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PubMed1997

Induction of major histocompatibility class II antigen on microglial cells in postnatal and adult rats following intraperitoneal injections of lipopolysaccharide.

Microglial cells, notably the ramified form, were induced to express major histocompatibility complex (MHC) class II antigen in postnatal and adult rats given intraperitoneal injections of lipopolysaccharide (LPS). The immunoreactive microglia which occurred in cell colonies or clusters were detected immunohistochemically with the monoclonal antibody OX-6. Some of the widely distributed MHC II positive cells were round or amoeboidic located preferentially in the perivascular area. In view of the widespread occurrence of microglial cells showing OX-6 immunoreactivity which is negligible in normal animals, it is suggested that the effect of LPS on microglia in vivo is a widespread phenomenon and is independent of age. It is suggested that the endotoxin not only triggers off the immunological potentiality of these cells but also elicits the entry of some mononuclear cells into the brain parenchyma.

Aging↗
PubMed1983

Organization of the transcriptional unit of a human class II histocompatibility antigen: HLA-DR heavy chain.

A total of 5724 base pairs of a recombinant phage DNA containing a human HLA-DR heavy chain gene including flanking regions has been analyzed. The regions corresponding to all the exons have been identified. The sites of initiation of transcription and polyadenylation have been determined. A large intron of 2399 base pairs separates the first exon containing the 5' untranslated region and the signal peptide from the second exon containing the N-terminal peptide domain.

Amino Acid Sequence↗
PubMed1985

Implications of the invariant gamma-chain on the intracellular transport of class II histocompatibility antigens.

We have examined the role of the invariant gamma-chain on the intracellular transport of human class II histocompatibility antigens. mRNA was selected by hybridization to cDNA corresponding to class II alpha-, beta-, and gamma-chains, and the obtained mRNA fractions were injected individually and in various combinations into X. laevis oocytes. Translation products were isolated after various periods of chase, and their carbohydrate moieties were analyzed to monitor the subcellular localization of polypeptide chains. A mixture of alpha-, beta-, and gamma-chains, or gamma-chains alone, were transported and glycosylated to the same extent as in a B lymphoblastoid cell line. However, although alpha- and beta-chains formed a complex in the absence of the gamma-chain, the transport of this complex was slowed down. Furthermore, the glycosylation of alpha- and beta-chains appeared incomplete. Thus, the invariant gamma-chain seems to play a crucial role for the rate of transport and glycosylation of class II alpha- and beta-chains.

Animals↗
PubMed1993

Major histocompatibility class II antigen expression on the surface of epidermal cells from normal and ultraviolet B irradiated subjects.

The influence of ultraviolet B irradiation in therapeutic doses on MHC II-positive epidermal cell numbers and their surface MHC II antigen expression was studied quantitatively using light microscopic immunoperoxidase and immunogold electron microscopic techniques. In multiple ultrathin sections through many MHC II-positive epidermal cells from five healthy subjects, prior to ultraviolet exposure, Langerhans cells and indeterminate cells were found to express similar densities of surface MHC II antigens, which were uniformly distributed over the cell surface. The variation in surface MHC II antigen expression on 97 dendritic epidermal cells from one subject was normally distributed. Following a 6-week course of ultraviolet B irradiation, in the same doses as those normally used for the treatment of psoriasis, MHC II-positive epidermal cell numbers were significantly reduced (mean decrease to 51% of the pre-UVB sample; p < 0.001 analysis of variance), but their surface MHC class II antigen density was significantly increased (p < 0.05 analysis of variance). No MHC II-negative Langerhans cells were detected in either the pre- or post-UVB samples.

Adult↗
PubMed1983

Primary structure of human class II histocompatibility antigens 3rd communication. Amino acid sequence comparison between DR and DC subclass antigens derived from a lymphoblastoid B cell line homozygous at the HLA loci (HLA-A3,3; B7,7; Dw2,2; DR2,2: MT1,1; Dc1,1: MB1,1).

