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W R McMaster

Publications and source records attributed to W R McMaster.

53 records · Page 3Linked to original sources
PubMed1987

DNA sequence analysis of the rat RT1.B alpha gene.

The major histocompatibility complex (MHC) of the rat (RT1 complex) encodes two sets of class II molecules referred to as RT1.B and RT1.D. The RT1.B alpha gene was isolated for a Sprague-Dawley (RT1b) rat genomic library using a rat RT1.B alpha chain cDNA as a hybridization probe. The coding and the majority of the intron DNA sequence was determined. The structure of the RT1.B alpha gene is equivalent to that of H-2 and HLA alpha chain genes. Comparison of the nucleotide and predicted amino acid sequences of the RT1.B alpha gene with those of the H-2 and HLA genes revealed a high degree of overall sequence conservation. However, two regions of the first external domain (alpha 1), residues 19-23 and 45-78, exhibit marked sequence variation. Two blocks of conserved nucleotide sequence were identified in the 5' promoter region of the RT1.B alpha gene that have been described in all MHC class II genes sequenced to date. These conserved sequences may be involved in the coordinate regulation of expression of class II genes. The cloned RT1.B alpha gene was efficiently transcribed when transfected to mouse L cells.

Alleles↗
PubMed1986

Differential expression of RT1 class II genes in fibroblast cell lines: recognition by allogeneic and xenogeneic T lymphocytes.

A cosmid (cos a 13.1) containing RT1 class II B alpha and B beta genes was introduced into mouse and rat fibroblast cell lines by transformation. Mouse L cells transformed with cos a 13.1-synthesized cell surface class II molecules that were similar, with respect to apparent molecular weight and binding of xenogeneic- and allogeneic-specific antibodies, to class II molecules on rat B cells. RT1 class II molecules on the surface of mouse L cells were recognized by both allogeneic and xenogeneic T cells. In contrast, rat-2 cells transformed with cos a 13.1 did not synthesize any detectable RT1 class II molecules at the cell surface, and the levels of B alpha and B beta mRNA were generally very low or undetectable. This differential expression of exogenous class II genes was not exclusively due to a trans-acting positive regulatory factor in L cells. Other possible explanations for this difference are discussed.

Animals↗
PubMed1985

DNA sequence analysis of a rat RT1 class II A beta gene.

The rat major histocompatibility complex (RT1) encodes twin sets of class II molecules, each consisting of two polypeptide chains referred to as A alpha and A beta, and E alpha and E beta. A gene encoding the RT1.A beta chain was isolated from a rat genomic library using an HLA-DQ beta chain cDNA as a probe. The nucleotide sequence of the coding regions of this gene was determined. Comparison of this sequence with those of the corresponding genes of mouse (H-2A beta) and human (HLA-DQ beta) revealed that this gene has been highly conserved during evolution, and that some parts of the molecule are more conserved than others. Analysis of the nucleotide sequence encoding the two external domains suggests that the membrane proximal domain has been subject to conservative selection, whereas replacement substitutions have been selected positively at certain residues within the amino terminal domain. The overall organization of the RT1.A beta gene is similar to that of the H-2A beta gene.

Amino Acid Sequence↗
PubMed1985

Isolation and characterization of novel suppressor T cell clones from murine fetal thymus.

Murine fetal thymus from C57BL/6J (B6) and DBA/2J contains a cell population that suppresses CTL responses to alloantigens. This suppressor cell population was found to exist in high frequency in murine fetal thymus at the 14th day of gestation. The activity of this cell in the thymus declined rapidly with increasing time of gestation, and suppressor activity in the thymus was undetectable by the time of birth. On the other hand, suppressor activity could be detected in organ cultures of 14-day fetal thymus even after the organs were cultured for 14 or 21 days. Fetal thymocytes from B6 or DBA/2J mice were grown as long-term lines in interleukin 2 (IL 2)-containing medium. Clones of suppressor cells were derived from long-term cultures by micromanipulation. The clones had an average doubling time of 13 to 16 hr and were dependent on IL 2 for growth. The clones were 10- to 100-fold more efficient in suppressing CTL responses to alloantigens than day 15 fetal thymocytes. Analyses of cell surface molecules with the use of monoclonal antibodies and conventional anti-H-2 sera by radioactive binding assays showed that cloned suppressor cells from B6 fetal thymus were Thy-1 and Lyt-2+, and expressed little or no L3T4, Lyt-1, H-2K, H-2D, and class II molecules. The suppressor clones lacked the cytolytic activity of conventional CTL and also served as very poor target cells in CTL-mediated cytolysis. The suppressor function of the cloned cells was radiation-resistant, and this suppression could not be reversed by the addition of excess exogenous IL 2. The cloned cells suppressed CTL responses only when they were added within the first 48 hr of a 5-day culture period. Analyses of the antigen specificity of the suppressor cells showed that they suppressed CTL responses in a nonantigen-specific manner.

