Comparison of the in vitro effects of thymopoietin pentapeptide and levamisole on peripheral E-rosette forming cells.

The effects of thymopoietin pentapeptide (TP5) and levamisole on human peripheral T lymphocytes were investigated by means of the E-rosette formation. Different kinds of E-rosette forming cells (RFC) were measured, i.e. active RFC (RFCa), total RFC (RFCt) and azathioprine-inhibited RFCt. The effects of TP5 and levamisole on RFC were very similar. Azathioprine inhibition of RFCt was restored completely by levamisole and partially by TP5. Both substances enhanced RFCa of healthy subjects and RFCt of patients in which these were low. TP5 and levamisole may act via a common cyclic nucleotide second signal.