Inhibition of protein kinase C in PHA-activated PBMC treated with anti-HLA class I monoclonal antibody is associated to decreased proliferation and expression of cell cycle related genes.

Treatment of PHA-activated PBMC with anti-HLA class I monoclonal antibody (mAb 01.65) shows: 1) depletion of particulate protein Kinase C (PKC) and partial reduction of cytosolic PKC after only 10 min.; 2) inhibition of tritiated thymidine (3H-Td) incorporation; 3) slowing down of cell cycle; 4) reduced expression of four cell cycle related genes. These findings suggest that the depletion of PKC is reflected on the cell cycle progression and expression of cell cycle related genes. We studied, in PHA-activated PBMC cultures, the effect of N-N-Staurosporine (StSp) acting as PKC inhibitor at nanomolar concentrations, alone and combined with mAb 01.65. StSp, inhibits the proliferative response of PHA stimulated PBMC in a competitive fashion with mAb 01.65. We report here that StSp alone and combined with mAb 01.65 affects also the expression of c-myc and cdc2 and the membrane expression of two proliferation markers: IL-2R (CD25) and TfR (CD71).