MHC class II restriction for T cell proliferative response to mite antigen

We investigated the immunoreguratory role of the major histocompatibility complex in peripheral blood lymphocytes' proliferative response to mite antigen.

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.

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.

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.