Antirheumatic drug effects on neutrophil response to chemotactic factors: a comparison of analytical techniques.

A recently reported technique employing the leukotactic index which represents all migrating cells in vitro neutrophil chemotaxis systems, was compared to the leading front technique for assaying antirheumatic drug effects on this important neutrophil function. Normal human neutrophils were treated with therapeutic concentrations of aspirin, gold sodium thiomalate, D-penicillamine, and azathioprine. The responses of these cells and of control cells to neutrophil-immune complex-serum-derived chemotactic factors were assayed in Boyden chambers. Significant (P less than 0.05) inhibition was observed by the leading front technique only for D-penicillamine at high concentrations. Significant (P less than 0.01) inhibition was seen with D-penicillamine at therapeutic plasma levels with the leukotactic index technique. Gold sodium thiomalate and aspirin at high concentrations also produced significant (P less than 0.01 and P less than 0.05) inhibition of chemotaxis as assayed by the leukotactic index procedure. Azathioprine had no significant effects when studied with either technique. These results indicate that the leukotactic index may be a more sensitive technique for quantitating neutrophil migration in response to chemotactic factors and may therefore provide useful additional information for determining the effects of antirheumatic drugs on this important neutrophil function.