Premium
Identification and characterization of human neutrophil carbonic anhydrase
Author(s) -
Campbell Andrew R.,
Andress Dennis L.,
Swenson Erik R.
Publication year - 1994
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.55.3.343
Subject(s) - carbonic anhydrase , isozyme , extracellular , biology , cytosol , biochemistry , intracellular , cell culture , microbiology and biotechnology , bicarbonate , enzyme , red blood cell , biological activity , endocrinology , in vitro , genetics
Many functions of polymorphonuclear leukocytes (PMNs) appear to alter and be affected by changes in the intracellular and/or extracellular acid‐base milieu, suggesting that carbonic anhydrase (CA) may be important. Although small amounts of CA activity in PMNs have been reported, it has not been characterized fully. We therefore studied isolated mature circulating human PMNs and cultured HL‐60 cells, an undifferentiated myelopoietic cell line, and compared these to human red cells (RBCs) for CA activity. Activity and sulfonamide inhibition were measured by a modified micromethod assay. Isoenzyme and total CA concentrations were determined by radioimmunoassay for human isozyme CA I, differential inhibition by MK‐927, inhibition by 0.2% sodium dodecyl sulfate (SDS), and quantitative sulfonamide binding. Total CA activity (units/10 6 cells) was 0.04 in PMNs, 0.06 in HL‐60 cells, and 0.62 in RBCs. Human PMNs have a total CA concentration of 1.3 μ M, of which 0.9 μ M is CA I and the remainder is CA II. Total loss of CA activity with 100 μ M ethoxzolamide and 0.2% SDS ruled out significant CA III or CA IV activity. Subcellular fractionation of PMNs revealed that all CA activity was cytosolic. The absence of CA activity in mitochondrial and microsomal membrane fractions argues against any mitochondrial CA V or membrane‐bound CA IV contribution to total CA activity. Neutrophils contain both CA I and II isozymes in roughly the same proportion as RBCs but at much lower concentrations, suggesting that in the course of maturation the CA content of neutrophils is regulated differently from that in erythrocytes. J. Leukoc. Biol . 55: 343–348; 1994.