Definition by CB12 monoclonal antibody of a differentiation marker specific for human monocytes and their bone marrow precursors

Generation and Characterization of a Murine Monoclonal Antibody Specific for the Human T1-Cd5 Molecule

Murine monoclonal antibodies (MoAbs) have found widespread applications in the characterization of the molecular and functional features of lymphocyte differentiation antigens. The present paper summarizes the results of our work dealing with the production and selection of a murine MoAb recognizing a molecule expressed during the whole differentiative life of T lymphocytes. The MoAb CB01 resulted to be specific for an apparently unique epitope of the T-cell specific membrane glycoprotein T1-CD5.

Microplate selection technique (MPST). A new method for selecting mouse transfectants expressing human gene products

This paper examines the analytical power of fluorescence activated cell sorting and immunorosetting technique as compared with the newly devised microplate selection technique in identifying transfected murine L cells expressing human surface molecules. The microplate selection technique relies on the mechanical transfer of transfected cells to a terasaki microplate, where an indirect immunofluorescence assay is carried out. It is a simple procedure not requiring costly equipment and with a detection capacity equivalent to that of the fluorescence activated cell sorter. The microplate selection technique proved to be sensitive enough to detect all the transfectants produced during the present study.

Functional changes of monocytes due to dialysis membranes

The functional effects directly induced by dialysis membranes on peripheral monocytes were analyzed in a plasma-free model of simulated dialysis using Cuprophan, cuprammonium rayon, polyacrylonitrile, polymethylmetacrilate and polysulphone membranes. A severe reduction of monocyte phagocytosis of IgG-coated erythrocytes was found by using Cuprophan and cuproammonium rayon. The cytofluorimetric analysis of several cell surface receptors, involved in the immune phagocytosis and recognizable by five quoted monoclonal antibodies, did not reveal any significant change. The defective phagocytosis of the IgG-coated erythrocytes by monocytes, due to the exposure to cellulose-derived membranes, was paralleled by an impaired interiorization of heat-aggregated human immunoglobulins, as analyzed by electron microscopy. The cell membrane binding of aggregated immunoglobulins was found to be unaffected. The defect was associated to a remarkably depressed generation of reactive oxygen species after Zymosan stimulation. Therefore, the defective immune phagocytosis induced by exposure of monocytes to cellulosic membranes was not due to a receptor rearrangement or an impaired binding of ingestible particles, but to a reduced internalization capacity probably related to an energy source exhaustion (as shown by the lack of response to stimuli able to induce oxidizing species production). These features are similar to those described in monocytes from acute systemic lupus erythematosus patients.

Generation and selection of monoclonal antibodies identifying surface molecules discriminating between fetal and adult fibroblasts

The present report describes the reactivity of two murine monoclonal antibodies, i.e., CB11 and CB43, the first obtained by using embryonic material as immunizer and the second elicited against a human cell line. These reagents recognize two distinct molecules marking a peculiar differentiation stage on fetal/embryonic fibroblasts. The first structure is a single chain of 14.5 kd, the second one a heterodimer of 40-80 kd. Even if these reagents are not strictly fibroblast restricted, translineage expression does not diminish the medical relevance of the reagents; in fact, they may have application in prenatal diagnostics and amniocentesis testing, in which it is necessary to discriminate between fetal and maternal cells.

Identification of a new epitope of the 4F2/44D7 molecular complex present on sarcolemma and isolated cardiac fibers

The murine monoclonal antibody (mAb) CB43, raised against the K-562 erythroleukemia line, reacts with monocytes, tissue macrophages, thymocytes and with all the human lines tested but not with resting lymphocytes, large granular lymphocytes, granulocytes and erythrocytes. However, activated lymphocytes and natural killer cells express the CB43 antigen. Embryonic and fetal fibroblasts are positive, while adult fibroblasts are negative. Proximal convoluted tubules in kidney, epithelial cells in esophagus and breast, and sarcolemma in skeletal muscle are reactive with mAb CB43. This antibody can also bind to isolated guinea pig cardiac myocytes, and, furthermore, can induce a transient inotropic effect on isolated atria. The reactivity with different cell and tissue types and the functional effects of the CB43 mAb were reminiscent of the 4F2/44D7 antibodies, shown previously to block Na+/Ca2+ exchange in heart and skeletal muscle. Co-immunoprecipitation studies with CB43 and 44D7 mAb, using radiolabeled Daudi cells, revealed co-migration of polypeptides of 87 and 38 kDa. However, the epitope recognized by CB43 is not present on the human heavy chain which bears the 44D7/4F2 epitope as demonstrated by the lack of reactivity of CB43 mAb with mouse L cells transfected with the 4F2 heavy chain gene. Thus, CB43 represents a newly described epitope present on the human light chain or dependent on the conformation of the human dimer.

A murine monoclonal antibody strictly reactive with human peripheral blood monocytes

We have produced and characterized a novel murine monoclonal antibody (LAM7) of IgG1 isotype which appears specific for peripheral blood monocytes (PBM) on the basis of histochemical and functional studies. By indirect immunofluorescence, including FACS analysis, the antibody reacts with 90 +/- 6% of PBM and with monocytic leukemias, while it is totally unreactive with B and T lymphocytes, platelets, granulocytes, peripheral macrophages, dendritic cells, large granular lymphocytes, and nonmonocytic leukemias. The antigen-presenting capacity of peripheral blood mononuclear cells is abolished by treatment with MoAb LAM7 in an antiglobulin-complement-mediated cytotoxicity test, and restored by addition of purified PBM. The progressive disappearance of the antigen recognized by LAM7 from PBM within approximately 3 days in culture, and its absence from both bone marrow precursors and tissue macrophages, define it as a line-specific and stage-specific differentiation.

Functional and molecular characterization by the CB04 monoclonal antibody of a cell surface structure exerting C3-complement receptor activity

CB04 monoclonal antibody which reacts with an epitope of a surface molecule expressed on human monocytes has been elicited using peripheral blood lymphocytes as immunizer. The characterization of the monoclonal antibody examined at the phenotypic, molecular, and functional levels indicates that the CB04 antibody defines a structure present on monocytes, tissue macrophages, B cells, polymorphonucleates, and erythrocytes. The molecular weight (220 kD), the tissue distribution in health and disease conditions, and the involvement in relevant biological processes indicate that the CB04 structure is the receptor for the C3b fragment of the complement. The binding of the antibody to the cell surface induces inhibition of the C3bi receptorial function.