[Studies on an extract from Haemophilus influenzae type a. I.--Antigenic and immunogenic studies (author's transl)]

Haemophilus influenzae is the bacteria most commonly found in chronical bronchitis not treated by antibiotic therapy. Experimental studies have suggested that the destruction of the ciliated respiratory epithelium is in conjunction with the toxic product of the cell-wall of this bacteria. Endotoxin is extracted by phenol-water procedure. Toxicity is reduced by mild hydrolysis. Antigenicity of the preparation is controlled by gel diffusion in a parallel sides-tank diffusion and electroimmunodiffusion. These methods show that common antigenicity is not affected by hydrolysis. After immunisation by that preparation, circulating antibodies are detected by passive hemagglutination and immuno-precipitation. The immunized rabbits have agglutinin titer of 1 : 256th. Antigenicity of this bacterial extract is preserved and the preparation is still immunogenic.