Adjuvant action of bacterial lipopolysaccharide in induction of delayed-type hypersensitivity to protein antigens. II. Relationships of intensity of the action to that of other immunological activities.

Various kinds of lipopolysaccharides (LPS) isolated from different bacterial strains exhibited more or less an adjuvant action in induction of delayed-type footpad response to ovalbumin (OA) in mice when antigen was injected subcutaneously together with LPS. There was a wide diversity in strength of the adjuvant action of LPS, and the action of the 03 antigen isolated from the culture supernatant fluid of Klebsiella was the most potent of eleven kinds of LPS tested. Besides this substance, LPS extracted from Escherichia coli 08, 09 and 0128, and Salmonella typhosa exhibited relatively strong action. The difference in strength of the action of the high and low active LPS in induction of delayed-type hypersensitivity could be observed at any doses of OA and LPS. The strength of the adjuvant activity of LPS in induction of delayed-type hypersensitivity roughly correlated with that of their adjuvant activity in augmenting immunological memory for the secondary antibody response to OA and also their ability to enlarge the regional lymph node, whereas it did not apparently correlate with that of their activity to stimulate B cells polyclonally and their ability to enlarge the spleen.