Phylogeny of immune recognition: role of alloantigens in antigen presentation in channel catfish immune responses.

Previous work from this laboratory demonstrated the importance of antigen processing and presentation in the generation of secondary in vitro immune responses of channel catfish to both simple and complex T-dependence antigens. Further, the usage of functionally active long-term monocyte lines as antigen-presenting cells (APCs) revealed 'putative restriction' of immune responses by peripheral blood leucocytes (PBL) as responders. In addition, these long-term cell lines proved to be effective antigens for the production of specific alloantisera. Studies were therefore conducted to determine the importance of these alloantigens in the immunological recognition of foreign T-dependent antigens in the channel catfish. The addition of homologous, but not heterologous, alloantisera to cultures of antigen-pulsed cell line APCs and autologous immune PBL responders resulted in quantitative decreases in the antigen-specific proliferative responses. Taken together, these results provide evidence that alloantigens [presumably major histocompatibility complex (MHC) or MHC-like molecules] govern antigen presentation and putative restriction of teleost immune responses similar to the situation in mammals.