In the serum of healthy and sick persons antibodies to Bucreroidaceae and Veillonella have been detected. The antibody titres to these anaerobic bacteria are commonly low, in adults, however, higher than in children. High antibody titres could be found in patients suffering from Crohn's disease and in cancer patients. Immune responses to anaerobic bacteria occur in periodontal processes, too. These antibodies belong mainly to the IgM class of immunoglobulines. On the contrary, antibodies observed in patients with sepsis belong to the IgG class.
The present communication intends to summarize current information concerning the presence of antibodies in the normal and diseased human host and possible cell-mediated immune reactions to members of the Bacteroidaceae and Veillonella. Virtually nothing is known about immune reactions to other anaerobic GRAM-negative bacteria normally present on the mucous membranes of man, i.e. Acidaminococcus, Selenomonas, vibrios and spirochetes. More extensive reviews have been presented earlier [20, 211.
Antibodies in normal human serum reacting with Gram-negative anaerobic bacteria
From time to time the microorganisms of the mucous membranes, or their products. may gain access to the tissues. Here they come into contact with phagocytes, which make the antigens available for antibody-producing cells. Therefore, antibodies reacting with components of the normal microflora occur frequently in man. Antibodies with specificities to Bacteroides and Fusobacterium species, Leptotrichia buccalis and Veillonella have thus been detected in normal human serum (Table I). The normally occurring antibodies are commonly present in small amounts, making the use of sensitive serological methods necessary to detect them. They are mostly directed against bacterial polysaccharides, v i ~. the 0-antigenic lipopolysaccharides, and belong to the IgM class of immunoglobulins. This is, however, not absolute. IgG antibodies with specificity to one or more surface anti-46 Nohrung. Bd 28, H .