B1 B-cells produce circulating natural antibodies (Abs) that provide ?innate-like? protection against bacterial and viral pathogens. These cells give raise adaptive responses to blood and air-borne pathogens, but apparently they are not involved in the control of protozoan parasite replication. B1 B-cells not only produce Abs but also they act as antigen presenting-cells and as regulator of other cell populations through cytokines production.
We observed that B1 B-cell from peritoneal cavity, differentiate into Ab-secreting plasma cell after CD40 (simulating T-cell interaction), LPS and CpG stimulation, but not with F(ab)2anti-u.(simulating BCR stimulation). These Ab-secreting plasma cells release high levels of IgM after TLR-9 and 4 ligation and only secrete IgG after CD40 stimulation. In order to determine an association between the cytokine profile and the isotype immunoglobulin, B1 B-cells obtained from peritoneal cavity of Balb/c mice were cultured during 24h with anti-CD40 (5ug/ml), LPS (5ug/ml), CpG (1ug/ml) or F(ab)2anti-u (10 ug/ml). After that IL-4, IL-6, IL-10, IL-5 and INF-gamma were determined in culture supernatant by ELISA. We observed that B1 B-cells did not produce IL-4, IL-5 and INF-gamma but they release IL-6 and IL-10 only after TLRs ligation. High levels of IL-6 were determined in supernatant of CpG stimulated B1 B-cells whereas high levels of IL-10 were present in supernatants of CpG and LPS stimulated B1 B-cells.
Our results show an association between IgM and IL-6 and IL-10 production during B1 B-cells differentiation but we can not find a link between IgG and the cytokines profile.
