RESUMO
We have previously reported that a CD_(20) monoclonal antibody (HI_(47)) had obvious inhibition to ~3H-TdR incorporation of tonsil B cells in SAC drived system. This paper describes that McAb HI_(47) also markedly inhibited ~3H-UdR uptake and enlargement of B lymphocytes induced by SAC. However, it had no effect on B cell activation in PMA and anti-immunoglobul in antibody drived systems and the proliferation of established T, B and myeloid cell lines. The non-specific inhibition of HI_(47) Fc fragment had been ruled out by the experiments with irrelative MoAbs, which Ig subclass was same as HI_(47) (IgG_3),and with HI_(47) F (ab')2 fragment. Exposure of tonsil B cell to either SAC or PMA resulted in an increase in expression of HI_(47) antigen. McAb HI_(47), neverthless, induced reduction of HI_(47) antigen expressed on B cells stimulated by SAC. but not by PMA. In conclusion, antigen HI_(47) (CD_(20)) only involved in the SAC-activation pathway. The modulation of HI47 antigen by McAb HI47 may be one of the mechanisms of the depressed SAC activation.