Inhibiting Effects of Human Plasma and Serum on Neutrophil Random Migration and Chemotaxis

Various authors have associated increased susceptibility to infectious diseases in certain patients to inhibitors of neutrophil chemotaxis demonstrable in serum or diluted plasma of these patients. The present experiments showed, however, that serum and diluted plasma but not undiluted plasma from normal human donors consistently inhibited chemotactic migration of autologous human neutrophil granulocytes. Therefore, the presence of such inhibitors in the circulating blood can only be assessed by the evaluation of undiluted plasma. The findings suggest that the experimental conditions which have been used in the past to demonstrate such inhibitors in the circulating blood of patients with increased susceptibility to infections are inadequate, and results need reexamination. The inhibitors affect random locomotion and chemotaxis of neutrophil granulocytes but not phagocytosis or the metabolic burst resulting in nitroblue—tetrazolium reduction. On the other hand, phagocytosis of Staphylococcus albus rendered neutrophils chemotactically unresponsive. The significance of so-called cellular defects of neutrophil chemotaxis in such patients is also considered.