Elevated mutant frequencies in gene lacI in splenic lipopolysaccharide blasts after exposure to activated phagocytes in vitro.
The interaction of B lymphocytes with phagocytes is critical for shaping the humoral immune response, as well as various aspects of normal and malignant B cell development, and has therefore been studied by immunologists in great detail. However, one potential outcome of this confrontation is often neglected, namely the mutagenicity of phagocytes to B lymphocytes. We are interested in phagocyte-induced B cell mutagenesis and have conducted a feasibility study on the utility of a transgenic reporter assay to evaluate mutant frequencies in B cells that have encountered phagocytes. An in vitro co-incubation system was designed in which splenic lipopolysaccharide (LPS) blasts carrying a phage lambda-derived lacI transgene were exposed to pristane-elicited peritoneal exudate cells (PEC). Mutant frequencies in LPS blasts were significantly increased (up to 6-fold) when the cells were co-incubated with PEC that had been stimulated by phorbol myristate acetate to undergo an oxidative burst. The lacI-based transgenic mutation assay proved also useful for assessing mutagenicity in vivo, as demonstrated by the detection of elevated mutant frequencies in the spleen (3-fold) and the inflammatory granuloma (4.7-fold) obtained from pristane-treated mice. We propose to utilize the lacI-based transgenic mutagenesis assay as a tool to evaluate mutational levels during normal and aberrant B cell differentiation.
Felix
K
K
Institut für Klinische Molekularbiologie and Tumorgenetik, GSF, München, Germany. felixk@dc37a.nci.nih.gov
Lin
S
S
Janz
S
S
D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics; D029968:Escherichia coli Proteins; D007763:Lac Operon; D056968:Lac Repressors; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016296:Mutagenesis; D009152:Mutagenicity Tests; D010529:Peritoneal Cavity / Q000166:cytology; D010586:Phagocytes / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics; D013154:Spleen / Q000166:cytology; D013729:Terpenes
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D056968:Lac Repressors; D012097:Repressor Proteins; D013729:Terpenes; C009042:pristane