Background: We investigated the immunoreguratory role of the major histocompatibility complex in peripheral blood lymphocytes' proliferative response to mite antigen.
Method: Peripheral blood lymphocytes of Japanese asthmatic patients were incubated with antigen obtained from Dermatophagoides pteronyssinus with a molecular weight of about 15,000, with and without 0.05 microgram/mL of monoclonal antibody against HLA class I or class II for seven days at 37 degrees C humidified in 5% CO2 and 95% air.
Results: High and low responders to the mite body antigen were found among the patients while there were no high responders among the healthy individuals tested. In the mite-sensitive asthmatic patients, CD4+ T cells were the population that responded to the antigen. Depletion of CD8+ T cells from the peripheral blood lymphocytes of mite-insensitive individuals caused high responsiveness to the antigen, indicative that the mite-specific CD4+ T cells controlled the high responsiveness and the antigen-specific CD8+ T cells, the low responsiveness. Anti-HLA-DR monoclonal antibody inhibited responsiveness. In contrast, anti-HLA-DQ monoclonal antibody produced high responsiveness in low responders to mite antigen.
Conclusion: High T cell proliferative responsiveness to mite antigen was restricted by HLA-DR antigen through CD4+ T cells in high responders, whereas HLA-DQ antigen is a restriction antigen of low responsiveness through CD8+ T cells in low responders and non-atopic individuals.