The effects of bacterial lipopolysaccharide, anti‐receptor antibodies and recombinant interferon on mouse B cell cycle progression using 5‐bromo‐2'‐deoxyuridine/hoechst 33258 dye flow cytometry

Abstract

Polyclonal stimulation of resting B cells with anti‐antigen receptor antibodies [anti‐IgM μ chain antibody (anti‐μ)] or with bacterial lipopolysaccharide (LPS) stimulates a proportion of B cells to proliferate. Exposure of resting B cells to both LPS and anti‐μ activates a larger population of resting B cells than either alone, suggesting a synergistic effect of these two stimuli. Although recombinant interferon (rIFN) either alone or in combination with anti‐μ has no apparent proliferative activity (as measured by [³H]thymidine incorporation), application of 5‐bromo‐2'‐deoxyuridine/Hoechst 33258 dye flow cytometry reveals a distinct effect of rIFN on B cell growth. In the presence of anti‐μ plus LPS, rIFN causes the majority of B cells to enter the cell cycle (CC), but a subset of B cells remains in the resting stage. Another subset of B cells has extremely rapid CC transit times, with a CC duration of less than 10 h. These studies show that both anti‐μ and LPS are competence factors (which move cells from the G₀ phase to the G₁ phase). LPS acts also as a CC progression factor, while rIFN is a CC potentiating factor.