Meeting Abstract

S6.1  Wednesday, Jan. 5  Environmentally induced stochasticity of adaptive immunity. Good, bad, or ugly? KLASING, K.C.; Univ. of California, Davis kcklasing@ucdavis.edu

Pathogens reproduce and evolve faster than their hosts by orders of magnitude, making the immune system’s job difficult. The innate immune system identifies pathogens using receptors that recognize evolutionarily conserved (predictable) molecular patterns, but the adaptive system rearranges its pathogen receptors (Ig and TCR) using somewhat random processes resulting in recognition of unpredictable molecular patterns (antigens). Further diversification is accomplished by vastly heterogeneous MHC-mediated antigen presentation. These diversity generating processes close the gap between the differential rates of evolution of hosts and pathogens. After accounting for antigen receptor and MHC diversification, an impressive amount of inter- and intra-individual noise in immune responses remains. Some of this variability is due to environmental factors like stress and diet. The immune system has nutrient receptors, including PPARs, RXRs, mTOR and VDR, that monitor the level of select nutrients and modulate immune responses. The ligands for these immunoregulatory receptors are often not nutritionally essential (carotenoids). The immunomodulatory effects of individual nutrients follow typical dose response relationships. However, the interactions between these immunoregulatory nutrients are strikingly unpredictable. It could be that this unpredictability adds real time stochasticity to the host’s response to its pathogens. Even within a social group of animals the specific food items selected, and thus the nutrient profiles, vary between individuals due to age, sex, social position, and individual tastes. Thus, diet diversifies the type of immune response that closely-related individuals use to defend against a novel pathogen. This real time variability might help thwart a pathogen that is successful in one host from encountering a similar immune response in other hosts.