocyte activation via the T-cell receptor and costimulatory molecules, leading to release of T cell–derived cytokines, including IL-5, and the expansion and chemoattraction of eosinophils. Our present results are consistent with earlier findings that the first, antibody-driven, pathway is not required for the induction of BHR (23, 33) and provide evidence that CD40L, but not CD40, is essential for the induction of BHR via the second pathway.

In summary, we have found that both CD40 and CD40L are required for the production of IgE and that neither is necessary for development of pulmonary eosinophilia in response to allergen inhalation. CD40, but not CD40L, acts to enhance airway responsiveness in the absence of experimental antigenic stimulation. Induction of BHR after experimental antigen exposure requires CD40L, but not CD40. Thus, these two related molecules have differing roles in the development of the pathophysiologic features of asthma.

This work was supported by NIH grants HL36110, AI-42202, AI-31136, AI-31541, and AI-07512. One author (P.D.M.) is supported by the Foundation for Fellows in Asthma Research (through a grant from Forest Pharmaceuticals) and by the American Academy of Allergy, Asthma and Immunology President's Grant-in-Aid Award. One author (H.C.O.) is the recipient of an Asthma and Allergy Foundation of America Research Grant and is supported by the Pew Scholars Program in the Biomedical Sciences and the Asthma and Allergy Foundation of America.

