The effects of citrate on the adherence of neutrophils to nylon fibers in vitro.

The therapeutic effect of citrate on alkali-burned eyes is thought to be the result of inhibition of PMN activities while ascorbate apparently stimulates the production of new collagen by scorbutic fibroblasts. Attachment of PMNs to the vascular endothelium is the initial PMN response to mediators and must occur before diapedesis and chemotaxis can produce a tissue infiltrate. The present study was undertaken to test the effects of citrate or ascorbate on the in vitro adherence of resting and leukotriene B4 (LTB4)-treated PMNs. Citrate preincubation of resting or LTB4-treated PMNs inhibited adherence in a dose-dependent manner. Inhibition of LTB4 augmented adherence by 12 mM citrate was effectively reversed by the addition of Ca2+ and Mg2+ (6 mM each). Ascorbate had no significant effect on the adherence of resting or LTB4 treated PMNs. In addition we wished to test the effectiveness of the breakdown product(s) from alkali burned collagen (Type 1) as an augmentor of adherence because of its effectiveness as a locomotory and respiratory burst stimulant. These break-down product(s) had no effect on the adherence of resting or LTB4-treated PMNs unless bovine serum albumin (BSA) was omitted from the incubation mixture. In the absence of BSA, these breakdown products inhibited both types of adherence in a dose-dependent manner with dilutions from 1:10 to 1:1000. This inhibition is probably not clinically meaningful since PMN adherence takes place in the vasculature where BSA would always be present. As a consequence of citrate inhibition of adherence in vivo, PMNs would be denied access to the injury site, trapping them in a resting state within the circulatory system.