21.1.1, a novel activation marker of T and B cells

Immunophenotyping of murine peritoneal macrophages and lymphocytes by flow cytometry

Peritoneal cells include mainly macrophages and both T and B lymphocytes. We describe a simple procedure to analyze by flow cytometry the antigens expressed on macrophage and/or lymphocyte membranes. F4/80 and CR3 macrophage antigens were detected with anti-F4/80 and anti-Mac-1 monoclonal antibodies (mAb) respectively, CD4 and THY1.2 T lymphocyte antigens with GK1.5 and J1j mAbs respectively, B CD5 lymphocytes were identified with LY1.2 mAb and Fc gamma RII/Fc gamma RIII were detected with 2.4G2 mAb.

Preparation and characterization of a new monoclonal antibody CAF7 specific for a leukocyte activation antigen

A new murine hybridoma, CAF7, is raised using as an antigen the T-leukemic cell line CEM. It produces a monoclonal antibody (mAb) specific for an activation antigen on human lymphocytes. CAF7 stains monocytes, very weakly resting lymphocytes, and granulocytes, part of the thrombocytes, but not erythrocytes. After activation with phytohemagglutinin (PHA), CAF7 expression on peripheral lymphocytes rises as early as 5 hr post stimulation and 72-hr blasts express it at a considerable level. The cell lines Jurkat, CEM, MOLT4, Raji, Reh, K562, and MONOMAC6 are positive for CAF7. CAF7 immunoprecipitated an antigen, which when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions migrated as a single band with a molecular weight of 120-140 kD. Under reducing conditions, it appears as two bands at 90-100 and 40 kD. The pattern of expression and the biochemical characteristics of CAF7 do not match any of the clusters defined in the Leukocyte Typing Workshops, but do resemble that of a previously described antigen, 4F2.

Mouse peritoneal macrophages: characterization of functional subsets following Percoll density gradients

Mouse resident peritoneal cells were separated into twelve fractions on Percoll gradients according to their specific density and were thoroughly characterized by Giemsa staining, some biochemical assays, immunophenotyping and phagocytic tests. Among these fractions, the macrophages were mainly represented in 7 subsets of 1.073 to 1.104 g/ml densities. The results of this study emphasize that resident peritoneal macrophages of primo-explantation can be divided into two distinct subpopulations with separate functions, related to the stage of cell maturity. In fact, our results show that one macrophage subpopulation is rich in immature cells, characterized by their peroxidative activity, the expression of F4/80 antigen, Mac-1 and Fc receptors, in correlation with their high specific density; the second subpopulation contains mature macrophages (lower percentage of peroxidase-positive cells) with lower densities and a lower level of expression of the above-mentioned molecules. Antibody-dependent and antibody-independent bacterial phagocytosis, the phagocytic index and Fc gamma RII rosetting increased together with the cell density, and were elevated in the immature cell subpopulation. T and B lymphocytes were also identified in all the macrophage subsets, but in a low proportion.