The purpose of the present study was to explore the effects of protein kinase C (PKC) stimulation on two cell surface receptors that regulate T cell growth: the T cell antigen receptor/CD3 complex and the CD2 antigen. The data show that PKC differentially regulates the expression and functions of CD2 and CD3 molecules. Thus, activation of PKC induced a decrease in cell surface levels of CD3 molecules but an increase in the expression of CD2 antigens. Additionally, prolonged stimulation of PKC inhibited subsequent T cell activation via CD3 but promoted activation via CD2 molecules. These results suggest that the CD2 cellular activation pathway would be preferred in T cells which have been exposed to stimulators of PKC. The molecular basis for the regulatory effects of PKC on CD3 and CD2 molecules and its physiological significance are discussed.