The immune responses to soluble and cellular antigens in the teleost, Tilapia mossambica to soluble and cellular antigens

Abstract

The immune response of Tilapia mossambica to bovine serum albumin (BSA) and sheep red blood cells (SRBC) was characterized in detail in terms of the appearance of hemolysin plaque-forming cells and circulating antibodies at 30°C. Plaque-forming cells (PFC) were detected in the spleen, head-kidney and thymus of immunized fish and the maximum number was observed in these organs on the fifth day after immunization with SRBC. Peak circulating antibody response occurred on day 8 for SRBC and on day 11 for BSA. Following the second injection of the same antigen, a specific anamnestic response was observed with increased production of PFC and serum antibody. No cross reactivity was found when anti-SRBC antibody was tested with rat erythrocytes. Tests with 2-mercaptoethanol showed that all of the agglutinating antibody produced after both the first and second injection was mercaptoethanol sensitive. Analysis of histological and smear preparations revealed that there were consistent cellular changes occurring in the spleen as well as the head-kidney due to immunization.