Inhibition by oxisuran of cell-mediated hypersensitivity by decrease in numbers of specifically sensitized cells.

Oxisuran, 2-([methylsulfinyl]acetyl)pyridine, has previously been shown to selectively suppress cell-mediated immunity, as measured by prolongation of allograft survival, without inhibition of humoral immunity. In the present investigation, the influence of this compound on lymphoid cell transfer of delayed hypersensitivity was studied. In actively sensitized animals, including endotoxin-sensitized mice and rabbits, ovalbumin-, dinitrochlorobenzene-, and dinitrofluorobenzene-sensitive guinea pigs, or tuberculin-sensitive rats, daily treatment during the interval just preceding the elicitation and expression of the hypersensitivity was most inhibitory. In both endotoxin-sensitive mice and ovalbumin-sensitive guinea pigs, treatment of the sensitized cell donor just prior to lymphoid cell harvest and transfer resulted in inhibition of the expression of the hypersensitivity in untreated recipients. Approximately 10(4) fewer specifically sensitized lymphoid cells, but not fewer viable cells, were present in passively transferred cell preparations. In contrast, treatment of the lymphoid cell recipient in the same experimental model did not influence the expression of the transferred hypersensitivity. The results suggest that oxisuran may influence an as yet undefined event prior to the expression of a cell-mediated hypersensitivity response in sensitized animals.