Comparative Immunity

From DrugPedia: A Wikipedia for Drug discovery

The field of immunology is concerned mostly with how innate and adaptive mechanisms collaborate to protect vertebrates from infection.Although many cellular and molecular actors have important roles, antibodies and lymphocytes are considered to be the principal players. Yet despite their prominence in vertebrate immune systems, it would be a mistake to conclude that these extraordinary molecules and versatile cells are essential for immunity. In fact, a determined search for antibodies, T cells, and B cells in organisms of the nonvertebrate phyla has failed to find them. The interior spaces of organisms as diverse as fruit flies, cockroaches, and plants do not contain unchecked microbial populations nonpeptide organic molecules that have antibiotic activity. Among these agents are enzymes that digest microbial cell walls, peptides and a protein that damages microbial membranes, and the small organic molecules phytoalexins. The importance of the phytoalexins is shown by the fact that mutations that alter their biosynthetic pathways result in loss of resistance to many plant pathogens. In some cases, the response of plants to pathogens goes beyond this chemical assault to include an architectural response, in which the plant isolates cells in the infected area by strengthening the walls of surrounding cells.