bluuebunny/crossref_metadata_2025_split huggingface dataset:
BRIC 18: A MONOCLONAL ANTIBODY WITH A SPECIFICITY RELATED TO THE KELL BLOOD GROUP SYSTEM
Authors: Parsons S. F. , Judson P. A. , Anstee D. J. 
Published: April 2007

SUMMARYA mouse monoclonal antibody (NBTS/BRIC 18) has been produced which has a specificity related to the Kell blood group system. BRIC 18 does not react with human erythrocytes of the Ko phenotype and reacts only very weakly with those of the McLeod phenotype.
IMMUNOLOGICAL CROSS‐REACTIVITY BETWEEN H‐2DK PRODUCT AND DTIC ‐ TREATED H ‐ 2d LYMPHOMA
Authors: Marelli Ornella , Testorelli Carla , Canti G. , Festenstein H. , Nicolin A. 
Published: April 2007

SUMMARYThe experiments reported here concern the charcterization by techniques of in vitro cell‐mediated immunity of the antigens induced by 5‐(3,3'dimethyl‐1‐triazine)‐imidazole‐4‐carboxamide (DTIC) on L1210, a chemically‐induced lymphoma of DBA/2 mice (H‐2d). This series of experiments with the DTIC‐treated L1210 tumour show the presence of an H‐2D'‐like antigen which resembles the Dk gene product/s of the H‐2k haplotype.
GENETIC CONTROL OF CELL‐MEDIATED IMMUNITY IN THE RAT:II. SHARING OF EITHER THE RTI. A OR RTI. B LOCUS IS SUFFICIENT FOR TRANSFER OF ANTIMICROBIAL RESISTANCE
Authors: Jungi T. W. , Kunz H. W. , Gill T. J. , Jungi Ruth 
Published: April 2007

SUMMARYThe MHC restriction criteria for T cells activating macrophages in vivo and mediating antimicrobiol resistance to Listeria monocytogenes were determined. Antimicribiol resistance could be transferred by T cell in order of decreasing efficiency from syngeneic. RT1A. compatible, RTI.B compatible and RT1 incompatible donors. Alloreactive T cells responding to either A locus or B locus encoded antigens in a graft‐versus‐host reaction were also able to activate macrophages. Approximately five times as many MLC‐reactive precursors responded to B locus alloantigens as to A locus alloantigens, but A‐resticted Listeria‐specific T cells wre considerably more numerous (or more efficient) in Listeriainfected hosts than were B‐restricted, Listeria‐specific T cells. This was unexpected, since A‐restricted, Listeria‐specific T cells failed to transfer delayed hypersensitivity (DTH) to soluble bacterial antigens.
GENETIC CONTROL OF CELL‐MEDIATED IMMUNITY IN THE RAT! III. T CELLS RESTRICTED BY THE RT1.A LOCUS RECOGNIZN VIABLE LISTERIA BUT NOT LSOLATED BACTERIAL ANGIGENS
Authors: Junci T. W. , Gili III T. J. , Kunz H. W. , Jungi Ruth 
Published: April 2007

SUMMARYThis study nvestigates the dicordance between the restriction criteria required for the transfer of cellular resistance to Listeria monocytogenes (LM) and those for the transfer of delayed type hypersensitivity to Listeria antigens. Infective bacteria elicity both RTl.A‐restricted T cells and RT1.B.‐restricted T cells. Both populations of t cells mediate lymphoblast localization and macrophage accumulation, which are reactions characteristic of delayed type hypersensitivity (DTH), and cause macrophage activation with rapid and efficient bacterial elimination, which is an expression of cellular resistance. If alcohol‐killed Listeria organisms (pLMA) are injected, only the RTl.B‐restricted T cell subset is triggered. Direct comparison of lymphoblast localization in LM infection sites and the expression of resistance of resistance revealed that efficient resistance may be mediated by small numbers of lymphoblasts and that below a certain threshold there is no correlation between lymphoblast localization and the level of resistance.
IgG AND IgA HEAVY CHAIN ALLOTYPES IN TYPE 1 DIABETES
Authors: Bertrams J. , Schoeps L. , Baur M. P. , Luboldt W. , Loghem E. van 
Published: April 2007

SUMMARYIgG and IgA heavy chain allotypes were determined in the sera of 483 Caucasian Type 1 diabetes patients and 503 Caucasian healthy controls. There was no significant difference between patients and controls neither on the level of Gm phenotype frequencies nor on the level of Gm three‐locus and two‐locus haplotype frequencies. A selective IgA deficiency was found in 14 patients (2.9%) but in none of the control individuals (P<10‐4).
THE INCIDENCE OF Gm AND Km ALLOTYPES IN A GROUP OF BRETONS, THE BIGOUDENS
Authors: Youinou P. , Golmard J. L. , Rivat‐Peran Liliane , Salmon Denise , Menn G. Le , Ruffie J. , Salmon C. 
Published: April 2007

