Biomedical subjects

R Sackstein

Publications and source records attributed to R Sackstein.

44 records · Page 3Linked to original sources

PubMed1989

Lymphocyte recognition of psoriatic endothelium: evidence for a tissue-specific receptor/ligand interaction.

Epidermotropic lymphocytes are an essential cellular component of the skin-associated lymphoid tissues (SALT). Dermal lymphocytic infiltrates are also characteristics of inflammatory dermatoses, such as psoriasis, and may be involved in the pathogenesis of the disease, although the mechanisms by which lymphocytes are recruited into these sites are not known. We have used an in vitro lymphocyte adherence assay to test the hypothesis that specialized endothelial cells are present in inflamed skin, and are capable of supporting lymphocyte adherence and promoting lymphocyte emigration. In this assay, we assessed the binding of lymphocytes overlaid onto frozen sections of normal and psoriatic skin. Peripheral blood mononuclear cells (PBMC) from patients, from healthy volunteers, and from rat thoracic duct bound specifically to dermal endothelia in psoriatic plaques, in steroid-resistant areas of plaques, but not in uninvolved skin or skin from healthy individuals. Analysis of the binding properties of lymphocyte subsets revealed preferential adherence by CD4+ T cells as compared with CD8+ T cells and to B cells. Interestingly, PBMC from patients undergoing ultraviolet light therapy failed to adhere to autologous skin or to lesion-containing skin sections from untreated patients. Additional studies indicate that the lymphocyte-endothelial interaction is an energy- and calcium-dependent process and involves surface glycoprotein and carbohydrate moieties, requirements similar to those found in specific lymphocyte interactions with high endothelial venules in lymph nodes during the homing process. Pretreatment of lymphocytes with antibodies directed against homing receptors mediating migration into lymph nodes and into gut-associated lymphoid tissues, however, did not interfere with lymphocyte adherence to psoriatic endothelium. In contrast, anti-lymphocyte function associated antigen (LFA)-1 antibody partially inhibited lymphocyte binding to chronic plaques. We conclude that a tissue-specific receptor/ligand interaction independent of LFA-1 directs lymphocyte emigration from the dermal microvasculature into the psoriatic dermis and that LFA-1 plays only an accessory role in the adhesion process.

Animals↗

PubMed1988

Lymphocyte adhesion to psoriatic dermal endothelium is mediated by a tissue-specific receptor/ligand interaction.

Dermal lymphocytic infiltrates are characteristic of psoriasis and may be involved in the pathogenesis of the disease. We have utilized an in vitro lymphocyte adherence assay to examine the mechanism(s) mediating lymphocyte migration into psoriatic skin. In this assay, we assessed the binding of lymphocytes overlaid onto frozen biopsy sections of normal and psoriatic skin. Lymphocytes isolated from human blood and rat thoracic duct bound specifically to dermal endothelia in psoriatic plaques but not to those of uninvolved skin from psoriatic patients or skin from normal individuals; analysis of the binding properties of B cells and T lymphocyte subsets revealed a preferential binding of CD4+ T cells compared with CD8+ T cells or B cells. This lymphocyte-endothelial interaction is an energy- and calcium-dependent process and involves surface protein and carbohydrate moieties, requirements similar to those found in lymphocyte interaction with post-capillary high endothelial venules (HEV) in lymphoid tissues. However, preincubation of lymphocytes with antibodies directed against surface molecules mediating adhesion to HEV of peripheral lymph node and gut-associated lymphoid tissue did not interfere with the capacity of lymphophocytes to bind to the skin. The results of this study support the hypothesis that emigration of lymphocytes from vasculature into psoriatic skin is promoted by the presence of specialized endothelia in psoriatic dermis capable of mediating specific lymphocyte-endothelial interactions.

Adult↗

PubMed1985

Molecular biology of the human and mouse MHC class III genes: phylogenetic conservation, genetics and regulation of expression.

The generation of complementary and genomic DNA clones for the human and mouse MHC class III genes has advanced the study of the organization, structure, genetics and expression of these loci. These clones have been useful in defining new polymorphic markers in each species and therefore permit a more complete genetic analysis of the complement cluster and the MHC as a whole. The coding sequences of the factor B and C4 genes are extensively conserved both within and between species, in contrast to the coding sequences of other MHC products. In human and mouse, the organization of the class III genes is similar with respect to order and position between the class II and class I regions of the MHC. However, these inter-species similarities in the organization and products of the class III genes does not extend to their regulation. In addition to complement gene expression being regulated differently between tissue sites within a species, expression is apparently regulated differently in analogous tissues between species. The considerable progress which has been made in the molecular analysis of C2, factor B and C4 using DNA clones forms the basis for the future study of the biology of the class III genes and the role of complement in inflammatory processes and in the immune system.

Animals↗

PubMed1984

Subdivision of the S region of the mouse major histocompatibility complex by identification of genomic polymorphisms of the class III genes.

The S region of the mouse major histocompatibility complex (MHC) encodes the class III proteins, the second (C2) and fourth (C4) components of complement, and factor B. Previously, the assignment of S-region haplotypes was based on analysis of protein polymorphisms. The recent availability of C2, C4, and factor B cDNA probes prompted a search for restriction fragment length polymorphisms which would serve as additional genetic markers for these loci. DNA was isolated from livers of mice of all standard inbred H-2 haplotypes and of haplotypes pz and bs. These DNA samples were digested with restriction endonucleases and analyzed by Southern blot. By the pattern of restriction fragment length polymorphism observed, specific markers have been identified in factor B of haplotypes f, u, z, bs, r, and v, and in C4 of haplotypes b,q,f,j,p,s,pz,r, and v. These genetic markers were used in the analysis of S-region composition in strains B10.TFR5(H-2ap5) and C3H.LG(H-2dx), and a possible intra-S-region recombinant was revealed in the H-2dx haplotype. The genetic markers identified here subdivide the S region and will be of value in defining further the composition of the complement gene complex of the mouse MHC.

