Cellular responses to bacterial lipopolysaccharide: LPS facilitates priming of antigen-reactive T cells

Abstract

The effect of bacterial lipopolysaccharide (LPS) on the capacity of mice to mount a specific T-cell response to a protein antigen was examined. Inoculation of mice with LPS and ovalbumin (OA) resulted in enhancement of the T-cell proliferative response to OA. This enhancement was manifested in vitro by an increase in magnitude and by a more rapid appearance of the response after challenge with OA. This enhancement was also shown because the latent periods for the antigen-specific responses were reduced to 3 days after inoculation with antigen plus LPS, as compared with 5 days after inoculation with antigen alone. Various mouse strains, including the C3H/HeJ and C57BL/10ScN strains, responded to the adjuvant action of LPS at the T-cell level. Results suggest that LPS exerts this adjuvant effect by facilitating clonal expansion of antigen-reactive T cells during priming.