Antibody

About: Antibody is a research topic. Over the lifetime, 113941 publications have been published within this topic receiving 4130181 citations. The topic is also known as: Ab & antibodies.

Identification of the membrane glycoprotein that is the C3b receptor of the human erythrocyte, polymorphonuclear leukocyte, B lymphocyte, and monocyte.

Abstract: A human erythrocyte membrane glycoprotein of 205,000 mol wt (gp205) has been identified as the C3b receptor of the erythrocyte, polymorphonuclear leukocyte (PMN), B lymphocyte, and monocyte. Initially, gp205 was sought and characterized as a constituent of the human erythrocyte membrane that can impair activation of the alternative complement pathway by inducing loss of function of the properdin-stabilized amplification C3 convertase (C3b,Bb,P) through displacement of Bb from C3b and by promoting cleavage-inactivation of C3b by C3b inactivator. These inhibitory activities of gp205 suggested that this membrane glyeoprotein had an affinity for C3b and prompted an analysis of its possible identity as the C3b receptor of human peripheral blood cells. The F(ab')2 fragment of rabbit IgG anti-gp205 inhibited the formation of rosettes with sheep EC3b of human erythroeytes, B lymphocytes, monocytes and PMN in a dose-response manner; the 50 percent inhibitory doses were 0.13/mug/ml, 0.90 mug/ml, 1.25 mug/ml, and 1.20 mug/ml of F(ab')2, respectively. Anti-gp205 did not impair the formation of rosettes by monocytes and B lymphocytes with sheep EC3bi or with EC3d. Scatchard analysis of the number of specific (125)I-F(ab')(2) anti-gp205 binding sites/cell revealed 950 sites/erythrocyte, 21,000 sites/cell of B lymphocyte preparation, 57,000 sites/PMN, and 48,000 sites/monocyte, indicating that the higher concentrations of antibody that had been required for inhibition of rosette formation by the nucleated cells reflected larger numbers of receptors on these cells. Direct evidence for the identity of gp205 as the C3b receptor of the four cell types was obtained when detergent-solubilized membrane proteins of the surface-radioiodinated cells were reacted with anti- gp205 and the immunoprecipitate was analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. In each instance, the antigenic material reacting with anti-gp205 represented a single protein with an apparent 205,000 mol wt. Thus, gp205 is the C3b receptor of human erythrocytes, PMN, B lymphocytes, and monocytes.

Tumoricidal activity of a novel anti-human DR5 monoclonal antibody without hepatocyte cytotoxicity

Abstract: A novel anti-human DR5 monoclonal antibody, TRA-8, induces apoptosis of most tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-sensitive tumor cells both in vitro and in vivo. In contrast to both the membrane-bound form of human TRAIL, which induced severe hepatitis in mice, and the soluble form of human TRAIL, which induced apoptosis of normal human hepatocytes in vitro, TRA-8 did not induce significant cell death of normal human hepatocytes. However, both primary hepatocellular carcinoma cells and an established liver cancer cell line were highly susceptible to the killing mediated by TRA-8. We show here that elevated levels of cell-surface expression of DR5 and increased susceptibility to DR5-mediated apoptosis are characteristics of malignant tumor cells. In contrast, DR5 alone is not sufficient to trigger apoptosis of normal hepatocytes. Therefore, selective, specific targeting of DR5 with an agonistic antibody might be a safe and effective strategy for cancer therapy.

B lymphocytes are essential for the initiation of T cell-mediated autoimmune diabetes: analysis of a new "speed congenic" stock of NOD.Ig mu null mice.

Abstract: The T lymphocytes mediating autoimmune destruction of pancreatic beta cells in the nonobese diabetic (NOD) mouse model of insulin-dependent diabetes mellitus (IDDM) may be generated due to functional defects in hematopoietically derived antigen-presenting cells (APC). However, it has not been clear which particular subpopulations of APC (B lymphocytes, macrophages, and dendritic cells) contribute to the development and activation of diabetogenic T cells in NOD mice. In the current study we utilized a functionally inactivated immunoglobulin (Ig) mu allele (Ig mu null) to generate a "speed congenic" stock of B lymphocyte-deficient NOD mice that are fixed for linkage markers delineating previously identified diabetes susceptibility (Idd) genes. These B lymphocyte NOD.Ig mu null mice had normal numbers of T cells but were free of overt IDDM and insulitis resistant, while the frequency of disease in the B lymphocyte intact segregants was equivalent to that of standard NOD mice in our colony. Thus, B lymphocytes play a heretofore unrecognized role that is essential for the initial development and/or activation of beta cell autoreactive T cells in NOD mice.

Hodgkin disease: Hodgkin and Reed-Sternberg cells picked from histological sections show clonal immunoglobulin gene rearrangements and appear to be derived from B cells at various stages of development.

Abstract: Hodgkin disease (HD) is characterized by a small number of putative malignant cells [Hodgkin and Reed-Sternberg (HRS) cells] among a background of lymphocytes and histiocytes. The lineage of HRS cells is still elusive and a clonal origin of these rare cells has not formally been demonstrated. We isolated HRS cells by micromanipulation from histological sections of three cases of Hodgkin lymphoma (each representing a distinct subtype of the disease) and analyzed individual cells for immunoglobulin variable (V) gene rearrangements by PCR. In each of the three cases a single heavy-chain V (VH) (and in one case, in addition, a kappa light-chain) gene rearrangement was amplified from the HRS cells, identifying these cells as members of a single clone. A potentially functional VH rearrangement was obtained from a case of nodular sclerosis HD. Somatic mutations and intraclonal diversity in the VH genes indicate a germinal center B-cell origin of the HRS cells in a case of lymphocyte-predominant HD, whereas in a case of mixed-cellularity HD the sequence analysis revealed only nonfunctional V gene rearrangements, suggesting a pre-B-cell origin. This indicates that HRS cells can originate from B-lineage cells at various stages of development.