Enhancement of host defence by Y-19995 (2,4'-bis(1-methyl-2-dimethyl-aminoethoxyl)-3-benzoylpyridine dimaleate), a novel synthetic compound. I. Accelerated restoration from the leukocytopenia and augmented protection against microbial infections in immunocompromised mice.

Effects of a novel synthetic compound, Y-19995, on the host defence in immunocompromised mice were investigated in terms of the restoration of leukocytopenia and the protection against several microbial infections. Oral or intravenous administration of Y-19995 into mice after X-irradiation, treatment with cyclophosphamide or mitomycin C prevented the leukocytopenia to some extent and promoted the restoration in cell numbers of both the peripheral blood leukocytes and bone marrow. Intravenous administration of Y-19995 increased significantly the survival rates of X-ray irradiated mice against acute systemic infections with Escherichia coli, Pseudomonas aeruginosa and Candida albicans, and intramuscular infection with Escherichia coli. The clearance of Escherichia coli from the blood of X-ray irradiated mice was also promoted by the treatment with Y-19995. The augmented protection against microbial infections in immunocompromised hosts by Y-19995 may be attributed mainly to the prevention of leukocytopenia or the enhanced restoration from leukocytopenia.