Biomaterial Database

Receptors for IgM on human lymphocytes. III. Specificity of receptors. 1979

M W Fanger, and P M Lydyard

Receptors for the Fc portion of IgM (RFcmu) can be detected on a large percentage of human peripheral lymphocytes. To approach an understanding of the function of these receptors we have examined the relative efficiencies of different preparations of human IgM and their F(c)5 mu fragments in binding to RFcmu. This was measured by blocking rosette formation between lymphocytes and IgM-sensitized ox erythrocytes (EAmu). IgM from pooled normal human serum completed blocked formation of IgM rosettes (EAmu-RFC) at much lower concentrations than IgM preparations from individual Waldenström's macroglobulinaemic patients (WM). The differences in effectiveness of these IgM preparations in inhibiting EAmu-RFC suggested the existence of receptors for subclasses of IgM on different subpopulations of human lymphocytes. F(c)5 mu fragments of IgM were more effective in blocking EAmu-RFC than the parent molecule, which was in turn more efficient than the 8S subunit. These results indicate that F(c)5 mu may have more Fc regions exposed per molecule for binding to the matrix of RFcmu than pentameric IgM and that Fc multivalency may be important for the stable binding of IgM to RFcmu.

UI	MeSH Term	Description	Entries
D007075	Immunoglobulin M	A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally was called a macroglobulin.	Gamma Globulin, 19S,IgM,IgM Antibody,IgM1,IgM2,19S Gamma Globulin,Antibody, IgM
D007141	Immunoglobulin Fc Fragments	Crystallizable fragments composed of the carboxy-terminal halves of both IMMUNOGLOBULIN HEAVY CHAINS linked to each other by disulfide bonds. Fc fragments contain the carboxy-terminal parts of the heavy chain constant regions that are responsible for the effector functions of an immunoglobulin (COMPLEMENT fixation, binding to the cell membrane via FC RECEPTORS, and placental transport). This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.	Fc Fragment,Fc Fragments,Fc Immunoglobulin,Fc Immunoglobulins,Ig Fc Fragments,Immunoglobulin Fc Fragment,Immunoglobulins, Fc,Immunoglobulins, Fc Fragment,Fc Fragment Immunoglobulins,Fc Fragment, Immunoglobulin,Fc Fragments, Ig,Fc Fragments, Immunoglobulin,Fragment Immunoglobulins, Fc,Fragment, Fc,Fragments, Ig Fc,Immunoglobulin, Fc
D008214	Lymphocytes	White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.	Lymphoid Cells,Cell, Lymphoid,Cells, Lymphoid,Lymphocyte,Lymphoid Cell
D011961	Receptors, Fc	Molecules found on the surface of some, but not all, B-lymphocytes, T-lymphocytes, and macrophages, which recognize and combine with the Fc (crystallizable) portion of immunoglobulin molecules.	Fc Receptors,Fc Receptor,Receptor, Fc
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D012397	Rosette Formation	The in vitro formation of clusters consisting of a cell (usually a lymphocyte) surrounded by antigenic cells or antigen-bearing particles (usually erythrocytes, which may or may not be coated with antibody or antibody and complement). The rosette-forming cell may be an antibody-forming cell, a memory cell, a T-cell, a cell bearing surface cytophilic antibodies, or a monocyte possessing Fc receptors. Rosette formation can be used to identify specific populations of these cells.	Immunocytoadherence,Formation, Rosette,Formations, Rosette,Immunocytoadherences,Rosette Formations