Comparison of Bacteriolysis, Passive Hemolysis, and Bacterial Adherence Colony Formation for Detecting Antibdy-Forming Cells

Summary Three procedures were compared in a study to determine the cytokinetics of antibody formation to the lipopolysaccharide antigen of Escherichia coli 0127:B8. A bacterial cytoadherence colony procedure, recently described for enumerating antibody-forming cells to Salmonella flagellin, was adapted to enumerate antibody-forming cells to E. coli. Antibody plaque procedures, using either viable E. coli or lipopolysaccharide-sensitized red cells as indicator targets, were also used. The bacterial cytoadherence procedure was more sensitive than the complement dependent plaque methods. Mice immunized with 50 μg of E. coli antigen had approximately 50,000 to 60,000 plaque-forming cells and over 130,000 colony-forming cells at the peak of the immune response 5 days after immunization. The first antibody forming cells were detected 24–48 hr after immunization. Normal mice had lower numbers of “background” antibody-forming cells. After a lag of 3 days serum antibody titers correlated with the appearance of antibody-forming cells.