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Results for “HLA-B44 Antigen”

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At least 19 recordsLinked to original sources
PubMed1992

Differentiation of class I- and class II-directed donor-specific alloreactivity in bronchoalveolar lavage lymphocytes from lung transplant recipients.

Previous studies have demonstrated that donor antigen-specific primed-lymphocyte-test (PLT) reactivity of bronchoalveolar lavage lymphocytes is strongly associated with acute pulmonary rejection and with obliterative bronchiolitis (OB); however, a systematic analysis of PLT reactivity as being class I-or II-directed has not been performed. To assess reactivity directed against individual class I or II antigens, we tested a total of 67 BAL-derived lymphocyte samples from 26 recipients for alloreactivity in the PLT, using a pool of allogeneic cells and selected homozygous typing cells (HTCs) representing the HLA class I and II antigens expressed by the recipient and donor cells. The results obtained by PLT were correlated with the clinical status of the recipient with regard to rejection, infection, and OB. In 9 of 10 cases where transbronchial biopsy results were consistent with rejection, donor antigen-specific allogeneic PLT reactivity was observed and, more specifically, could be determined to be directed toward donor class II antigen in 8 of these cases. For 3 of 4 recipients tested chronologically, positive donor antigen-specific PLT reactivity was observed at the time of and 2-3 1/2 months prior to the diagnosis of rejection by transbronchial biopsy. During periods of acute infection, donor antigen-specific PLT reactivity was not observed; instead, non-specific PLT reactivity of BAL-derived cells (i.e., reactivity that did not correlate with any defined HLA antigens) was observed as well as reactivity associated with the self-antigens expressed by the recipients' cells. The PLT reactivity of BAL-derived cells from a recipient diagnosed with OB correlated specifically with one of the disparate donor class I antigens (HLA-B44). In 23 cases, BAL cells were propagated in the presence of autologous cells and rIL-2, thereby allowing for sufficient numbers of cells to test with a panel of 29 HTCs and to analyze for cell surface phenotype. The cultured BAL cells from 4 recipients undergoing a rejection episode demonstrated a predominant CD4+ phenotype consistent with the class II-directed reactivity observed in PLT. However, these results did not demonstrate a phenotype distinctive from the 7 BAL results obtained from 4 quiescent recipients. In marked contrast, the cultured BAL cells obtained from 4 recipients diagnosed with OB demonstrated a predominant CD8+ phenotype, with 60-92% of the cultured cells being CD8+. These results are consistent with the class I-directed reactivity observed in PLT.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Molecular and endocrine characterization of a mutation involving a recombination between the steroid 21-hydroxylase functional gene and pseudogene.

The gene encoding steroid 21-hydroxylase activity, P450c21B, is located in the major histocompatibility complex (MHC) class III region, in close proximity to a highly homologous pseudogene, P450c21A. Recombinations between P450c21B and P450c21A have been shown to result in deficiency of 21-hydroxylase activity, the usual cause of congenital adrenal hyperplasia (CAH). A mutant P450c21 gene from a patient with simple virilizing CAH was identified and shown to be consistent with a recombination between P450c21A and P450c21B. Sequence analysis of the mutant gene showed the recombination site to be located between the first exon and the second intron. The mutant gene encodes a leucine instead of the normal proline at codon 31. This mutation resides on a chromosome bearing the HLA-B44 serotype. A comparison of mutations associated with HLA-B44 and that normally found with the HLA-Bw47 serotype suggests that the HLA-B44 mutations are of more ancient origin. The patient's homologous chromosome has a deletion of P450c21B. Endocrinological testing therefore allows for testing of the mutant gene in genetic isolation. Such testing demonstrated that the patient was capable of producing aldosterone and retaining sodium in response to a low-sodium diet, indicating that the mutant gene encodes an enzyme with partial 21-hydroxylase activity.

Adrenal Hyperplasia, Congenital↗
PubMed1992

A cytotoxic monoclonal human hybridoma antibody (TrJ3) against HLA-B44(12) and -B45(12).

