Immunomodulation with P40, an insoluble delipidated fraction of Corynebacterium granulosum

Abstract

The immunological responses to sheep red blood cells (SRBC) were evaluted in mice in order to study the immunomodulating effects of an insoluble fraction of Corynebacterium granulosum, designated P40. A single intravenous (IV) injection of 50 μg or more of P40 was able to stimulate the reticulo-endothelial system, as measured by the spleen index. A single IV injection of 250 μg of P40, given seven days prior to IV sensitization of groups of mice with varying doses of SRBC, was able to amplify both humoral and cellular immune responses. Lower doses of P40 given subcutaneously (SC) were able to potentiate delayed-type hypersensitivity (DTH) to SRBC. Potentiation depends on the route, dose and time of the P40 injection in relation to the time and route of sensitization. A bimodal activity of P40 was observed: one peak was noted when SRBC were mixed with P40, and a second peak occurred when P40 was injected at the same site four to five days prior to immunization. Maximal potentiation was achieved when SRBC were introduced SC together with 5 μg of P40.