Animals↗
PubMed1985

Complete structure of a rat RT1 E beta chain: extensive conservation of MHC class II beta chains.

The rat major histocompatibility complex (RT1 complex) encodes two sets of class II molecules, A alpha A beta and E alpha E beta. A cDNA clone encoding a RT1 E beta chain was isolated from a cDNA library prepared from Wistar (RT1 mu) spleen poly(A) RNA by screening with DNA fragments encoding a RT1 A beta chain. The nucleotide sequence of this cDNA insert was determined and was shown to encode a complete RT1 E beta chain. The RT1 E beta chain was highly homologous in terms of sequence identities to H-2 E beta and HLA-DR beta chains. Comparisons of predicted protein sequences of RT1, H-2, and HLA E beta and A beta chains showed that class II beta-chains are highly conserved with 105 out of 278 residues identical in all six beta-chains. The divergences in terms of the number of silent and replacement nucleotide substitutions between class II E beta or A beta sequences showed that the number of replacement substitutions reached a plateau after 10 million yr. Replacement substitutions therefore may be under selective pressure during evolution. The accumulation of silent and replacement substitutions in RT1 and H-2 class II beta-chains was faster than that in HLA beta-chain sequences. Thus, it appears that class II beta chains may be evolving at different rates in different species.

Amino Acid Sequence↗
PubMed1984

Sequence of a cDNA coding for a rat class II A alpha chain: extensive DNA and protein sequence identity to H-2 A alpha and HLA-DC1 alpha chains.

The rat major histocompatibility complex (RT1-B region) codes for two sets of class II molecules (Ia antigens) referred to as A and E. Each class II molecule is composed of two glycoprotein chains called the A alpha and A beta or E alpha and E beta. Two cDNA clones encoding rat A alpha chains were identified from cDNA derived from rat spleen mRNA using a combination of mRNA selection and colony hybridization techniques. The complete nucleotide sequence of the cDNA insert of one of these cDNA clones, pRIa.2, was determined. This sequence codes for the carboxy-terminal 129 amino acids of the rat A alpha chain and 293 nucleotides of 3' untranslated sequence. The rat A alpha chain was shown to be highly homologous in terms of both protein and DNA sequence identities to HLA-DC1 alpha and H-2 A alpha chains. Comparison between the coding regions of the cDNA insert of pRIa.2 and the corresponding region of a cDNA insert encoding an HLA-DC1 alpha chain showed sequence identities of 85% and 81% at the protein and DNA levels, respectively. Comparison between pRIa.2 and cDNA encoding an H-2 A alpha chain sequence showed identities of 91% for both protein and DNA. Results are discussed which strongly suggest that the class II A and E primordial genes arose by gene duplication prior to the evolutionary divergence of the mammals.

Amino Acid Sequence↗
PubMed1982

Mouse monoclonal antibodies against rat major histocompatibility antigens. Two Ia antigens and expression of Ia and class I antigens in rat thymus.

A rat Ia (RT-1B) antigen (called Ia-A) equivalent to the mouse I-A product has been defined with mouse monoclonal antibodies (W. R. McMaster and A. F. Williams, Eur. J. Immunol. 1979. 9: 426). To identify other Ia antigens mouse monoclonal antibodies were raised against rat spleen glycoproteins depleted of the Ia-A antigen. An IgG antibody (called MRC OX17) was obtained and used to purify a molecule which had a similar structure to the Ia-A antigen and reacted with anti-Ia alloantibodies. There was no cross-reaction between the two Ia glycoproteins in assays with mouse monoclonal antibodies, alloantibodies or rabbit antibodies. In one alloantiserum almost all the detectable anti-Ia antibodies reacted with a mixture of the two Ia glycoproteins. The MRC OX17 antibody did not bind to mouse cells, but rabbit antibodies to the pure rat glycoprotein cross-reacted and recognized determinants mapping to the mouse I-E region. In the thymus the rat Ia-E antigen was on cortical epithelial and medullary reticular cells. An IgG monoclonal antibody (MRC OX18) to isotypic determinants of rat histocompatibility RT-1A antigens was also produced and used to analyze these antigens on thymus cells. The heavily labeled thymocytes were those with characteristics of mature T lymphocytes. Cortical epithelial cells and medullary dendritic-like cells were also RT-1A positive.