We have generated a human monoclonal cytotoxic IgM lambda antibody (TrJ3) that reacted specifically with all lymphoblastoid B-cell lines expressing HLA-B44(12) and B45(12). TrJ3 hybridoma supernatant was suitable for HLA-B12 typing of freshly isolated blood mononuclear cells. Analysis of available amino acid sequences of HLA-B molecules indicated that the alpha 1 domain does not contain the TrJ3 serological epitope. Since HLA-B44 is associated with a unique serine residue at position 167 that points towards the peptide binding groove, we propose that S167 of the alpha 2 domain helix is a critical part of the TrJ3 epitope.

Amino Acid Sequence↗
PubMed1991

Human leucocyte antigens and tardive dyskinesia.

HLA status was assessed in matched groups of schizophrenics, 20 with and 20 without tardive dyskinesia. The antigen frequencies were also compared with that in a control sample. The anticipated excess of HLA-B44 was not confirmed. Pooled data displayed a shortfall of HLA-Cw7 and an excess of HLA-B44 in schizophrenics relative to population controls.

Adult↗
PubMed1991

Expression of a liver fatty acid binding protein/human decay-accelerating factor/HLA-B44 chimeric gene in transgenic mice.

The intestinal epithelium is characterized by the rapid and continuous renewal of its four principal cell types and by its ability to establish and maintain remarkably complex spatial differentiation along its crypt-to-villus and duodenal-to-colonic axes. We have previously used transgenic mice containing liver fatty acid binding protein/human growth hormone (L-FABP/hGH) fusion genes to analyze the molecular mechanisms responsible for encoding positional information in this epithelium. Because these studies could not distinguish whether cis-acting sequences in the L-FABP promoter or hGH structural gene were responsible for the observed cellular and regional patterns of transgene transcription in the gut, a second model fusion gene has now been constructed. It consists of nucleotides -596 to +21 of rat L-FABP linked to a cDNA encoding a chimeric protein, human decay-accelerating factor (DAF, minus the site of attachment of its COOH-terminal glycophospholipid anchor), coupled to the transmembrane (TM) and cytoplasmic domains of human HLA-B44. RNA blot hybridization and immunocytochemical analyses revealed that the cell-specific and region-specific expressions of DAF-TM and hGH in adult mice appear identical along both axes of the gut, indicating that cis-acting elements contained within the 5' nontranscribed region of the L-FABP gene rather than in the reporter are largely responsible for these observed patterns of transgene expression. Unlike pre-hGH, a prototypical secreted protein, DAF-TM is a membrane protein. The ability to direct its expression along the length of both axes of the gut provides an opportunity to analyze in vivo the sorting pathways of membrane-associated proteins in normal epithelial cells as a function of their location and differentiation. Light microscopic studies indicate that DAF-TM is targeted to the basolateral and apical surfaces of villus-associated enterocytes.

Amino Acid Sequence↗
PubMed1991

Attempts to optimize active specific immunotherapy for melanoma.

During the past 5 years, we have been conducting clinical trials with a therapeutic melanoma vaccine (melanoma "theraccine"). Mechanical lysates of two melanoma cell lines chosen for their complementary characteristics were combined with the adjuvant DETOX and injected subcutaneously on weeks 1, 2, 3, 4 and 6 for one or two courses, and then monthly in patients with objective clinical responses. Of 109 patients, 22 (20%) have had objective clinical regression of tumor masses, with 5% complete responses. Ten patients have lived more than a year. Eight of the 10 are still alive, five of whom have lived more than 3 years. It was not necessary to achieve complete remissions to cause an increase in survival, and most of the long-surviving patients have one or more (stable) residual nodules. The pace of the disease process has clearly been slowed in those individuals. A rise in the level of cytotoxic T lymphocyte precursors in the blood (pCTL) has correlated with clinical response. Only one patient without such a rise in pCTL has had a response, and assays in that patient were considered unreliable. Both CD4+ and CD8+ CTL have been cloned from the blood of immunized patients. Both types of CTL killed a number of melanoma cell lines, but not other types of tumor or normal cells (lymphoblasts and melanocytes). CD8+ CTL have not been restricted to killing the autologous melanoma. MHC restriction by the HLA-A2 locus was identified. CD4+ CTL were not restricted only by Class II HLA antigens. Many CD4+ clones killed HLA Class II-negative melanomas, and we were able to block cytotoxicity of a particular clone with either anti-HLA Class I or anti-Class II MHC monoclonal antibodies, or both. An association of clinical response to the theraccine with certain HLA phenotypes, notably HLA-C3, -A2 (and the cross-reactive HLA-A28), B12 (and the related alleles (HLA-B44 and -B45) and perhaps DR4, particularly when combinations of those alleles were present, was suggested by our analysis of 70 patients. It is possible that this simply indicates the sharing of MHC antigens between the immunizing melanomas and the patient's melanoma. However, these MHC molecules may be important in their own right in presenting melanoma-associated antigens in CTL in vivo. Subtractive hybridization of mRNA from lung squamous carcinoma cells from cDNA of the M-1 melanoma cell line has yielded several DNA sequences unique to melanoma. Those are now being analyzed for possible immunogenicity, with cytotoxicity by CTL from immunized patients as the major criterion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adjuvants, Immunologic↗
PubMed1992

