Development and treatment of steroid resistant asthma model by adoptive transfer of murine helper t cell clones

Background

To investigate the role of helper T (Th) cells in steroid resistant (SR) asthma, steroid sensitive (SS) and resistant (SR) Th clones were selected in vitro, and then adoptively transferred into unprimed mice. Effect of CTLA4-Ig was analyzed both in vitro and in vivo.

Methods

For in vitro evaluation of steroid sensitivity, ovalbumin (OVA) reactive Th clones were cultured with antigen presenting cells and OVA in the presence of various concentrations of dexamethasone (DEX). Proliferative responses of Th clones were measured by ³H-thymidine incorporation. For in vivo evaluation, unprimed BALB/c mice were transferred with Th clones, challenged with OVA, and administered with DEX subcutaneously. Bronchoalveolar lavage fluid (BALF) was obtained 48 hr after challenge, and the number of infiltrating cells was differentially counted. CTLA4-Ig was administered either intravenously or intranasally.

Results

SS and SR clones were selected based on the suppressive effect of DEX on the proliferative responses of antigen-stimulated Th clones. Airway infiltration of eosinophils and lymphocytes of mice transferred with SS clones were effectively inhibited by the administration of DEX. In contrast, those of mice transferred with SR clones were not significantly inhibited. Administration of CTLA4-Ig significantly suppressed the proliferation of DEX-treated SR clones in vitro, and the eosinophil infiltration of mice transferred with SR clones in vivo.

Conclusions

Steroid sensitivity of Th clones assessed in vitro was consistent with that of adoptively transferred asthma model assessed in vivo. Costimulatory signal mediated through CD28 is crucial for the induction of steroid resistance both in vitro and in vivo.