Mouse B1 cell line responds to lipopolysaccharide via membrane-bound CD14

The role of membrane-bound CD14 in the response of mouse B1 cell lines to l ipopolysaccharide (LPS) was studied. The surface profile of mouse TH2.52 B cells was positive for CD5, IgM, B220, CD11b and F4/80, suggesting that TH2 .52 cells carried the typical phenotype of B1 cells. Furthermore, TH2.52 B1 cells were found to express membrane-bound CD14, which plays a critical ro le in LPS recognition. TH2.52 B1 cells responded to a very low concentratio n of LPS and exhibited: (i) augmentation of DNA synthesis; (ii) activation of nuclear factor (NF)-kappaB; and (iii) phosphorylation of extracellular s ignal regulated kinase 1/2 (Erk1/2). They were markedly inhibited by anti-C D14, antibody. Therefore, the expression of membrane-bound CD14 was suggest ed to provide high sensitivity to LPS for TH2.52 BI cells.