Atrimustine

Immunosuppressants cyclosporin A (CsA), FK506, and KM2210 modulated colony formations of murine hematopoietic progenitor cells. In a 4-h treatment with CsA, 10 micrograms/ml increased the formation of colony-forming units of mixed lineages (CFU-Mix) but decreased the formation of highly proliferative potential colony-forming units (CFU-HPP); 1 microgram/ml of CsA increased the formations of CFU-HPP, CFU-Mix, and colony-forming units of granulocytes/macrophages (CFU-GM); 0.1 microgram of CsA increased the formation of CFU-Mix and burst-forming units of erythroid lineage (BFU-E). Lower doses of CsA appeared to induce an increase in various colony formations. FK506 increased CFU-HPP and CFU-Mix formations at lower doses. Another immunosuppressant, KM2210, increased CFU-HPP and CFU-GM formations but decreased CFU-Mix and BFU-E formations. In a 24-h treatment, 10 micrograms/ml and 1 microgram/ml of CsA inhibited all the colony formations, but 0.1 microgram/ml of CsA increased CFU-Mix, CFU-GM, and BFU-E formations. Similarly, 100 ng/ml and 10 ng/ml of FK506 decreased all the colony formations but 1 ng/ml of FK506 increased CFU-HPP and CFU-GM formations. KM2210 inhibited all the colony formations. These findings showed that lower doses of CsA and FK506 appeared to increase the colony formations, although higher doses of these drugs decreased the colony formations, similar to the findings in a 4-h treatment. On the other hand, KM2210 showed opposing effects on colony formation with 4-h and 24-h treatments.

Cyclosporin A (CsA) inhibited interleukin 2 (IL-2), IL-3, interferon gamma (IFN gamma), GM-CSF and tumor necrosis factor alpha (TNF alpha) mRNA expression in spleen cells stimulated with concavalin A (Con A) when determined by the semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) method. FK506 which has a similar immunosuppressive mechanism to that of CsA also showed the same inhibitory effects except for decreased IL-5 and IL-6 mRNA expression. In contrast, both CsA and FK506 enhanced transforming growth factor beta (TGF beta) and IL-1 beta mRNA expression. Another immunosuppressant KM2210 did not show any inhibitory effects on cytokine gene expression but rather enhanced IL-10, IL-6, TGF beta and IL-1 mRNA expression, thus suggesting that KM2210 has a completely different immunosuppressive mechanism from that of CsA and FK506. Anti-TFG beta 1 antibody abrogated the suppression by KM2210 of BALB/c anti-3H/He mixed lymphocyte reaction (MLR) whereas this antibody did not abrogate the suppression by CsA and FK506 of BALB/c anti-C3H/He MLR. These results indicate that TGF beta is one of the major cytokines in KM2210 immunosuppression, in addition to IL-10, but not in immunosuppression by CsA and FK506.