Difluoromethylornithine (DFMO) arrests murine CTL development in the late, pre-effector stage.
DL-alpha-Difluoromethylornithine (DFMO) is a specific inhibitor of the rate-limiting enzyme in polyamine biosynthesis, ornithine decarboxylase (ODC). DFMO (1 mM) added to C57BL/6 anti-DBA/2 murine mixed lymphocyte cultures (MLC) inhibited cytolytic T lymphocyte (CTL) activity on days 3 and 5 by 88% and 96%. Putrescine (PUT; 1 mM) and spermidine (SPD; 0.01 mM) reversed DFMO inhibition, indicating that DFMO inhibition was caused by ODC antagonism. T helper (Th) cell and accessory cell functions were not affected since DFMO did not inhibit MLC proliferation or lymphokine production. Furthermore, exogenous IL-1, IL-2, IL-4, interferon-gamma, or a rat Con A supernatant failed to abrogate DFMO inhibition. Inhibition was reversible within 48 h of removing cells from DFMO; moreover, subsequent development of DFMO-blocked CTL did not require CD4+ cells. Clonal expansion of CTL treated with 1 mM DFMO for three days in MLC, determined by subsequent analysis in limiting dilution microcultures, was only approx. 1 cell division less than control. These results indicate DFMO inhibition is exerted directly on the CTL, and that the process of differentiation was more affected by a reduction in polyamine biosynthesis than proliferation. This may be a useful model to the study stages and events of CTL development, and the roles played by polyamines in supporting these processes.
Schall
R P
RP
Department of Medical Microbiology and Immunology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Sekar
J
J
Tandon
P M
PM
Susskind
B M
BM
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D000518:Eflornithine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000096:biosynthesis; D007377:Interleukin-3 / Q000096:biosynthesis; D007700:Kinetics; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008815:Mice, Inbred Strains; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines / Q000378:metabolism; D011700:Putrescine / Q000494:pharmacology; D013095:Spermidine / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D007376:Interleukin-2; D007377:Interleukin-3; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D013095:Spermidine; D011700:Putrescine; D000518:Eflornithine