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

Summary 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.