Antigens of Leptotrichia buccalis II. Their reaction with complement fixing IgM in human sera.

A soluble antigen preparation (SALB), a water soluble lipopolysaccharide preparation, and a phenol soluble lipopolysaccharide preparation of Leptotrichia buccalis were used in a variety of serologic tests with human sera from periodontal patients. Sera from five of six periodontal patients reacted in hemolysis and indirect passive hemagglutination tests using SALB or water soluble lipopolysaccharide treated sheep red blood cells (SRBC). Only one of six individuals showed a titer to the phenol soluble lipopolysaccharide preparation in the same tests. The sera and antigens that gave positive results in the hemolysis test did not react in standard complement fixation or immunodiffusion tests. Using an indirect passive hemagglutination test with SALB treated tanned sheep red blood cells, five of six sera were again positive, however the titers were two to three fold lower. Adsorption of the SALB with SRBC removed the antigen reactive in the untanned cell test but had no effect on the antigen in the tanned cell test. On the basis of different antigen absorption characteristics to SRBC, these results suggest humans produce antibody reactive with both protein and lipopolysaccharide antigens of L. buccalis.