The complete variable region sequences from ten antibodies and two myeloma proteins binding alpha-1,3 dextran have been determined. The diversity patterns of these homogeneous antibody molecules suggest that the variable regions of heavy chains are encoded by separate variable (V) and joining (J) gene segments. The most striking feature of these data is the extensive sequence variability of a region that we denote the D (diversity) segment which is located at the junction between the V and J segments in the centre of the third hypervariable region. The D segment diversity may arise from a novel somatic mutational mechanism or may be encoded by multiple D gene segments. For the first time, the amino acid sequence correlates of several V region idiotypes are determined.
For the first time V-region amino acid sequence differences have been correlated with the expression of cross-reactive and individual idiotypes through an analysis of 12 dextran-binding proteins. This correlation has been possible because of the apparent sequence identity of the corresponding lambda chains. Expression of a cross-reactive idiotype was localized to two residues and/or a carbohydrate in the second hypervariable region of the heavy chain. Two individual idiotypes correlate with the two amino acids within the third hypervariable region that comprises the D segment of the dextran-binding proteins. These results demonstrate that idiotype reagents can recognize two amino acid differences within V and D segments of classical variable regions. In anti-dextran antibodies, cross-reactive idiotypes involve V-region determinants, whereas individual idiotype determinants correlate with D-segment variation.
The immune response to the synthetic terpolymer L-glutamic acidS°-L-alaninea°-Ltyrosine 1° (GAT) is controlled by an H-2-1inked immune response gene. In mice bearing the H-2 ~' b, d, f, k haplotypes, GAT stimulates antibody formation and primes for subsequent T cell proliferative responses to GAT in Vitro (1, 2). GAT does not stimulate antibody production or prime for T cell-proliferative responses in mice bearing nonresponder, H-2 p'q'a, haplotypes. Nevertheless, nonresponder mice can develop GAT-specific antibody and T cell proliferative responses if immunized with GAT complexed to methylated bovine serum albumin (MBSA) (GAT-MBSA) (1, 2). To date, our studies suggest that the lack of responses to GAT in nonresponder mice is a result of the preferential development of GAT-specific suppressor T cells (3).The mechanism(s) by which GAT-specific suppressor T cells regulate immunity have been investigated by analysis of T cell extracts from GAT-primed nonresponder mice (4-7). These extracts contain a GAT-specific soluble T cell suppressor factor(s) (GAT-TsF) that mimics the effects of suppressor T cells by inhibiting development of GAT-specific plaque-forming cell (PFC) responses stimulated by GAT-MBSA in nonresponder mice in vivo and in vitro. Recent experiments demonstrated that extracts that contain GAT-TsF also inhibit GAT-specific proliferative responses by T cells from GAT-MBSA-primed, nonresponder mice. The materials in the extracts that inhibit PFC and proliferative responses appear to copurify (8). These data suggest that a single mediator, or closely related set of mediators, can inhibit both GATspecific responses.Experiments described in this communication characterize a monoclonal, GATspecific suppressor factor produced by a hybrid T cell line derived by fusing the HATsensitive AKR thymoma, BW5147, with splenic T cells from GAT-primed nonresponder DBA/1 (H-2 q) mice. This hybrid T cell line produces a factor that is representative of the specific suppressive material extracted from nonresponder T
Studies on the origin, identification, and characterization of osteoclasts have been difficult. This is in part due to a lack of definitive osteoclast markers and the similarity of these cells in form and function to cells of the mononuclear phagocyte system. To solve this problem, we inoculated isolated chick osteoclasts into mice to generate osteoclast-specific monoclonal antibodies. Supernatants from growth-positive hybridomas were screened by indirect immunofluorescent methods against cultured osteoclasts, monocyte-derived multinucleated giant cells, cultured monocytes, fibroblasts, and limb mesenchyme. Select hybridomas were cloned to produce 375 clones, which were analyzed as described above. Antibody from select clones was also reacted with paraffin sections of bone. In addition, two clones have been analyzed by enzyme-linked immunosorbent asssay (ELISA) and Western blot analysis. Antibody binding from an osteoclast-specific clone and a clone reactive with osteoclasts, giant cells, and cultured monocytes (as determined by immunohistochemical assay) was confirmed by antibody-binding and titration curves quantitated by ELISA. The above studies demonstrate that osteoclast specific antigens exist, and that osteoclasts, giant cells, and cultured monocytes share common determinants not found on other cells screened.The multinucleated osteoclast serves as the major cell type responsible for degradation of bone matrix, and its importance in bone growth, skeletal remodeling, and electrolyte homeostasis has been well established (1-3). The mechanisms and regulation of osteoclast-mediated bone resorption are not yet clearly understood; moreover, little is known about the recruitment and differentiation of osteoclast precursors (4, 5). It is generally believed that osteoclasts originate from cells belonging to the mononuclear phagocyte system (6-8). Although different, macrophages and osteoclasts share certain similarities in form and function, including membrane folding (9), positive acid phosphatase staining, activity of other lysosomal enzymes, and the ability to degrade connective tissue (2, 10). Chick-quail chimera studies (l l, 12) have demonstrated a blood-borne origin for the osteoclast, and parabiosis and marrow transplantation have been successfully used to correct the osteoclast defect in osteopetrosis (13,14). Together, these observations support the hypothesis that osteoclasts are polykaryons that derive from circulating mononuclear cells belonging to the monocyte-macrophage family.In various cell populations, a seemingly homogeneous phenotype can now be divided into functional subpopulations with monoclonal antibodies raised to unique cell surface components. In this regard, mononuclear phagocytes have been shown to play important roles as antigen-presenting cells (15), cytotoxic effector cells (16), and also as secretory cells 1592 (17). Recently, it has been demonstrated by the use of monoclonal antibody technology that one cell type may not be responsible for all functions. In this context, ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.