Bruce E. Seligmann

Recent Advances in Chronic Granulomatous Disease

: Chronic granulomatous disease represents a group of disorders of phagocytic cell oxidative metabolism involving recurrent infections with catalase-positive microorganisms and chronic inflammation. Genetic heterogeneity and phagocyte abnormalities, including enzyme deficiencies, abnormal elicited membrane potential changes, abnormal acidification of the phagocytic vacuole, and deficiencies of an electron transport cascade, have been associated with its pathogenesis. In addition, recently we have shown abnormal neutrophil C3b-receptor expression, antibody-dependent cellular cytotoxicity, and abnormal microtubule metabolism (tyrosinolation of the alpha-chain of tubulin). Fourteen patients with the disease who were followed at the National Institutes of Health had life-threatening infections, on average, once every 9.6 months. In most of the 119 febrile episodes seen in these patients, no infectious agent was found. Retrospective studies indicated that prophylactic antibiotic therapy, particularly with trimethoprim-sulfamethoxazole, significantly prolonged disease-free intervals to greater than 40 months (p less than 0.05). In serious, life-threatening infections, leukocyte transfusions have been used in therapy. Transfused leukocytes localize and persist at infectious sites, and the clinical efficacy of leukocyte transfusions has been suggested.

Interaction of chemotactic factors with human polymorphonuclear leukocytes: Studies using a membrane potential-sensitive cyanine dye

SummaryChanges in the fluorescence intensity of the dye 3-3′ dipentyloxacarbocyanine were measured in suspensions of purified human peripheral blood polymorphonuclear leukocytes (PMNs) during exposure to the chemotactic factors N-formyl-methionylleucyl-phenylalanine (f-met-leu-phe) and partially purified C5a. Incubation of PMNs with dye resulted in a stable fluorescence reflecting the resting membrane potential of the cell. Exposure of PMNs to dye did not affect stimulated chemotaxis or secretion. The mechanism of cell-associated dye fluorescence involved solvent effects from partitioning of the dye between the aqueous incubation medium and the cell and not dye aggregation, Chemotactically active concentrations of f-met-leu-phe (5×10−9m or greater) produced a biphasic response characterized as a decrease followed by an increase in fluorescence. No fluorescence response was seen in lysed PMNs, and no response was elicited by an inhibitor of f-met-leu-phe binding (carbobenzoxy-phenylalanyl-methionine). The ability of several other synthetic peptides to elicit a fluorescence response corresponded to their effectiveness as chemotactic agents. Although the first component of the response suggested a depolarization, it was not influenced by variation in the external concentration of sodium, potassium, chloride, or calcium, and could not be characterized as a membrane potential change. The second component of the response, which was inhibited by both Mg2+ (10mm)-EGTA (10mm) and high external potassium, was compatible with a membrane hyperpolarization. The data indicate that chemotactic factors produce changes in dye fluorescence which can, at least in part, be attributed to a hyperpolarizing membrane potential change occurring across the plasma membrane.

Alteration of Macrophage and Monocyte Membrane Potential by Chemotactic Factors

Macrophages exhibit a number of membrane-related activities associated with specific membrane receptors as well as with membrane turnover. To understand the ionic events occurring during these activities, we have studied the electrophysiological properties of macrophages. In this report we review and extend our findings on the electrophysiology of macrophages before and during activation by chemotactic factors, and also present data on potential changes occurring during monocyte activation as assessed with the membrane potential sensitive cyanine dye, dipentyloxacarbocyanine [di-0-C5 (3)].