Human antibodies isolated from plasma by affinity chromatography increase the coxsackievirus B4-induced synthesis of interferon-α by human peripheral blood mononuclear cells in vitro

Coxsackievirus B4 (CVB4) can be found in circulating blood of patients; however, the interaction of CVB4 with peripheral blood mononuclear cells (PBMCs) is poorly understood. CVB4 induced low levels of IFN-α synthesis in PBMCs from healthy donors. In contrast, preincubation of infectious CVB4 with plasma from these donors containing anti-CVB4 antibodies strongly enhanced the synthesis of IFN-α. IgG obtained from plasma by chromatography formed immune complexes with CVB4 and increased significantly the CVB4-induced production of IFN-α by PBMCs. These antibodies did not have a neutralizing effect on CVB4 infection of Hep-2 cells. The role of CVB and adenovirus receptor (CAR), FcγRII and FcγRIII in the increased synthesis of IFN-α induced by CVB4 preincubated with IgG was shown by inhibition with specific antibodies. The major interferon-α-producing cells in response to CVB4–IgG complexes were CD14+ cells and monocyte-enriched PBMCs. With the latter, detection of IFN-α by immunostaining was positive whereas in monocyte-depleted PBMCs it was not. This study shows that CVB4-induced synthesis of IFN-α by PBMCs can be enhanced by an antibody-dependent mechanism through interactions between the virus, non-neutralizing antivirus antibodies, FcγRII and III and CAR.