Alleles↗

PubMed1984

Expression of hemolytically active murine fourth component of complement in transfected L cells.

The S region of the murine major histocompatibility complex contains two related genes (C4-X and C4-Y), one of which encodes the fourth component of complement (C4). We have introduced cloned C4-X and C4-Y genes into L cells. C4-X transfectants contained no detectable C4-related RNA, whereas C4-Y transfectants contained large amounts of C4-related RNA. Culture supernatants of C4-Y transfectants contained processed C4 which was indistinguishable from macrophage-derived C4. The L-cell-derived C4 restored hemolytic activity to C4-deficient serum, served as a substrate for C1s, and underwent autolytic cleavage suggesting the presence of an intramolecular thiolester bond. These experiments identify C4-Y as the functional C4 gene in H-2d mice and indicate that L cells can process pro-C4 correctly.

Amino Acid Sequence↗

PubMed1984

Molecular regulation of MHC class III (C4 and factor B) gene expression in mouse peritoneal macrophages.

To study the molecular regulation of C4 and factor B synthesis in mouse peritoneal macrophages, mouse C4 cDNA clones isolated from an H-2d haplotype liver cDNA library, and a previously described mouse factor B cDNA clone, pBmB2 (9), were used to assess quantitative and qualitative differences in C4 and factor B mRNA in resident and elicited cells. The C4 clones that were isolated, pBmS2 (1 Kb) and pBmS10 (0.9 Kb), overlap and together span a 1.5 Kb coding region of mouse pro-C4, extending from the alpha-chain through the gamma-chain; four nucleotide substitutions are evident in comparing 316 bp of the sequence of clone pBmS10 to that of a previously described mouse C4 clone, pMLC4/w7-2 (23). By using these probes, Northern blot analysis of total cellular RNA revealed similar C4 mRNA levels in resident peritoneal macrophages from high-C4 (B10.A) and low-C4 (C3HeB) strains. Pulse and pulse-chase studies of C4 and factor B synthesis were performed on resident, starch-elicited, and thioglycollate-elicited peritoneal macrophages at two culture time periods, 0 to 9 and 24 to 33 hr, and total cellular RNA was isolated from each population at 4.5 and 28.5 hr of culture for Northern blot analysis of C4 and factor B mRNA content. The data demonstrate that as previously reported, C4 production decreases in elicited compared with resident macrophages and decreases with time in culture; however, factor B synthesis does not differ among resident and elicited cells and it increases with time in culture. The variations in C4 and factor B production by mouse peritoneal macrophages are not associated with alterations in C4 and factor B protein processing, catabolism, or secretion; rather, they are a function of differences in net amounts of C4 and factor B mRNA. These data provide direct evidence that the regulation of expression of these class III MHC genes in mouse peritoneal macrophages is a pretranslational event.

Animals↗

PubMed1983

Phylogenetic conservation of a class III major histocompatibility complex antigen, factor B. Isolation and nucleotide sequencing of mouse factor B cDNA clones.

The complement protein factor B is a novel serine protease which is encoded within the major histocompatibility complex in man, guinea pig, and mouse. To determine the structure of mouse factor B, cDNA clones were isolated from mouse strains of two different major histocompatibility complex haplotypes, H-2k and H-2d, and clones of 0.9 and 1.5 kilobases, respectively, were sequenced. The H-2d clone includes the H-2k clone sequence and spans 94% of the Bb-coding sequence. No differences in sequence or in restriction enzyme sites were observed between the H-2k and H-2d clones. The H-2d clone displays 83% nucleotide homology and 83% (derived) amino acid homology with that of human factor B; there are no insertions or deletions. Comparison of the mouse and human factor B sequence reveals extensive regional homology at the catalytic residues and in the NH2-terminal portion of the Bb fragment.

Amino Acid Sequence↗

PubMedDate not supplied

Specific lymphocyte-endothelial cell interactions regulate migration into lymph nodes, Peyer's patches, and skin.

Lymphocyte migration is a critical component of a functional immune system. It increases the efficiency of the regional immune responses and disseminates locally induced effector cells to distant inflammatory sites. Central to the migratory process is the ability of lymphocytes to extravasate from the blood by selectively binding to segments of venules lined by high endothelium in lymph nodes and mucosal-associated lymphoid tissues. Recent studies have demonstrated that the specific recognition and adhesion of lymphocytes to high endothelial venules (HEV) is mediated by receptor/ligand systems that are different between lymph nodes (LN) and Peyer's patches (PP). The differential expression of lymphocyte surface receptors accounts for the preferential migration patterns of distinct lymphocyte subsets. More recently, the existence of specialized dermal endothelial cells in cutaneous tumors and inflamed skin that are capable of supporting lymphocyte adherence has been documented. This lymphocyte-endothelial cell interaction is an energy- and calcium-dependent process that involves surface glycoprotein and carbohydrates, requirements that are analogous to lymphocyte binding to HEV in LN and PP. Interestingly, antibodies directed against surface molecules mediating adhesion to HEV of LN and HEV of PP have no effect on lymphocyte binding to the dermal endothelium, suggesting that an additional receptor/ligand system promotes lymphocyte traffic into this site. Moreover, similar but additional receptor/ligand interactions may exist and may mediate lymphocyte migration into other sites. The identification and isolation of these receptor/ligand systems will provide important insights into both regional specialization of the normal immune response and pathophysiology of inflammatory diseases in diverse organs and tissues.

Animals↗