In vitro studies of the adhesive interactions of neutrophil granlocytes

The adhesion of rabbit neutrophil granulocytes to cultured pig atortic endothelial cells, to serum coated glass and to each other has been studied under a variety of conditions using adhesion-to-substratum and aggregation assays. Under standard conditions, in the presence of balanced salt solution (BSS) and serum alone a number of variables were found to alter the level of adhesion to serum coated glass and endothelium. Changes in time of incubation, cell number, serum concentration and assay volume all altered the observed level of adhesion. Adhesion to serum coated glass was higher than to endothelial cells. The inflammatory mediators histamine and 5-hydroxytryptamine (5-HT) had slight inhibitory effects while bradykinin had no significant effect on adhesion. Anti-inflammatory drugs were examined. Aspirin, hydrocortisone and colchicine all reduced adhesion. Prednisolone, indamethacin and amino-n-caproic acid had no significant effect on adhesion. A range of miscellaneous agents were tested for effects on adhesion. These were aminophylline, formalin, heparin and several sugars and had slight, if any, inhibitory effects on adhesion. A range of chemotactic factors were shown to have diverse effects on adhesion. At chemotactically optimal concentrations, s-casein casein, alkali-denatured human serum albumin (HSA) and several synthetic n-formyl-di-and tri-peptides reduced neutrophil adhesion after short (≤30 min.) periods of incubation. Detailed study of one such peptide, n-formyl methionyl-leucyl-phenylalanine revealed that at higher than chemotactic optimum concentrations, neutrophil adhesion was less reduced and that after longer times of incubation, was increased. An inverse relationship was observed between neutrophil adhesiveness and locomotion. This was shown at various concentrations and times. In parallel with increased neutrophil adhesion, an increase in lysosomal enzyme secretion was demonstrated. This, and the adhesive increase were inhibited by the presence of hydrocortisone sodium succinate. No increases in endothelial adhesiveness induced by chemotactic factors were ever observed. It was concluded that the adhesive changes observed were not related to the process of margination in vivo but that they may be related to the pattern of neutrophil movement in vivo