Inhibition of lymphocyte proliferation by synthetic peptides homologous to human plasma apolipoproteins B and E.

Apolipoproteins B and E of the human plasma lipoproteins are known inhibitors of lymphocyte proliferation. In this report, two synthetic peptide amides, apoB3358-3372 and apoE141-155, showed a dose-dependent inhibition of both the murine mixed lymphocyte culture reaction and the anti-T3 induced proliferation of lymphocytes. Their structures and antiproliferative potencies were similar to that of the heptadecapeptide CKS-17, a consensus peptide of a highly conserved region among HTLV-I, -II and C-type human retroviral proteins. SP-9-2-amide, a peptide homologous to the amino-terminal half of CKS-17, also suppressed lymphocyte activation. In contrast, a peptide homologous to the gp41 protein of HTLV-III that is sequence related to CKS-17 (approximately 35% homology) showed little antiproliferative activity. Neurotensin, a control peptide, showed no activity. The results suggest that a basic tetrapeptide sequence common to CKS-17-amide, SP-9-2, apoB3358-3372 and apoE141-155, but not HTLV-III-amide may account, in part, for the antiproliferative activities of these peptides.