Antibody-producing cell responses to an isolated outer membrane protein and to complexes of this antigen with lipopolysaccharide or with vesicles of phospholipids from Proteus mirabilis.

Antibody-producing cell responses of mice to a protein isolated from the outer membrane of Proteus mirabilis were typical of the responses to a thymus-dependent antigen. The immunoglobulin G antibody-producing cell responses to the protein were increased after administration of the antigen complexed with either lipopolysaccharide or with vesicles of phospholipids extracted from P. mirabilis. The protein in turn significantly increased the immune response to lipopolysaccharide and also converted this response from predominantly immunoglobulin M to predominantly immunoglobulin G.