Adjuvant activity of Propionibacterium acnes isolated from the human oral cavity

Abstract

The immunopotentiating activity of six strains of Propionibacterium acnes isolated from the human gingival crevice was studied. Cells of oral P. acnes increased the number of direct splenic plaque-forming cells (PFC) in mice immunized with 10 8 sheep red blood cells (SRBC), and enhanced the haemolytic antibody titres of sera in mice immunized with 10 9 SRBC. Cell walls, cell-wall mucopeptides and lipid-free cells showed marked adjuvant activity at levels similar to that observed with whole cells. The same route of administration of oral P. acnes with SRBC greatly enhanced the immune response. When P. acnes was administered 8 to 15 days before immunization with 10 8 SRBC, the PFC response increased. However, the PFC response was decreased when the P. acnes cells were given approximately 4 days before SRBC immunization. The diphasic activity of the microorganisms was observed with lower immunizing doses of antigen (10 6 SRBC). Both cells and cell walls of oral P. acnes showed slight adjuvant activity in the development of delayed-type hypersensitivity to bovine serum albumin in guinea pigs. Pretreatment with cells and cell walls 4 days or 8 days before the BSA immunization, however, produced no adjuvant effect.