Ten new analogues of thymopentin (TP-5) were synthesized. Their biolog
ical activities were evaluated in the recovery assay of T-lymphocytes,
the active E-rosettes test and modulation of mitogen response of T-ce
lls. In vitro, these cyclic dipeptides had a predominantly inhibitory
effect in all tests, only c(Ser-Acp) stimulated the response of T-lymp
hocytes to low concentrations of Con A and increased the number of act
ive E-rosettes.