Class II histocompatibility antigens from a homozygous human lymphoblastoid B cell line (HLA-A3,3; B7,7; Dw2,2; DR2,2; MT1,1; DC1,1; MB1,1) were isolated by an exclusively chemical procedure. After the separation of the alpha and beta chains the amino acid sequences of the extracellular parts of the DR2 alpha and the DR2 beta chains could be determined, in spite of the heterogeneity of both fractions. Peptides isolated in considerably lower yields indicated at least one more alpha chain and 6 further beta chains. By the investigation of these lower-yield enzymatic fragments, in addition to the DR2 alpha and DR2 beta chains, we can now report on the partial amino acid sequences of a DC alpha chain, a second beta chain of DR type and one beta chain of DC type. Furthermore, the isolation of a characteristic glycopeptide suggests the existence of a second beta chain of DC type. The following class II antigens are therefore identified: DR2 alpha/DR2 beta 1, DR2 alpha/DR2 beta 2, DC1 alpha/DC1 beta 1, DC1 alpha/DC1 beta 2, indicating that each subclass can be subdivided into two antigens because each alpha chain type can associate with at least either beta 1 or beta 2. Further investigations must clarify whether the remaining three beta chains are of the DR, DC, or of a third beta chain type. Amino acid sequence comparisons confirm that the human DR antigens are the equivalent of mouse I-E antigens, while human DC antigens are the equivalent of mouse I-A antigens.

Amino Acid Sequence↗
PubMed2000

[Polymorphism of histocompatibility class II antigens coded with the DRB gene in in familial sarcoidosis in Poland].

Several studies suggested association between some human leukocyte antigen (HLA) alleles and sarcoidosis, but none has been conclusive. To confirm possible association of sarcoidosis with HLA-DRB1, -DRB3,- DRB4, -DRB5 associated alleles HLA-DR genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in 17 polish families with familial sarcoidosis and in 101 healthy controls. The families with sarcoidosis consisted of 31 affected first-degree relatives from 16 families, 2 affected cousins from 1 family and 78 healthy relatives of those patients. We found 3 varieties of familial sarcoidosis: a) in parent and offspring (5 pairs), b) in siblings (10 sib pairs and 1 sib triplet) and in cousins (1 family). Genotyping for HLA-DRB1,-DRB3,-DRB4,-DRB5 revealed an over-representation of HLA-DR5(12) and DRw52 among antigens shared by affected relatives comparing to the control group. A significant increase in the frequency of HLA-DR7 and HLA-DRw53 antigens (p < 0.05) was found in subjects from the control group. Comparing the group of family members (affected and healthy relatives taken together, n = 111) with the control group (n = 101) we found a significant differences in the distribution of HLA-DR2(15), HLA-DR5(12), HLA-DR6, HLA-DR9 and HLA-DRw52. Those antigens were more frequent (p < 0.05) in members from families with sarcoidosis. The frequencies of HLA-DR1, HLA-DR2(16), HLA-DR7 and HLA-DRw53 were significantly higher (p < 0.05) in the control group. Presented results suggest that HLA-DRB alleles contribute to the susceptibility to sarcoidosis in the Polish population.

Case-Control Studies↗
PubMed1987

The modulation of class II histocompatibility antigens and 'activated' macrophage determinant in the spinal cord during the development of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the guinea pig--relevance to the induction of remission?

Cryostat sections of spinal cord of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (CREAE) were stained with monoclonal antibodies recognising a Strain 13-specific Ia epitope, a non-strain-specific Ia antigen and an 'activated' macrophage determinant. It was found that both Ia antigens and the 'activated' macrophage determinant, observed on infiltrating cells within both perivascular and meningeal compartments, appeared to be modulated during the course of CREAE. This correlated with the neurological symptoms of the disease. Blood vessels and 'glial' cells expressed both Ia determinants. 'Glial' cells also expressed the 'activated' macrophage antigen. These antigens were modulated with the course of the disease.

Animals↗
PubMed1984

[Primary structure of human class II histocompatibility antigens (HLA-D). I. Isolation, purification and characterization of the HLA-D alpha/beta chain complex from a homozygous lymphoblastoid B cell line, H2LCL (HLA-A3,3;B7,7;Dw2, 2;DR2,2;MT1,1;DC1,1;MB1,1].

