Biotechnological production and functional characterization of leukocytic cytokine(s) with cytotoxic effect on resting but not activated thymocytes.
In the present report we describe the analysis of suppressive and cytotoxic factor(s) derived from Con A-induced porcine leukocyte culture supernatant solution(s) (PCAS). The supernatant solution(s) had been produced on a biotechnological scale using porcine peripheral blood leukocytes isolated from 200 to 1000 1 of porcine blood. The supernatant solution(s) were tested for their effect during murine T cell activation. We found that crude supernatant solution(s) contain suppressive and cytotoxic factor(s) (SF) which have a similar selectivity for non-activated thymocytes as suppressive factor(s) previously detected in the supernatant solution(s) of allo-antigen-stimulated murine spleen cell cultures. SF was obtained from crude serum-free culture supernatants by fractionated ammonium-sulphate precipitation between 35 and 45% saturation. SF has the following characteristics: its release into the culture supernatant is dependent on mitogenic stimulation, it acts during early stages of T lymphocytic activation, the activity towards naive thymocytes is most likely caused by an irreversible cytolytic mechanism, and phenotypically and functionally immature thymocytes are preferentially affected through exposure to SF.