LYMPHOKINE ACTIVITY IN THE CARP Cyprinus carpio

This thesis describes experiments which demonstrate that the teleost C. carpio, is capable of elaborating substances whose in vitro effects are analogous to those of mammalian lymphokines; and which also affect in vivo functions. In vitro stimulation of leucocytes from carp pronephros, both with antigens and mitogens, was used to provide culture supernatants which were applied to in vitro assay systems. These assay systems sought to determine the effects of the supernatants on other leucocytes. The experiments showed that the supernatants contained at least two types of mediator: a) a factor which inhibited the random movement of pronephros cells (possibly MIF or LIFI). b) a factor which enhanced the directional movement of pronephros cells (possibly CF). The CF-like activity could be detected in supernatants sooner and in lower concentrations than the MIF-like activity. Intraperitoneal injection of supernatants leads to an enhanced uptake of carbon into the lymphoid organs. The factors responsible for this could not be determined, however it is suggested that MIF may play a part. These studies showed considerable variability in results, hence the lymphoid organs of stock fish were examined for melano-macrophage centres (MMC). It was found that there was a great variation in the numbers of MMC in the spleens of fish of similar ages. The probable sources of the wide variation in normal fish are discussed. This is the first study to show the presence of CF-like mediators in the supernatants derived from stimulated fish leucocytes. The presence of lymphokines in fish supports the theory that lymphokine production is a fundamental property of vertebrate leucocytes and is of central importance in in vivo cell-mediated immunity