Polyclonal Activation of CR+ and CR- B Lymphocytes: The Kinetics of Initiation of DNA and Immunoglobulin Synthesis by Lipopolysaccharide

Abstract

B cells that carry the complement receptor (CR⁺) were separated from B cells that lack the complement receptor (CR^-) by velocity sedimentation or by passage through C-coated Sephadex columns. The kinetics of responses to bacterial lipopolysaccharide (LPS) in both B cell subpopulations were determined in three assay procedures: 1) incorporation of radioactive thymidine into DNA; 2) incorporation of radioactive leucine into immunoglobulin; 3) enumeration of cells forming polyclonal antibody to the 2,4,6-trinitrophenyl hapten. Although both subpopulations of B cells responded to LPS, they differed in the time course. CR^- B cells responded with a delay of approximately 24 hr as compared with the response of CR⁺ B cells. The implications to the ontogenetic status of CR⁺ and CR^- B subpopulations are discussed.