NEUTROPHIL ALKALINE-PHOSPHATASE ACTIVITY INCREASE IN BACTERIAL-INFECTIONS IS NOT ASSOCIATED WITH A GENERAL INCREASE IN SECRETORY VESICLE MEMBRANE-COMPONENTS

The content of alkaline phosphatase (ALP) was determined in neutrophil s isolated from patients with acute bacterial infections by a standard enzyme assay. Compared with control cells, patient cells exhibited ab out a fivefold increase in ALP activity. There was no difference betwe en the ALP K-m values of control and patient cells, which indicates th at the elevated activity in patient cells was due to the presence of i ncreased amounts of the enzyme. The ALP isozyme in both cell types was determined to be the tissue-unspecific ALP. The fact that much of the ALP activity was measurable only in the presence of detergent suggest ed that the enzyme was localized in the secretory vesicles, a putative reservoir of plasma membrane components. The amount and subcellular d istribution of two other secretory vesicle membrane proteins, i.e., cy tochrome b and complement receptor 3, were not altered; hence, we conc lude that there was no general increase in amounts of secretory vesicl e membrane constituents in the patient cells.