Bancroftian filariasis: circulating B-1 cells decreased in microfilaria carriers and correlate with immunoglobulin M levels.

B-1 cells play an important role in the outcome of infection in schistosomiasis, pneumonia and experimental filariasis. However, no information exists regarding status of B-1 cells in clinical manifestations of human filariasis. We investigated the levels of B-1 cells from the total B cells by flow cytometry. Significantly low levels of B-1 cells and IgM antibodies were detected against a wide variety of autoantigens in microfilariae carriers as compared to endemic controls and patients with chronic pathology. A positive correlation was found between IgM antibodies to actin and ss-DNA. Absorption of plasma with soluble actin, myosin and lipopolysaccharides (LPS) resulted in significant removal of antifilarial antibodies. Affinity-purified anti-ss-DNA antibodies were found to be reactive to filarial antigens and various autoantigens. Further, a positive correlation was found between polyreactive antibodies and B-1 cells in filarial-infected human subjects. After antifilarial treatment, levels of IgM antibodies to ss-DNA, actin, LPS and filarial antigen increased significantly indicating a role of polyreactive naturally occurring antibodies in filarial infection. Our findings add to the existing evidence that the B-cell defect in BALB.Xid mice account for susceptibility to murine filarial infection and indicate an important role for these antibodies in providing host protection against filarial infection.