The interaction of lymphocyte surface-bound immune complexes and neutrophils

Neutrophils can be stimulated directly by a variety of stimulants resulting in the production of highly reactive oxygen derivatives. Included in these stimulants are peripheral blood lymphocytes with bovine serum albumin-anti-bovine serum albumin immune complexes (BSA-IC) or aggregated gamma-globulin (AHG) bound to their surface receptors. Through the use of chemiluminescence (CL) studies, we found that B lymphocytes preincubated with AHG stimulated neutrophils to a much greater extent than similarly preincubated T lymphocytes. Preincubated Raji cells (a B lymphoblastoid cell line) were also capable of stimulating neutrophils. We further demonstrated that after periods of mixed incubation with neutrophils, lymphocytes with surface-bound AHG did show an abnormal proliferative response to pokeweed mitogen (PWM), but not to phytohemagglutinin (PHA). This was not due to loss of cell viability, as judged by chromium release cytotoxicity assays and trypan blue exclusion, or to neutrophil enzyme release. The data suggest that neutrophils, stimulated with lymphocyte surface-bound immune complexes, are capable of producing an environment of in vitro oxidant stress. This stress, although not great enough to cause a significant decrease in lymphocyte viability, can cause impaired lymphocyte function. Physiologically, this may relate in the long term to immunologic malfunction observed in patients with high levels of circulating immune complexes.