Opposing effects of protein tyrosine kinase inhibitors on the monoclonal antibody induced internalization of CD3 and CD4 antigens

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Abstract
We have previously demonstrated that the monoclonal antibody (mAb)‐induced moduiation of CD3 and CD4 antigens from the surface of human peripheral blood lymphocytes is not dependent from protein kinase C activity (Thuillier et al., Eur. J. Immunol. 1990. 20: 1197). In the present report we study the effect of genistein and of herbimycin A, two potent inhibitors of protein tyrosine kinases (PTK), on the mAb‐induced modulation of CD3 and CD4 surface antigens. Both genistein and herbimycin inhibited the mAb‐induced internalization of CD3 and, in contrast, facilitated that of CD4 antigen. These results indicate that the mAb‐induced modulation of CD3 is essentially dependent on the PTK pathway, whereas PTK appear to negatively regulate the mAb‐induced modulation of CD4.