The immune response in catfish, Mystus gulio

Light microscopic studies of the immune response of Mystus gulio were carried out. Antigen binding cells have been detected by plaque-forming cell (PFC) assay test in the spleen, head-kidney (HK) and thymus. Among these three organs, the HK is more pronounced in its response, and it is compared, on the basis of its histology of higher vertebrates. The peak response after primary and secondary immunizations was on day 7, in both circulating blood and the immune organs. The results suggest that HK in these fish might be the major organ for antibody secreting cells. The HA (haemoagglutinin) response was also for longer duration but only slightly more intense. The PFC response after the secondary immunization was for much longer duration and much more intense than after the primary immunization.