The Influence of Endotoxin on Resistance to Infection.

NDOTOXINS of Gram-negative bacteria can either raise or lower resistance to infection. This variable effect can be partly explained by the dual nature of endotoxin, a substance that is both antigenic and toxic. Toxicity takes the form of abrupt disturbances in leukocytes, body temperature, circulatory dynamics, intestinal motility, carbohydrate metabolism, serum proteins, and endocrine secretion. During the course of these profound abnormalities, it is not surprising that resistance to infection may fall sharply. The antigenic activity of endotoxins, on the other hand, may elevate resistance to infection by stimulating specific immunity to the homologous bacteria. The Gram-negative endotoxins have been designated "O" antigens and their specific immunologic properties provide the only means of distinguishing between endotoxins of different bacterial species. In contrast to these antigenic differences, there is striking uniformity in toxic manifestations of endotoxins from all Gram-negative bacteria. analysis