Levels of gamma interferon and interleukin-4 are inversely related to the levels of their corresponding autoantibodies in patients with lower respiratory tract infection

To study the involvement of cytokines and their corresponding autoantibodie s (Aabs) in inflammatory mechanisms in patients with lower respiratory trac t infections, blood samples were taken from patients at the time of admissi on to the hospital and before treatment. Cell-released capturing enzyme-lin ked immunosorbent assay was used to measure the levels of gamma interferon (IFN-gamma) and interlenkin-4 (IL-4) produced spontaneously by peripheral m ononuclear cells (PMNC). ELISA was used to measure Aabs to these cytokines in sera. The levels of both cytokines were inversely related to the levels of their corresponding Aabs. While a high level of IFN-gamma was observed t ogether with a low level of anti-IFN-gamma Aab, decreased IL-4 levels were observed with increased levels of Aabs to IL-4. Immunoglobulins were purifi ed, digested to obtain Fab fragments, and tested for specificity and cross- reactivity. The Aabs and their Fab fragments were tested in cytokine biolog ical assays and showed neutralizing effects. Our data demonstrated increase d levels of the proinflammatory cytokine IFN-gamma and decreased release of the anti-inflammatory cytokine IL-4 during early presentation of lower res piratory tract infection. The levels of these cytokines were inversely rela ted to the levels of their corresponding Aabs that exhibited regulatory eff ects on the cytokine biological function in vitro.