Effects of C4 null alleles and homoduplications on quantitative expression of C4A and C4B.

The availability of MoAbs now allows the accurate quantification of the individual C4 isotypes, C4A and C4B. Using a sensitive two-site immunoradiometric technique to measure serum levels of C4A and C4B, we studied the relationship between genotype and phenotype and physiological factors affecting C4 expression in 129 fully genotyped healthy subjects. Our results confirm that there is extensive phenotypic overlap between genotypic groups and it was not possible to determine the presence of single null alleles from total serum C4. Of the factors which may influence C4 expression, we found that age contributes a very small influence but that gender has no effect and there was no evidence for the presence of feedback of null alleles on the expression of remaining genes. Potential problems in quantifying C4 arising from the complex relationship between isotypic identity and serotypic recognition were highlighted by the finding of reversed antigenic expression of a C4B*5 molecule which was recognized as C4A by the anti-Rg:1 monoclonal used in these studies. We also confirmed that the extended MHC haplotype associated with Felty's syndrome, HLA-B44, C4A*3, C4BQ*O, HLA-DR4, encodes an expressed, duplicated, C4A gene.

Adult↗
PubMed1991

Expression of Epstein-Barr virus nuclear antigens in anti-IgM-stimulated B cells following recombinant vaccinia infection and their recognition by human cytotoxic T cells.

Cytotoxic T lymphocytes (CTL) recognizing Epstein-Barr virus (EBV) nuclear antigens (EBNA) are an important host defence mechanism in restricting the proliferation of EBV-infected B cells. Previously, B-type lymphoblastoid cell lines (LCL) infected with vaccinia recombinants encoding for the EBNA proteins have been used to identify A-type-specific CTL epitopes. However, to localize the CTL epitopes encoded by both A- and B-type transformants, B-type LCL are an inappropriate host for vaccinia. In the present study, an alternative host cell for vaccinia infection is described. Initial studies demonstrated that anti-IgM (mu-chain specific)-stimulated human B cells allowed vaccinia virus to replicate more efficiently than either phytohaemagglutinin-stimulated lymphocytes (PHA blasts) or CTL and expressed EBNA proteins following recombinant vaccinia infection. Furthermore, the presentation and recognition of target epitopes expressed on vaccinia-infected anti-mu-stimulated B cell blasts were comparable to that on similarly infected LCL. Anti-mu-stimulated B cells were used to define the CTL epitopes recognized by a panel of CTL clones from an EBV-immune donor. Using recombinant vaccinia-infected anti-mu-stimulated B cells, the CTL response from this donor was mapped to the EBNA6 protein. Most importantly, in vitro stimulation of unfractionated mononuclear cells with vaccinia-infected anti-mu B cells activated a memory CTL response. Based on the vaccinia results, screening of peptides from EBNA6 localized the epitope for the majority of the EBNA6-specific CTL clones to the sequence EENLLDFVRFM, apparently in association with HLA-B44. This work clearly demonstrates that anti-mu-stimulated B cells not only provide an efficient model for localizing the CTL epitope(s) but also raises the possibility of reactivating a memory T-cell response to any gene product expressed by recombinant vaccinia.

Antigens, Viral↗
PubMed1992

Mapping of epitopes, glycosylation sites, and complement regulatory domains in human decay accelerating factor.

