Investigation of the immune response to aerobic and anaerobic intestinal bacteria in a patient with Crohn's disease.

The immune response to aerobic and anaerobic intestinal bacteria in a patient with Crohn's disease with an intestinal fistula was investigated with various serological techniques. Two aerobic bacterial species, E. dispar and P. mirabilis, and four strict anaerobic bacterial species, B. fragilis ss. fragilis, F. varium and two different strains of C. perfringens, were isolated from fistula secretion of the patient. These strains were used as antigens for tube agglutination, passive hemagglutination, indirect immunofluorescence and immune hemolysis assays with serum specimens obtained before and after operation of the patient. Immune responses were demonstrated to the aerobic as well as to the anaerobic bacterial strains isolated from the patient's fistula. In connection with the operation an active immune response was demonstrated to the aerobic and anaerobic bacterial isolates. Antibodies belonging to IgG and IgA took part in the active immune response while IgM was very little involved. Antibodies responsible for passive hemagglutination reactions were resistant to treatment with beta-mercaptoethanol. Antibodies to aerobic and anaerobic Gram-negative rods were shown to have complement fixing activity. The importance of the demonstrated antibodies for the host's defence against normal intestinal microorganisms and the inflammatory reaction as a consequence of chronic antigenic stimulation in the diseased part of the intestine in patients with Crohn's disease is discussed.