IODINATION BY HUMAN POLYMORPHONUCLEAR LEUKOCYTES - RE-EVALUATION

Abstract

The conversion of iodide to a trichloroacetic acid-precipitable form (iodination) by polymorphonuclear leukocytes (PMN) was re-evaluated as a measure of neutrophil function. Optimum conditions are described which result in an iodination value for normal cells during the phagocytosis of zymosan of 64.1 .+-. 13.2 (SD) nmol/107 PMN/h. Iodination is inhibited by agents which decrease phagocytosis, inhibit myeloperoxidase-catalyzed reactions or degrade H2O2 and is stimulated by superoxide dismutase, an enzyme which catalyzes the conversion of the superoxide anion to O2 and H2O2. When patients'' cells and normal serum are employed, the iodinating capacity of the patients'' cells is evaluated. It is low in patients with myeloperoxidase deficiency and chronic granulomatous disease. An intermediate value was observed in a carrier of chronic granulomatous disease. When normal cells and patients'' serum are employed, the iodination reaction is an indirect measure of the opsonic activity of the patients'' serum. The decreased opsonic activity for zymosan of human sera deficient in the 4th or 3rd component of complement was thus demonstrated. Measurement of iodination is a convenient and sensitive screening test for cellular or humoral abnormalities of the phagocytic process.