DIVERSITY OF IMMUNE-SYSTEMS

Explaining the diversity of immune reactions requires comparative immu nology that takes a phylogenetic view; there is interest in uncovering the underlying mechanisms throughout the animal kingdom. Because of t he complexities and diversities of individual phyla, comparative immun ology can compare and therefore reveal and elucidate immune mechanisms between and within major groups. There exist two categories of immune responses; 1) non-specific, innate, natural, non-adaptive, and non-an ticipatory; 2) induced, adaptive, specific, anticipatory responses. No n-specific mechanisms include the ubiquitous phagocytosis and encapsul ation. In invertebrates, several leukocyte types possess membrane asso ciated markers (e.g. beta(2)m, Thy-2, Lyt-, Lyt-2/3). Transplantation immunity, has revealed various degrees of specificity in sponges, coel enterates, annelids, insects, echinoderms and tunicates. Cytotoxicity is a crucial immunodefense function. Humoral immunity includes natural ly:occurring and inducible agglutinins, lysozymes, lysins, non-lysozym e bactericidins, and lysosomal enzymes. Humoral immunity in insects (e .g. cecropins and defensins) that lack specificity and memory, functio ns efficiently against microbial pathogens. Cytokine-like molecules, o f invertebrates, may regulate host defense responses by an acceptable network similar to that of vertebrates. Communication,and recognition molecules are universal since protozoans possess a pheromone (Er-1) th at is related to IL-2, IL-1 and TNF-like activities are found in annel ids, mollusks, echinoderms and tunicates. In the future molecular biol ogy must be used extensively to dissect immunodefense more fully, a mo re modern approach in understanding one component of an organism's tot ality.