Legionella pneumophila-induced suppression of early blastogenic responsiveness of murine spleen cells to specific and nonspecific stimulation in vitro

Abstract

Legionella pneumophila whole cells, including viable organisms or a killed vaccine, early after injection into mice suppressed the blastogenic responses of mouse spleen cells to both specific (i.e.,Legionella) and nonspecific (i.e., plant mitogen andEschericia coli lipopolysaccharide) stimulators. Mice given injections of sublethal numbers of viableLegionella or of a killed vaccine evidenced 3–4 weeks thereafter a marked increase in blastogenic sensitivity of their spleen cells to theLegionella antigen, either whole cells or soluble antigen, but no increase in responsiveness to nonspecific mitogens (i.e., concanavalin A, phytohemagglutinin, andE. coli lipopolysaccharide) was evident. In contrast, during the first week or so after injection of mice with either viable or killedLegionella, marked suppression of blastogenic responsiveness of spleen cells toLegionella antigens was evident. Concomitant suppression also occurred to concanavalin A and phytohemagglutinin, as well as toE. coli lipopolysaccharide. However, by the second week after injection of the animals with live or killedLegionella, such suppression disappeared. The importance of such early specific suppression of a cellular immune response early after exposure toLegionella antigen, in contrast with the early and sustained rise in specific antibody formation is being further investigated.