Altered proliferative kinetics in PHA-activated human T-lymphocytes treated with the anti-HLA class I monoclonal antibody 01.65.

Anti-HLA class I monoclonal antibody (mAb) 01.65 inhibited phytohaemagglutinin (PHA)-induced human lymphocyte proliferation. The inhibitory effect was inversely correlated to the strength of the proliferative response. It was increased when lymphocytes were stimulated with suboptimal doses of PHA but it disappeared with supraoptimal doses. Proliferation inhibition was achieved by prolonging the cell cycle time and by slowing down its recruitment rate. The former effect was not restricted to the G1-phase but also included the S phase. These results support the idea that HLA class I molecules are important in the PHA-induced proliferation of human T-lymphocytes.