In vitro effects of the antiallergy compound,CI-949, on interleukin-1 and 2 release,and on mitogen and alloantigen responsiveness

CI-949 (5-methoxy-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H-indole-2-carboxamide,l-arginine salt), an antiallergy compound was found to be a weak inhibitor of IL-1 release from LPS-stimulated murine peritoneal exudate cells and human peripheral blood leukocytes, with IC₅₀s of 186.2 and 267.9 M, respectively. CI-949 was also a poor inhibitor of release of IL-2 from Con A-stimulated rat spelenocytes (37% inhibition at 100 M). CI-949 did produce concentration-related inhibition of the response of human lymphocytes to PHA and Con A (IC₅₀s=44.7 and 21.5 M, respectively) as well as in the mixed lymphocyte reaction (MLR) (IC₅₀=16.8 M). The clinical significance of these latter findings is unknown at present.