DEPENDENCE OF NEUTROPHIL ACTIVATION ON CELL-DENSITY AND ADHESION

Upon an increasing cell density human neutrophils develop more cell-to -cell contacts in conjunction with an increase in the pH(i). These cha nges are accompanied by decreased superoxide formation after adherence , and a decrease in the total amount of 5-lipoxygenase products after various stimuli. Among the various arachidonate metabolites, leukotrie ne formation remained almost constant but the yield in 5-HETE decrease d. This drop in could account for the decrease in total 5-lipoxygenase products observed when the cell density increased. We conclude that c ellular signalling can be affected by an increase of cell-cell interac tions. Whether the increase in cellular pH is a cause or consequence o f such contact inhibition has yet be answered.