The complex of alpha and beta chains of HLA-D membrane antigens has been isolated from a lymphoblastoid homozygous B cell line, H2LCL (HLA-A3,3; B7,7; Dw2,2; DR2,2; MT1,1; DC1,1; MB1,1), by an exclusively chemical two-step procedure and characterized by electrophoresis as well as isoelectric focusing in polyacrylamide gel. Cells were gained using long term cultivation in large scale, the crude membrane by differential centrifugation. The proteins of the crude membrane were then solubilized in NP-40, pH 5.0. The first purification step for HLA-D antigens consisted in an ion-exchange chromatography on carboxymethyl cellulose using the solubilization buffer. By this procedure the complex of proteins with relative molecular masses of Mr approximately 34 000 and Mr approximately 29 000 was in a high percentage not bound to the carboxymethyl cellulose. The bound fraction contained the HLA-A, -B and -C antigens and a component with Mr approximately 31 000 corresponding to the well known Ii-fraction. The bound proteins could be recovered from the column by a sodium chloride gradient. The proteins not bound to the carboxymethyl cellulose were precipitated with acetone, dissolved, dialysed against SDS buffer, pH 7.2 and then submitted to the second purification step, the Sephacryl S-300 chromatography. By this procedure the corresponding complex could be further separated from higher and lower molecular proteins. The complex was used as the starting material for the separation of alpha and beta chains. Amino-acid sequences established of the isolated chains have already been communicated.

Amino Acid Sequence↗
PubMed1984

[Primary structure of human class II histocompatibility antigens (HLA-D). II. Separation of alpha from beta-chains of HLA-D from a homozygous lymphoblastoid B cell line, H2LCL (HLA-A3,3;B7,7;Dw2,2;MT1,1;DC1,1;MB1,1), and characterization of the isolated chain].

In a previous communication we described the preparation of the alpha/beta-chain complex of HLA-D membrane antigens from a homozygous lymphoblastoid B cell line, H2LCL (HLA-A3,3; B7,7; Dw2,2; DR2,2; MT1,1; DC1,1; MB1,1). In this paper we present the separation of the alpha- and beta-chains in quantitative scale using hydroxylapatite chromatography with a pH 7.15 phosphate buffer, containing sodium dodecyl sulfate. An alternative isolation procedure is electrophoresis, taking advantage of the different isoelectric points of the alpha- and beta-chains. The relative molecular masses, the isoelectric points and the N-terminal sequences are discussed and compared with the results of other investigators. Remarkable is the polymorphism of both the chains, especially the beta-chains. The importance of the previously described three step purification procedure for the preparation of these antigens for sequence studies has been pointed out.

B-Lymphocytes↗
PubMed2000

Relationship between gingival hyperplasia and class II histocompatibility antigens in renal transplant recipients.

Gingival hyperplasia, a well-known side effect of ciclosporin A (CS-A), is much more prominent when CS-A is used in combination with calcium channel blockers, especially dihydropyridines. On the other hand, it is interesting to note that this complication is not observed in all patients using this drug combination. This study was conducted in order to investigate the relationship (if any) between major histocompatibility complex antigens and gingival hyperplasia. Seventy-six renal transplantation patients were evaluated by an experienced dentist for gingival hyperplasia. The patients were then divided into two groups according to the presence (group 1, n = 18) or absence (group 2, n = 58) of gingival hyperplasia. There was no significant difference between the two groups regarding age, sex, transplant age, donor type, antihypertensive and immunosuppressive therapy protocols, and CS-A levels. HLA-DR2 antigen was present in 63% of the patients with gingival hyperplasia and in 34% of the patients without gingival hyperplasia. However, the HLA-DR1 antigen frequencies were found to be 11 and 22% in group 1 and group 2, respectively. In patients receiving nifedipine as an antihypertensive therapy, gingival hyperplasia developed more often than in patients receiving verapamil or diltiazem. As a result, in renal allograft recipients with HLA-DR1 antigen, gingival hyperplasia was seen less frequently than in HLA-DR2-positive patients. It is believed that the presence of these antigens regulates the response of the patients to either CS-A and/or calcium channel blockers.

Adult↗
PubMed1987

Pharmacologic effects on the expression of class II histocompatibility antigen in experimental endotoxin-induced uveitis.

