Monoclonal antibody 4B4 blocks suppression of the immune response to Cryptomeria japonica pollen antigen

The monoclonal antibody 4B4 blocked the T8⁺ T cell-mediated suppression of IgE response to Cryptomeria japonica pollen antigen (CPAg). The helper T cells for IgE response to CPAg expressed 4B4 specificity, whereas the suppressor T cells did not. The 4B4 molecule on PBL was a heterodimer and three additional bands were detected on activated CPAg-specific T4⁺ T cells. They were not closely associated with HLA molecules. It is thus conceivable that the 4B4 molecule is not only a marker of helper T cells but also has an important role in the suppressor-helper interactions in the regulation of IgE response to CPAg.