Application-dependent immunomodulating and antimetastatic efficacy of thymic peptides in BALB/c-mice

The immunomodulating and antimetastatic activity of clinically approved, low molecular weight, standardized thymic peptide (TP) preparations was evaluated in BALB/c-mice. Daily applications (subcutaneously, s.c.; intraperitoneally, i.p.; intramusculary, i.m.) of two commercially available TP preparations (7 consecutive days, 10, 50 and 100 micrograms per mouse and injection) up-regulated the thymus weight and thymocyte counts as well as peripheral blood leukocyte and lymphocyte counts in liver metastases-bearing mice. The immunomodulating activity of TP application was most pronounced and statistically significant for thymus weight and counts of thymocytes, leukocytes and lymphocytes after s.c. administration of both TP preparations and concentrations. I.p. and i.m. TP-injections were less effective at reaching statistical significance, however, for defined dosages and parameters, only. To evaluate the influence of TP on experimental liver metastases, RAW 117 lymphosarcoma cells were intravenously inoculated into BALB/c-mice. TP (10, 50, 100 micrograms/mouse) were s.c., i.p. and i.m. administered daily for 7 consecutive days starting 24 hours after tumor cell challenge. Liver colonization was investigated on day 14 after tumor cell inoculation and demonstrated a statistically significant (p < 0.05) reduction of experimental liver metastases for s.c. (both preparations and concentrations) as well as i.p. and i.m. (dose-dependent) TP-treated mice.