Stimulated murine peritoneal macrophages in suspension and cell culture: enzyme determinations by biochemical and histochemical means

The monoclonal antibody ER-BMDM1 recognizes a macrophage and dendritic cell differentiation antigen with aminopeptidase activity

Here we describe the reactivity of monoclonal antibody (mAb) ER-BMDM1, directed against a 160-kDa cell membrane-associated antigen (Ag) with amino-peptidase activity. The aminopeptidase recognized by ER-BMDM1 is present on various mouse macrophage (M phi) and dendritic cell (DC) subpopulations as well as on microvillous epithelia. Analysis of ER-BMDM1 Ag expression in in vitro models of M phi maturation revealed that the Ag is expressed at increasing levels upon maturation of M phi. In vivo, high level expression of the ER-BMDM1 Ag occurs after the monocytic stage of maturation, since bone marrow cells and peripheral blood monocytes are essentially ER-BMDM1 negative. Analysis of isolated-resident and elicited M phi populations showed that ER-BMDM1 recognizes a specific subpopulation of mature M phi: only some resident peritoneal and alveolar M phi are ER-BMDM1 positive, whereas virtually all thioglycollate-elicited peritoneal exudate M phi bind the mAb. In lymphoid organs, a subpopulation of M phi is recognized as well as interdigitating cells (IDC) located in T cell areas. Phenotypic analysis of isolated DC--the in vitro equivalents of IDC--from spleen and lymph nodes confirmed that the majority of this important antigen-presenting cell population expresses the ER-BMDM1 aminopeptidase. The molecular characteristics of the ER-BMDM1 Ag suggest that it may represent the mouse homolog of human CD13.

Esterase-18 (ES-18) of the house mouse (Mus musculus): biochemical characterization and genetics of an allozyme system linked to chromosome 19

This study describes the biochemical characterization, genetic variation, and linkage of a codominantly inherited murine esterase, termed ES-18. The enzyme was identified by isoelectric focusing of supernatants obtained after centrifugation of tissue homogenates and subsequent staining for esterase using either alpha-naphthyl acetate or 4-methylumbelliferyl elaidate as substrate. ES-18 exhibited an organ-specific variation of the intensity pattern of bands as seen in kidney, spleen, and macrophages, respectively. Its activity was highly sensitive to inhibition by 1 mmol.liter-1 p-chloromercuriphenylsulfonate but was resistant to bis-p-nitrophenyl phosphate. Four allozymes could be distinguished in kidney supernatants obtained from the inbred strains C57BL/10Sn (ES-18A), MOLF/Ei (ES-18B), WLL/BrA (ES-18C), and CAST/Ei (ES-18D). The enzyme is shown to be controlled by a structural locus, Es-18, which resides on chromosome 19. The gene order Ly-1 - Got-1 - 4.7 +/- 1.6 - Es-18 is suggested.

Isolation of plasma membrane from human blood monocytes. Subcellular fractionation and marker distribution

The isolation of plasma membrane from human peripheral blood monocytes is described. Monocytes were isolated by centrifugal elutriation, to eliminate an adherence step, thus minimizing functional and surface antigenic alterations to the cells. Monocytes were surface-labelled with a radiolabelled monoclonal antibody, 125I-WVH-1, and then disrupted by nitrogen cavitation. Membranes were separated according to equilibrium buoyant density by isopycnic centrifugation on a sucrose gradient. The subcellular membranes were localized using marker enzymes for the plasma membrane, 5'-nucleotidase and leucine 2-naphthylamidase (leucine aminopeptidase), and for intracellular membranes: galactosyltransferase (Golgi), arylsulfatase C (endoplasmic reticulum), monoamine oxidase (mitochondria), catalase (peroxisomes), beta-hexosaminidase and beta-glucuronidase (lysosomal vesicles) and lactate dehydrogenase (cytosol). The monoclonal antibody 125I-WVH-1 was shown to label the plasma membrane, as judged by known markers, and represents a highly specific trace label, applicable to the use of plasma membrane as an immunogen for monoclonal antibody production. The NAD-splitting enzyme, NAD+ nucleosidase, was detected and its presence on the plasma membrane was demonstrated. The subcellular localization of non-specific esterase in human mononuclear phagocytes is controversial. No evidence was found for alpha-naphthyl acetate esterase activity on the plasma membrane or in lysosomal vesicles. However, a membrane-bound esterase in fractions with properties similar to the smooth endoplasmic reticulum was detected.

Some histochemical observations on invasive cells in a myopathy induced in rats with 5-hydroxytryptamine

The enzyme cytochemistry and proportion of mononuclear cells exclusively present within degenerating muscle fibres of the soleus of rats 24 h after a single intraperitoneal injection of 5-hydroxytryptamine (5-HT) (10 mg/kg) were studied. The following enzymes displayed strong cytochemical activities within these cells: non-specific esterase (against naphthol AS-D acetate and alpha-naphthylacetate), aminopeptidase (against leucine-4-methoxy-2-naphthylamide) and dipeptidyl peptidase II. A peroxidatic activity was also present, but was found to arise from cytochrome oxidase in phagocytosed muscle mitochondria. The aminopeptidase activity in the monocytic cells increased by roughly 50% between 6 and 24 h after 5-HT administration. Dipeptidyl peptidase II was found, by the use of appropriate inhibitors, to be present in both mononuclear cells and muscle fibres and may be implicated in degrading the basal lamina of muscle fibres, thereby permitting access to the mononuclear cells. The morphological, enzyme histochemical and electron microscopical evidence suggest that the cells which invade muscle fibres in the early stages of a myopathy induced by 5-HT in rats are actively phagocytosing, mature macrophages.