1. Bentley A. M., Menz G., Storz C., Robinson D. S., Bradley B., Jeffery P. K., Durham S. R., Kay A. B.Identification of T lymphocytes, macrophages, and activated eosinophils in the bronchial mucosa in intrinsic asthma: relationship to symptoms and bronchial responsiveness. Am. Rev. Respir. Dis.1461992500506
2. Hogg J. C.Pathology of asthma. J. Allergy Clin. Immunol.92199314
3. Postma D. S., Bleecker E. R., Amelung P. J., Holroyd K. J., Xu J., Panhuysen C. I., Meyers D. A., Levitt R. C.Genetic susceptibility to asthma—bronchial hyperresponsiveness coinherited with a major gene for atopy. N. Engl. J. Med.3331995894900
4. Hanrahan J. P., Tager I. B., Segal M. R., Tosteson T. D., Castile R. G., Van Vunakis H., Weiss S. T., Speizer F. E.The effect of maternal smoking during pregnancy on early infant lung function. Am. Rev. Respir. Dis.145199211291135
5. Garssen J., Van Loveren H., Van Der Vliet H., Bot H., Nijkamp F. P.T cell-mediated induction of airway hyperresponsiveness and altered lung functions in mice are independent of increased vascular permeability and mononuclear cell infiltration. Am. Rev. Respir. Dis.1471993307313
6. Kaminuma O., Mori A., Ogawa K., Nakata A., Kikkawa H., Naito K., Suko M., Okudaira H.Successful transfer of late phase eosinophil infiltration in the lung by infusion of helper T cell clones. Am. J. Respir. Cell Mol. Biol.161997448454
7. Corry D. B., Folkesson H. G., Warnock M. L., Erle D. J., Matthay M. A., Wiener-Kronish J. P., Locksley R. M.Interleukin 4, but not interleukin 5 or eosinophils, is required in a murine model of acute airway hyperreactivity. J. Exp. Med.1831996109117
8. Brusselle G. G., Kips J. C., Tavernier J. H., van der Heyden J. G., Cuvelier C. A., Pauwels R. A., Bluethmann H.Attenuation of allergic airway inflammation in IL-4 deficient mice. Clin. Exp. Allergy2419947380
9. Nakajima H., Iwamoto I., Tomoe S., Matsumura R., Tomioka H., Takatsu K., Yoshida S.CD4+ T-lymphocytes and interleukin-5 mediate antigen-induced eosinophil infiltration into the mouse trachea. Am. Rev. Respir. Dis.1461992374377
10. MacLean J. A., Ownbey R., Luster A. D.T cell-dependent regulation of eotaxin in antigen-induced pulmonary eosinophilia. J. Exp. Med.184199614611469
11. Krinzman S. J., De Sanctis G. T., Cernadas M., Mark D., Wang Y., Listman J., Kobzik L., Donovan C., Nassr K., Katona I., Christiani D. C., Perkins D. L., Finn P. W.Inhibition of T cell costimulation abrogates airway hyperresponsiveness in a murine model. J. Clin. Invest.98199626932699
12. Lambert L. E., Berling J. S., Kudlacz E. M.Characterization of the antigen-presenting cell and T cell requirements for induction of pulmonary eosinophilia in a murine model of asthma. Clin. Immunol. Immunopathol.811996307311
13. Castigli E., Alt F. W., Davidson L., Bottaro A., Mizoguchi E., Bhan A. K., Geha R. S.CD40-deficient mice generated by recombination-activating gene-2-deficient blastocyst complementation. Proc. Natl. Acad. Sci. USA9119941213512139
14. Kawabe T., Naka T., Yoshida K., Tanaka T., Fujiwara H., Suematsu S., Yoshida N., Kishimoto T., Kikutani H.The immune responses in CD40-deficient mice: impaired immunoglobulin class switching and germinal center formation. Immunity11994167178
15. Xu J., Foy T. M., Laman J. D., Elliott E. A., Dunn J. J., Waldschmidt T. J., Elsemore J., Noelle R. J., Flavell R. A.Mice deficient for the CD40 ligand. Immunity11994423431
16. Wiley J. A., Harmsen A. G.CD40 ligand is required for resolution of Pneumocystis carinii pneumonia in mice. J. Immunol.155199535253529
17. Castigli E., Fuleihan R., Ramesh N., Tsitsikov E., Tsytsykova A., Geha R. S.CD40 ligand/CD40 deficiency. Int. Arch. Allergy Immunol.10719953739
18. Kiener P. A., Moran-Davis P., Rankin B. M., Wahl A. F., Aruffo A., Hollenbaugh D.Stimulation of CD40 with purified soluble gp39 induces proinflammatory responses in human monocytes. J. Immunol.155199549174925
19. Stout R. D., Suttles J., Xu J., Grewal I. S., Flavell R. A.Impaired T cell-mediated macrophage activation in CD40 ligand-deficient mice. J. Immunol.1561996811
20. Campbell K. A., Ovendale P. J., Kennedy M. K., Fanslow W. C., Reed S. G., Maliszewski C. R.CD40 ligand is required for protective cell-mediated immunity to Leishmania major. Immunity41996283289
21. Soong L., Xu J. C., Grewal I. S., Kima P., Sun J., Longley B. J., Ruddle N. H., McMahon-Pratt D., Flavell R. A.Disruption of CD40-CD40 ligand interactions results in an enhanced susceptibility to Leishmania amazonensis infection. Immunity41996263273
22. van Essen D., Kikutani H., Gray D.CD40 ligand-transduced co-stimulation of T cells in the development of helper function. Nature3781995620623
23. Mehlhop P. D., van de Rijn M., Goldberg A. B., Brewer J. P., Kurup V. P., Martin T. R., Oettgen H. C.Allergen-induced bronchial hyperreactivity and eosinophilic inflammation occur in the absence of IgE in a mouse model of asthma. Proc. Natl. Acad. Sci. USA94199713441349
24. Kurup V. P., Mauze S., Choi H., Seymour B. W., Coffman R. L.A murine model of allergic bronchopulmonary aspergillosis with elevated eosinophils and IgE. J. Immunol.148199237833788
25. van de Rijn M., Mehlhop P. D., Judkins A., Rothenberg M. E., Luster A. D., Oettgen H. C.A murine model of allergic rhinitis: studies on the role of IgE in pathogenesis and analysis of the eosinophil influx elicited by allergen and eotaxin. J. Allergy Clin. Immunol.10219986574
26. Daikh D. I., Finck B. K., Linsley P. S., Hollenbaugh D., Wofsy D.Long-term inhibition of murine lupus by brief simultaneous blockade of the B7/CD28 and CD40/GP39 costimulation pathways. J. Immunol.159199731043108
27. Durie F. H., Fava R. A., Foy T. M., Aruffo A., Ledbetter J. A., Noelle R. J.Prevention of collagen-induced arthritis with an antibody to gp39, the ligand for CD40. Science261199313281330
28. Gerritse K., Laman J. D., Noelle R. J., Aruffo A., Ledbetter J. A., Boersma W. J., Claassen E.CD40-CD40 ligand interactions in experimental allergic encephalomyelitis and multiple sclerosis. Proc. Natl. Acad. Sci. USA93199624992504
29. Adawi A., Zhang Y., Baggs R., Rubin P., Williams J., Finkelstein J., Phipps R. P.Blockade of CD40-CD40 ligand interactions protects against radiation-induced pulmonary inflammation and fibrosis. Clin. Immunol. Immunopathol.891998222230
30. Adawi A., Zhang Y., Baggs R., Finkelstein J., Phipps R. P.Disruption of the CD40-CD40 ligand system prevents an oxygen-induced respiratory distress syndrome. Am. J. Pathol.1521998651657
31. Lane P., Brocker T., Hubele S., Padovan E., Lanzavecchia A., McConnell F.Soluble CD40 ligand can replace the normal T cell-derived CD40 ligand signal to B cells in T cell-dependent activation. J. Exp. Med.177199312091213
32. Wiley J. A., Geha R., Harmsen A. G.Exogenous CD40 ligand induces a pulmonary inflammation response. J. Immunol.158199729322938
33. Hogan S. P., Mould A., Kikutani H., Ramsay A. J., Foster P. S.Aeroallergen-induced eosinophilic inflammation, lung damage, and airways hyperreactivity in mice can occur independently of IL-4 and allergen-specific immunoglobulins. J. Clin. Invest.99199713291339
34. Lei X., Ohkawara Y., Stampfli M. R., Mastruzzo C., Marr R. A., Snider D., Xing Z., Jordana M.Disruption of antigen-induced inflammatory responses in CD40 ligand knockout mice. J. Clin. Invest.101199813421353
35. Brewer J. P., Kisselgof A. B., Martin T. R.Genetic variability in pulmonary physiological, cellular, and antibody responses to antigen in mice. Am. J. Respir. Crit. Care Med.160199911501156
Address correspondence to: Thomas R. Martin, M.D., The Floating Hospital for Children, Dept. of Pediatrics, Pulmonary Div., 750 Washington St., #343, Boston, MA 02111. E-mail:

Abbreviations: Aspergillus fumigatus, Af; analysis of variance, ANOVA; bronchoalveolar lavage, BAL; BAL fluid, BALF; bronchial hyperresponsiveness, BHR; lacking CD40, CD40 −/−; lacking CD40 ligand, CD40L −/−; enzyme-linked immunosorbent assay, ELISA; eosinophil, EOS; pulmonary conductance, Gl; hematoxylin and eosin, H&E; immunoglobulin, Ig; interleukin, IL; knockout, KO; methacholine, MCh; normal saline, NS; ovalbumin, OVA; standard error of the mean, SEM; wild-type, WT.

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