Decay accelerating factor (DAF, CD55) is a glycophospholipid-anchored membrane protein that protects cells from complement-mediated damage by inhibiting the formation and accelerating the decay of C3/C5 convertases. DAF deletion mutants lacking each of the four short consensus repeats (SCR) or the serine/threonine-rich region (S/T) were created by site-directed mutagenesis. These deletion mutants were expressed by stable transfection in Chinese hamster ovary cells for the purpose of mapping important structural and functional sites in DAF. The epitopes on DAF for 16 murine mAb were mapped by immunoprecipitation studies as follows: SCR1, 6; SCR2, 3; SCR3, 3; SCR4, 3; S/T, 1. Testing of 13 mAb showed complete blocking of DAF function only by 1C6 and 1H4, both directed at SCR3. The single N-linked glycosylation site was confirmed at a location between SCR1 and SCR2, and the multiple O-linked oligosaccharides were localized to the S/T region. Functional activity of DAF mutants was assessed by the ability of these transfected constructs to protect Chinese hamster ovary cells from cytotoxicity induced by rabbit antibody plus human complement. Removal of SCR1 had no effect on DAF function, but individual deletion of SCR2, SCR3, or SCR4 totally abolished DAF function. Surprisingly, deletion of the S/T region totally abrogated DAF function, but this could be restored by a fusion construct placing the four SCR domains of DAF onto the HLA-B44 molecule, implying that the O-glycosylated S/T region serves as an important but nonspecific spacer projecting the DAF functional domains above the plasma membrane. Overall, the creation of DAF deletion mutants has elucidated important structure-function relations in the DAF molecule.

Animals↗
PubMed1991

Phospholipid-anchored and transmembrane versions of either decay-accelerating factor or membrane cofactor protein show equal efficiency in protection from complement-mediated cell damage.

Decay-accelerating factor (DAF) is a glycosyl-phosphatidylinositol (GPI)-anchored membrane protein that protects cells from complement-mediated damage by regulation of the C3 convertase. To investigate the role of the GPI anchor in the function of DAF, the cDNA encoding human DAF was expressed by transfection in Chinese hamster ovary (CHO) cells. Testing of these DAF transfectants in an antibody plus human complement-mediated cytotoxicity assay demonstrated that DAF protects these cells from cytotoxicity, and that the level of protection increases with expression of surface DAF. A cDNA construct encoding a transmembrane version of DAF (DAF-TM) protects CHO transfectants from cytotoxicity with equal efficiency to DAF. This DAF-TM construct used the TM and cytoplasmic domains of membrane cofactor protein (MCP); an alternate TM version of DAF constructed with the TM and cytoplasmic domains of HLA-B44 showed equivalent protection. The protection from cytotoxicity involved a decrease in the deposition of C3 on the cell, consistent with the effect of DAF on the C3 convertase. A second pair of anchor variants, MCP and a GPI-anchored construct, MCP-PI, were also equivalent in their complement protection. The equivalent function of GPI-anchored and TM versions of a protein was not expected based on the hypothesized increased lateral mobility of GPI-anchored proteins, which should confer a functional advantage in contacting ligand, in this case, C3b or C4b, on the cell surface. These data suggest either that GPI-anchored and TM versions of a protein have equal lateral mobility in the membrane, or else that increased lateral mobility is not advantageous to DAF or MCP in carrying out their complement inhibitory roles. Furthermore, DAF and MCP demonstrated approximately equal protection of cells from complement-mediated cytotoxicity, suggesting that DAF and MCP provide overlapping levels of protection to cells against damage mediated by the complement system.

Animals↗
PubMed1991

Association of polymorphisms in the HLA-B region with extended haplotypes.

