Ovocystatin tetramer – effect on humoral immune response in SRBC-immunized mice and cytotoxic activity.

The effect of chicken egg white cystatin, similar to human cystatin C, was investigated in SRBC (sheep red blood cells)-immunized mice. Monomeric cystatin of chicken egg white was isolated and polymerized to tetramer form. Animals received ovocystatin tetramet (OT) 4 times at doses of 2, 0.2 and 0.02 mg/kg, intraperitoneally. SRBC immunization was performed 24 hours after the last dose, or 2 hours before the first dose of the tested compound. The number of antibody forming cells (AFC), total and 2-mercaptoethanol resistant serum agglutination titers were determined. OT has a varied effect on the humoral response of SRBC immunized mice. The most interesting effects were found when the OT was administered upon antigen. The inhibitory effect on AFC and total antibody titre was observed on day 4, and stimulation on total antibody titre and IgG titre on day 7 following OT administration with antigen. Additionally, OT showed no cytotoxic activity in relation to normal and cancer cell lines.