Chromate transport in human leukocytes

Abstract

A B S T R A C T Chromium is a trace metal of importance in human physiology and, in addition, as 51-chromate, has been extensively used as a label in the study of blood cell pool sizes and intravascular kinetics. The transport characteristics of 51-chromate were investigated in normal human leukocytes. Chromate uptake is unidirectional over a 1 hr incubation with extracellular chromate concentrations up to 200 omoles/liter. Under these conditions, intracellular 51-chromium is in a form in which it is nonexchangeable. Influx is temperature sensitive with a Qio of approximately 2 and may be energy dependent since a variety of metabolic poisons strongly inhibit uptake. The unidirectional influx of chromate follows Michaelis-Menten kinetics; the maximum velocity is 52 m/moles/g dry weight of cells per min and the chromate concentration at which influx velocity is half maximal is 87 /Lmoles/liter. This transport mechanism is highly specific for chromate; other divalent tetrahedral anions only slightly inhibit influx at concentrations up to 10 times that of chromate. Metavanadate, however, competitively inhibits chromate influx at equimolar concentrations. Exposure of cells to unlabeled chromate leads to inhibition of subsequent influx of 51-chromate. It is suggested that this is due to a primary inhibitory effect of chromate on cellular energy metabolism.

Damage to Pseudohyphal Forms of Candida albicans by Neutrophils in the Absence of Serum In Vitro

“…Viability of neutrophils was determined before and after incubation with Candida using exclusion of 0.1% trypan blue. In selected experiments, neutrophils were labeled with 5'Cr (24), and release of 5mCr during incubations was measured. Degranulation of neutrophils was observed under phase contrast microscopy, and by fluorescence microscopy after staining of granules with a 1: 100,000 dilution of acridine orange in HBSS according to the method of Allison (25) and D'Arcy Hart and Young (26).…”

Quantification of neutrophil chemotaxis: A comparison of stereological and 51Cr‐labelling methods

“…The major disadvantage of the radioassay method is the potential damage to cells caused by the incubation necessary for "Cr-labelling. The uptake of s'Cr is unidirectional and in the neutrophils it complexes with intracellular proteins (12). Extracellular 5'Cr may therefore represent proteins that have either 1) been liberated from dead cells 2), passively leaked, or 3 ) sequestered from living cells.…”

HUMAN MONOCYTE AND POLYMORPHONUCLEAR LEUKOCYTE CHEMOTACTIC AND CHEMOKINETIC RESPONSES TO LEUKOTRIENE B4 AND FMLP

“…The PMN were judged morphologically and a purity of more than 96% was obtained. Following isolation, the MO and PMN were labelled with "Cr as described by Lilien et al (20) and adjusted to a final concentration of 2.0 x lo6 MO/ml and 3.5 x lob PMN/ ml in medium RPMI 1640 supplemented with 1% heatinactivated foetal calf serum (Medium). The labelled cell suspension was applied in a volume of 250 pl in the upper compartment of the chemotactic chamber of blind well type (Nuclepore Corp., USA).…”