Monoclonal rat anti-major histocompatibility complex antibodies display specificity for rat, mouse, and human target cells.

24 monoclonal rat antibodies are described that are reactive with determinants encoded by the major histocompatibility complex (MHC) of the rat. These hybridoma antibodies were derived by fusing mutant mouse myeloma cells to spleen cells from Lewis rats immunized with allogeneic Brown Norway cells. All 24 antibodies are cytotoxic for both Brown Norway target cells and target cells from the appropriate MHC congenic rats. Pattern of cytotoxicity and hemagglutination strongly suggest reactivity against class I (K or D equivalent) rat MHC determinants. Cytotoxic cross-reactivity patterns were generated for each monoclonal antibody on a panel of rat and mouse lymphoid cells and human peripheral T lymphocytes. A high degree of interspecies cross-reactivity was noted with approximately one-half of the antibodies positive on human and/or mouse target cells. 11 antibodies recognized polymorphic determinants in the mouse, and, by using target cells from MHC congenic mouse strains, it was shown that these determinants are encoded by genes within the H-2 complex. Finally, by considering the overall reactivity patterns of these monclonal antibodies on all target cells, one can show that these 24 antibodies represent a minimum of 14 antibody specificities.

Morphologic and Genetic Verification That Monterey Botryllus and Woods Hole Botryllus are the Same Species.

To determine whether Monterey Botryllus and Woods Hole Botryllus are the same species, comparisons were made of their morphology, biology, and colony specificity. In addition, matings were carried out to ascertain whether fertile [Monterey x Woods Hole] F1 progeny could be obtained. The morphology and biology of Botryllus colonies from Monterey and from Woods Hole are very similar, and fertile F1 progeny were obtained from interpopulation crosses. Therefore, we conclude that Monterey and Woods Hole Botryllus belong to the same species. However, slight differences were observed in the allorecognition reactions (colony specificity) of these two populations. Although there are some inconsistencies among the descriptions of Botryllus schlosseri and further extensive studies of Botryllus taxonomy are needed, our data indicate that Botryllus from Monterey and from Woods Hole may be designated contingently as B. schlosseri.

Direct evidence for a protein recognized by a monoclonal antibody against oxidatively modified LDL in atherosclerotic lesions from a Watanabe heritable hyperlipidemic rabbit.

Low density lipoproteins (LDL) that have been oxidatively modified have been implicated in the pathogenesis of atherosclerosis. Monoclonal antibodies were generated against oxidatively modified human low density lipoproteins (OxLDL); these antibodies reacted with OxLDL, but did not react with native LDL, either in an enzyme-linked immunosorbent assay (ELISA) or a Western blot analysis. The anti-OxLDL antibodies did react with other modified forms of LDL (eg, acetylated LDL, malondialdehyde-modified LDL, and cell-modified LDL) that were recognized by the scavenger receptor on macrophages. Single- and double-label immunofluorescence of atheromatous lesions from a Watanabe heritable hyperlipidemic (WHHL) rabbit demonstrated some colocalization of proteins detected by anti-LDL and anti-OxLDL antibodies. However, clearly there were also areas stained by the anti-OxLDL antibodies that did not stain with anti-LDL. Staining of the lesion by the anti-OxLDL antibody was abolished by adsorption of the antibody with OxLDL, but not by adsorption with LDL or bovine serum albumin. Arterial tissue from a control New Zealand White rabbit did not show staining with anti-LDL or anti-OxLDL antibodies. These observations suggest that OxLDL (or possibly other proteins recognized by the anti-OxLDL antibody) is present in atheromatous lesions of WHHL rabbits, and are consistent with oxidatively modified lipoproteins having a role in atherogenesis.

Human atherosclerosis. III. Immunocytochemical analysis of the cell composition of lesions of young adults.

There have been only limited immunocytochemical studies of the cell composition of the early lesions of human atherosclerosis, and none that incorporate a comprehensive panel of antibodies to various cell types and subsets. The authors thus performed a prospective study of 27 lesions from 16 different individuals ranging in age from 15 to 34 years. These were all lesions that appeared grossly as slightly raised, yellow fatty streaks in the posterior ascending aorta, but on histologic examination had varying degrees of round-cell, spindle-cell, and foam-cell accumulation. Using a panel of antibodies, including monoclonal antibodies specific for smooth muscle cells [HHF35], human macrophages [HAM56], endothelial cells [monoclonal antibodies to F. VIII related antigen], lymphocytes [anti-CD45, anti-CD20, anti-CD45RO, anti-T-cell receptor], it was revealed that the predominant cell type in these early lesions was the smooth muscle cell, including the vast majority of the foam cells, which tended to appear in the deeper regions of the lesions. There were variable numbers of smooth muscle cells and lymphocytes; the latter were exclusively T cells. It is concluded that in atherosclerotic lesions of young adults, which may represent various stages of fatty streak formation and advanced fatty streaks, smooth muscle cell accumulation may be an early event.

Smooth muscle cells can express cytokeratins of "simple" epithelium. Immunocytochemical and biochemical studies in vitro and in vivo.

Cytokeratins are a set of 19 proteins that together constitute the class of intermediate filament protein expressed by epithelial cells and tumors. Using a panel of 9 different monoclonal anti-cytokeratin antibodies, the authors have performed immunocytochemistry on methanol-fixed, frozen sections and methacarn-fixed, paraffin-embedded tissue of human myometrial specimens. Anomalous cytokeratin expression (ACE) by smooth muscle cells was found in all specimens. Immunoblots of this tissue confirmed the presence of cytokeratin 19, and possibly 8. In addition, immunocytochemical studies demonstrated ACE in human fetal tissues within the intestinal muscularis and the heart, especially in the region of the aortic outflow tract, and in 8 of 19 cases of leiomyosarcoma from adults. Indirect immunofluorescence studies were also performed on cells explanted from myometrial tissue; the overwhelming majority of cells derived from these cultures were smooth muscle cells as verified by expression of muscle actins, and a subpopulation of these cells was found to be cytokeratin-positive. ACE was confirmed in vitro by double labeling experiments demonstrating simultaneous expression of muscle actins and cytokeratins within the same cell. The significance of this smooth muscle cell ACE is unknown, but it may be a phenotypic marker of smooth muscle in a proliferative state. ACE could be a source of confusion in the immunocytochemical analysis of poorly differentiated malignancies if a complete panel of antibodies is not employed.

Monoclonal rat anti-MHC alloantibodies detect HLA-linked polymorphisms in humans.

Two monoclonal rat anti-MHC alloantibodies detect a polymorphic determinant expressed on the peripheral lymphocytes of normal human donors. The pattern of cytotoxicity observed with these antibodies correlated with the HLA type of the individual; no HLA-A-locus specificities showed significant associations, and all of the HLA-B-locus specificities showing significant association were members of the Bw6 supertype. Family studies established that the determinant detected by the monoclonal antibodies is linked to HLA. These studies therefore provide an alternative basis for the production of monoclonal antibodies to polymorphic HLA determinants based on the conservation of polymorphic MHC determinants between man and rats.