Animals↗
PubMed1980

Two subsets of rat T lymphocytes defined with monoclonal antibodies.

A new monoclonal mouse antibody that recognizes a subset of rat peripheral T cells has been prepared by immunizing mice with rat thymocyte glycoprotein. This antibody, designated MRC OX 8, labels all peripheral T cells that are unlabeled by the previously described W3/25 monoclonal antibody. No peripheral T cells were found that bound both antibodies, but, in contrast, 90% of thymocytes were doubly labeled. Thoracic duct lymphocytes of congenitally athymic nude rats were not labeled by either antibody, but the spleens of such animals contained both W3/25+ cells and MRC OX 8+ cells. These splenocyte subpopulations did not overlap. Using the fluorescence-activated cell sorter to isolate cells binding MRC OX 8 antibody, the phenotype of T cells mediating various T cell functions was established. Combining the present results with those published previously, it is shown that the cells providing help for antibody responses and those mediating graft-vs.-host reactions are phenotypically W3/25+ MRC OX 8-. On the other hand, parental T cells that suppress antibody formation in F1 hosts were identified as W3/25- MRC OX 8+. The relationship between the rat T cell subsets defined by these antibodies and those in the mouse identified by the Ly series of alloantibodies is discussed and a comparison made between teh rat W3/25+ subset and a recently identified human T cell subset.

Absorption↗
PubMed1979

Purification with monoclonal antibody of a predominant leukocyte-common antigen and glycoprotein from rat thymocytes.

A leukocyte-common (L-C) antigen which can be dominant as an immunogen in rabbit anti-rat thoracic duct lymphocyte serum has been purified from rat thymocytes. Initially, an antigenic fragment of 100,000 apparent mol. wt. was prepared at 400 to 900-fold purification by lentil lectin affinity chromatography and gel filtration in deoxycholate. Mice were then immunized with this fraction, and a hybrid myeloma cell line secreting antibody to the L-C antigen was prepared by cell fusion. This antibody was used for affinity chromatography and gave pure L-C antigen at 1400-fold purification compared with thymocytes. The L-C antigen is a major membrane glyco-protein of rat thymocytes and has an apparent mol. wt. of 150,000 as determined by electrophoresis on polyacrylamide gels in sodium dodecyl sulfate. The antigen constitutes one of the three thymocyte glycoproteins which stain intensely for carbohydrate with periodic acid Schiff stain. It is present on greater than 95% of thymocytes, bone marrow cells and thoracic duct lymphocytes.

Animals↗
PubMed1979

A monoclonal mouse anti-rat Ia antibody which cross reacts with a human HLA-DRw determinant.

A mouse monoclonal antibody, called MRC OX 3, which detects a polymorphic Ia determinant in the rat and cross reacts with an Ia determinant coded for by the I-A subregion in the mouse, detects a polymorphic determinant on human B cell lines. MRC OX 3 antibody binds to human B cell lines which express HLA-DRw specificities DRw 1, DRw2 and DRw6 but does not bind to those cells which only express other HLA-DRw specificities. No significant binding of MRC OX 3 antibody to either normal or mitogen stimulated human peripheral blood leukocytes, some of which are typed as HLA-DRw1, DRw2 or DRw6, could be detected. The binding of MRC OX 3 antibody to a human B cell line could be completely inhibited by pre-absorbing the antibody with purified rat Ia antigen.

Animals↗
PubMed1975

Subcellular fractions from dermis and epidermis in contact sensitization of guinea pigs to 1-chloro-2,4-dinitrobenzene.

Subcellular fractions were prepared from the epidermis of guinea pigs which had been painted with 1-chloro-2,4 dinitrobenzene 14 h previously. The microsomal fraction showed less activity than other fractions in the MIF test. Similarly, the microsomal fraction from the dermis of skin irritated with croton oil before DNCB painting was relatively inactive. However, the microsomal fractions from the epidermis and more especially from the dermis of skin painted with DNCB while undergoing allergic contact dermatitis from pentadecylcatechol showed significant MIF activities.

Alkanes↗