Genomic probes from the HLA-B region of the major histocompatibility complex (MHC) were used to study the association of restriction fragment length polymorphisms (RFLPs) with various MHC alleles, complotypes, and extended haplotypes. The two DNA probes, M20A and R5A, were derived from previously cloned cosmids and are located 38 and 110 kilobases (kb) centromeric to HLA-B, respectively. Five different RFLP variants occurring in five different haplotypic combinations were detected within a panel of 40 homozygous-typing cells and cells from 21 families using Bst EII. In two informative families with HLA-B/DR recombinations the inheritance of the RFLP variants was consistent with their mapping between HLA-B and complotypes. The R5A/M20A haplotypic pattern 6.5 kb/3.0 kb (A) had a normal Caucasian frequency of approximately 0.43 and was found in all independent examples of the extended haplotypes [HLA-B8,SC01,DR3], [HLA-B18,F1C30,DR3], [HLA-Bw62,SC33,DR4], [HLA-B44,SC30,DR4], and [HLA-Bw47,FC91,0,DR7]. The patterns 6.9 kb/3.0 kb (B), 6.5 kb/4.7 kb (C), 1.45 kb/3.0 kb (D), and 6.9 kb/4.7 kb (E) had normal Caucasian frequencies of approximately 0.23, 0.15, 0.15, and 0.04 and were found on all independent examples of [HLA-B38,SC21,DR4], [HLA-Bw57,SC61,DR7], [HLA-B7,SC31,DR2], and [HLA-B44,FC31,DR7], respectively. Individual complotypes or HLA-B alleles which were markers of extended haplotypes showed variable associations. For example, HLA-B7 and the complotype SC31 were associated with all R5A/M20A RFLP haplotypes except haplotype E, although [HLA-B7,SC31,DR7] was associated exclusively with haplotype D. HLA-B27, not known to be part of an extended haplotype, was surprisingly exclusively associated with the 6.5 kb/4.7 kb or C haplotypic pattern in all five instances tested. These findings support the concept of regional conservation of DNA on independent examples of extended haplotypes. The results also further characterize these haplotypes.

Alleles↗
PubMed1991

Novel detection of restriction fragment length polymorphisms in the human major histocompatibility complex.

Cosmid genomic DNA clones have been used as hybridization probes in genomic Southern blot analysis to define restriction fragment length polymorphisms (RFLPs) in the major histocompatibility complex (MHC). Using 14 different enzymes and three overlapping cosmid clones we have detected six RFLPs in a 100 kilobase (kb) segment of DNA in the class III region extending centromeric of the TNFA gene toward HLA-DR. Four of the five RFLPs, defined using the enzymes Taq I, Rsa I, Hinc II, and Hind III, and detected by the cosmid clone cosM7B, map to a 29 kb segment of DNA that includes all of the recently described G2 (BAT2) gene and a large portion of the 3' end of the G3 (BAT3) gene. The different RFLP variants were established by analyzing the DNA from three informative families and a panel of 51 HLA-homozygous typing cell lines. CosM7B detects Taq I variants of 4.3 kb, and 2.9 kb or 2.8 kb, Rsa I variants of 2.9 kb or 2.4 kb, Hinc II variants of 5.8 kb or 3.8 kb and 1.4 kb, and a Hind III variant of 4.8 kb, while cosOT2 detects Taq I variants of 4.5 kb or 4 kb. The distribution of the Rsa I, Hinc II and Taq I RFLPs detected by cosM7B, and the Taq I RFLP detected with cosOT2, within the panel of cell line DNAs was assessed by Southern blotting. The 4.3 kb Taq I variant was observed in only one cell line with the extended haplotype HLA-A29, C-, B44, SC30, DR4. The other RFLPs, however, occurred much more frequently. The 2.8 kb Taq I variant was observed in 20% of haplotypes, the 2.9 kb Rsa I variant was observed in 42% of haplotypes, and the 5.8 kb Hinc II variant was observed in 12% of haplotypes analyzed. The 4.5 kb Taq I variant detected by the overlapping cosmid cosOT2 was present in 21% of haplotypes. Analysis of the RFLP variants with each other revealed seven different haplotypic combinations. Three of the haplotypic combinations were each subdivided into two subsets on the basis of the Nco I RFLP variant they carried at the TNF-B locus. These haplotypic combinations potentially allow differentiation among different extended haplotypes such as HLA-B8, SC01, DR3, HLA-B18, F1C30, DR3, and HLA-B44, FC31, DR7. The RFLPs detected by the cosmid clones thus provide new tools which will be useful in the further genetic analysis of the MHC class III region.

Alleles↗