Lnterleukin-8 and neutrophil leucocytes: Adhesion, spreading, polarisation, random motility, chemotaxis and deactivation in assays using ‘sparse-pore’ polycarbonate (nuclepore) membranes in the Boyden Chamber

Adhesion, spreading, chemotaxis and deactivation of chemotactic responses of separated human peripheral blood neutrophil leucocytes under the influence of interleukin-8 (IL-8) were tested using a previously described Boyden chamber-type method involving ‘sparse-pore’ polycarbonate (Nuclepore) filtration membrane. The random motilities of neutrophils in similar concentrations of IL·8 were tested using corresponding chambers with polycarbonate membranes of standard pore densities. In addition, polarisation of neutrophils in suspension in various concentrations of IL-8, and the possibility of deactivation of this polarisation response by IL-8 itself or by N-formyl-methionyl-leucyl-phenylalanine (FMLP) were examined. Neutrophils exhibited maximum chemotaxis to IL-8 in a concentration of 100 ng/ml, and to a degree which was similar to the maximum response to FMLP (10–7M). This chemotactic response to IL-8 was markedly reduced by pretreatment of the cells with either 100 ng/ml IL-8 (deactivation) or 10–7M FMLP (cross-deactivation). On the other hand, the chemotactic response of the neutrophils to FMLP was reduced by pretreatment with FMLP but was not deactivated by pretreatment with IL-8 (i.e. deactivation but not cross-deactivation). Neutrophils in suspension were maximally polarised by 100 ng/ml IL-8, and to lesser degrees by 1,10 and 1,000 ng/ml IL-8. The detailed morphology of the polar cells was not distinguishable from that induced by 10–8M FMLP. Pretreatment of the cells with either IL-8 or FMLP resulted in no reduction of polarisation in response to subsequent exposure to either agent (i.e. neither deactivation nor cross-deactivation). No effects of IL-8 on adhesion, spreading or random motility of neutrophils on the polycarbonate membranes were detected.