Systemic dexamethasone, cyclosporine A, colchicine, indomethacin, and cobra venom factor were administered to Lewis rats that were then challenged with 100 micrograms of Salmonella typhimurium endotoxin. The effects of these five pharmacologic agents in endotoxin-induced uveitis were studied by analyzing their effects on ocular inflammation and on the expression of class II antigen of the major histocompatibility complex (MHC) on the epithelium of the ciliary body and iris. All the agents used in our study exhibited anti-inflammatory effects but only dexamethasone was able to inhibit significantly the expression of Ia antigen on the uveal epithelium. This demonstrates a dissociation between the inflammation and class II antigen expression and supports our previous data that class II antigen presentation may precede the inflammatory infiltrates. The alteration of ocular inflammation and especially the variation of Ia antigen expression in the uveal tissue may provide insight into the mechanism of action and the success of different pharmacologic agents used in the treatment of uveitis.

Animals↗
PubMed1997

Studies on the interaction of T-cells with major histocompatibility complex class II antigens.

1. Major histocompatibility complex class II antigens have the central role in the immune response of 'presenting' antigenic peptide to CD4+ T-cells. This interaction with a T-cell's receptor may result in activation, but, if recognition occurs without collateral molecular interactions which cause 'co-stimulation', these T-cells will be tolerized. 2. In the light of current interest in muscle cell transplantation, a transformed myoblast, TE671, phenotypically comparable to untransformed cells, transfected to express class II, was studied as a stable model of antigen presentation by muscle cells. These cells failed to activate T-cells but induced tolerance. 3. The DR alpha chain is unusual being the only non-polymorphic classical class II polypeptide, raising the question of its functional contribution. To this end, several single polypeptide constructs were generated with contributions from different class II alpha-chains. On this basis, it was established that DR alpha makes significant contributions to peptide binding and that its alpha 2 domain is also important in T-cell recognition, possibly through CD4 binding. 4. One implication of the lack of polymorphism of DR alpha may be that it has a wider range of pairing partners, possibly including beta chains of different isotypes. To address this, it is planned to use transfectants expressing only a mixed isotype pair to generate T-cell clones in vitro. These reagents would be useful tools to detect whether such mixed pairs exist physiologically. In this paper, the development of a system is described which will allow this question to be addressed.

Antigen Presentation↗
PubMed1990

Immunoprotective effect of a calcium channel blocker on macrophage antigen presentation function, major histocompatability class II antigen expression, and interleukin-1 synthesis after hemorrhage.

Hemorrhage induces a severe suppression of the immune system resulting in increased susceptibility to sepsis. Although studies indicate beneficial effects of calcium channel blockers on cell and organ functions after low-flow conditions, it remains unknown whether such agents have any effects on different immune responses after hemorrhage. To study this, C3H/HeN mice were bled to a mean blood pressure of 35 mm Hg and were maintained for 60 minutes, followed by resuscitation with their own shed blood and adequate fluid. The mice received either the water-soluble calcium channel blocker diltiazem (400 or 2400 micrograms/kg body weight) or saline solution (vehicle). Peritoneal macrophages were obtained by lavage 24 hours later. Antigen presentation was measured by coculturing peritoneal macrophages with the D10.G4.1 helper T-lymphocyte clone. Immune associated antigen (Ia) expression was determined by direct immunofluorescence. Interleukin (IL)-1, 6, and tumor necrosis factor-alpha (TNF) levels in peritoneal macrophage supernatants were measured by use of cytokine-specific cellular assays. Hemorrhage caused a significant decrease in peritoneal macrophage antigen presentation function, Ia expression, and IL-1 and IL-6 synthesis in the vehicle-treated group, whereas TNF levels were increased. However, both doses of diltiazem significantly improved peritoneal macrophage antigen presentation, Ia expression, and IL-1 synthesis. IL-6 synthesis was only increased with high doses of diltiazem, whereas both diltiazem doses decreased TNF production. These results indicate that the calcium channel blocker diltiazem can markedly improve macrophage functions after hemorrhage. The use of diltiazem might offer a new therapeutic modality in the treatment of immunosuppression and in decreasing the susceptibility to sepsis after hemorrhagic shock.

Animals↗