Antigenic identification of chemotactic factor inactivator in normal human serum and bronchoalveolar lavage fluid.

Several proteins have been described that can modulate the activity of the complement component C5a, a potent chemoattractant for neutrophils. One of these inhibitors has been termed chemotactic factor inactivator (CFI). We hypothesized that CFI was antigenically present in normal human serum and that antigenic levels would correlate with the ability of serum to inhibit C5a. To test this hypothesis, CFI was purified from normal human serum, antibodies to CFI were developed in rabbits, and these reagents were used to develop an enzyme-linked immunoadsorbent assay to measure CFI. Sera from 32 normal volunteers were assayed for CFI and found to contain 77 +/- 29 micrograms/ml (range 17 to 137 micrograms/ml). Partially purified CFI from normal human sera was found to inhibit 61% +/- 9% (range 45% to 75%) of the ability of C5a to attract human neutrophils. Importantly, the ability of CFI to inhibit C5a-induced neutrophil chemotaxis correlated with the antigenic amounts of CFI (r = 0.68, P less than 0.05), suggesting that CFI is a major inhibitor of C5a. This was confirmed by the finding that (1) all C5a inhibitory activity coprecipitated with CFI by ammonium sulfate precipitation (45% to 65% saturation), and (2) depletion of this ammonium sulfate fraction of CFI resulted in a major loss in its ability to inhibit the chemotactic activity of C5a (57% vs. 8% inhibition, P less than 0.01). To determine whether CFI could play a role in the modulation of inflammation at tissue sites, normal bronchoalveolar lavage fluid was evaluated for the presence of CFI. CFI was identified in all fluids (mean 0.50 +/- 0.09 micrograms/mg albumin, range 0.14 to 1.43 micrograms/mg albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-2-induced chemotaxis of human T-lymphocytes.

Interleukin-2 (IL-2), a growth factor for T-lymphocytes, has been postulated to cause the accumulation of T-lymphocytes at sites of inflammation by inducing proliferation of these cells. We hypothesized that IL-2 might also serve to attract T-lymphocytes to inflammatory sites. To test this hypothesis, human T-lymphocytes were purified from the peripheral blood of normal volunteers by rosetting with neuraminidase-treated sheep red blood cells and tested for chemotactic activity by using a blind-well chamber technique. Purified IL-2 caused a greater than 20-fold attraction of T-lymphocytes compared with medium alone (P less than 0.001). This attraction was shown to be chemotactic rather than chemokinetic by checkerboard analysis. The T-lymphocyte chemotaxis could be completely inhibited by adsorption of the IL-2 with an IL-2-dependent cell line, and could be neutralized by monoclonal anti-IL-2 antibody. Further specificity of IL-2-directed chemotaxis was demonstrated by using species-specific IL-2. Mouse IL-2 was ineffective at promoting human T-lymphocyte chemotaxis. These data suggest that IL-2 may be responsible for the localized accumulation of T-lymphocytes both by causing attraction of these cells and by modulating their proliferation.