SUMMARYImmunoglobulin allotypes were studied in a peculiar Breton community, the Bigoudens. Results showed that the incidence of the common Gm and Km phenotypes fell into the ranges quoted for Caucasian populations, except for the Gm1;…5,10,11,13,14 and Gm1,2;…5,10,11,13,14. The frequencies were found to be significantly different from those of non‐Bigouden Breton neighbouring controls.
H‐2K RESTRICTION OF THE T CELL‐MEDIATED LYSIS OF A CHEMICALLY‐INDUCED BALB/c FIBROSARCOMA
Authors: Colombo M. P. , Rodolfo Monica , Parmiani G. 
Published: April 2007

SUMMARYPrevious work has shown that a cytotoxic T lymphocyte (CTL) immune response of syngeneic mice immunized with a chemically‐induced BALB/c (H‐2d) fibrosarcoma was directed against an individual tumour‐associated antigen. To see whether this reaction was restricted by products of the major histocompatibility complex (MHC), anti‐H‐2 alloantisera to K or D antigens were used to interfere with the CTL‐mediated immune response. Antisera to Kd but not to Dd antigens inhibited the lytic activity of CTL against fibrosarcoma cells. In addition, the study of the CTL response in F1→ P antitumour immunized chimeric mice showed that antitumour cytotoxicity developed only when F1 and parental host shared the Kd region. Both experiments strongly indicate that recognition of the individual tumour‐associated antigen of the BALB/c fibrosarcoma is restricted by the products of H‐2Kd genes.
IMMUNOGLOBULIN ALLOTYPES IN ABORIGINAL POPULATIONS OF THE TAIMIR PENINSULA
Authors: Osipova,and L. P. , Sukernik R. I. 
Published: April 2007

SUMMARYSerum blood samples from 563 of the total 700 Nganasans, members of the isolate in the northern‐most part of Siberia were tested for G1m, (z,a,x,f), G2m (n), G3m (g,b0,b1,b3,b5,s,t), and km (1) allotypic determinants. Additionally, 78 Yenisey Samoyeds (Entsi) who are the Nganasan's western neighbours were studied. Both populations are remarkable for high frequency of ‘Northern Oriental’Gm (za;.;b0b3b5st) which appears to be the most frequent haplotype in the Nganasans (0.486), and is the second frequent in Yenisey Samoyeds (0.276). The Gm (f;b) generalized haplotype which used to be considered as an indicator of Caucasian gene flow occurred in the Nganasans in the very low frequency of 0.008, versus 0.045 revealed in adjoining Yenisey Samoyeds. Both populations also differ in the frequency of Km1 which is two times lower in the Nganasans (0.048), than in Yenisey Samoyeds (0.103). When segregation ratios for the Gm locus were inspected in 67 Nganasan families, no apparent deviations from Mendelian expectations, and no recombinant phenotypes were observed.
C6 LINKAGE STUDIES
Authors: Bender K. , Bissbort S. , Mayerová A. , Mauff G. , Wienker T. F. 
Published: April 2007

SUMMARYNo evidence was found for close linkage between the human C6 gene (6th component of complement) and 28 marker loci, using the LIPED 3 computer program of Ott (1974). But the data allow the exclusion of the C6 locus from large parts of the autosomes 1, 2, 4, 6, 8, 9, 13, 14, 16, 19, and 20.
THE H‐Y ANTIGEN AND ITS FUNCTIONS: A REVIEW AND A HYPOTHESIS
Authors: Polani P. E. , Adinolfi M. 
Published: April 2007

SUMMARYHaving reviewed the status of H‐Y as the sex‐determining antigen concerned with the differentiation of teh dominant gonad, we consider some of the problems deriving from the tests for this antigen, and from their application to the study of natural experiments. To reconcile the results of these studies with the alleged influence of H‐Y on gonadal development, we propose and discuss a hypothesis on the genetic control of the synthesis of this antigen. This states that an autosomally‐coded, positively cross‐reacting precursor is rendered biologically active by a Y‐chromosomal gene, and transformed (in a dosedependent manner) into a biologically inactive, antigenically negative substance under the influence of an X‐chromosomal gene.
GENETIC CONTROL OF THE IMMUNE RESPONSE TO MYOGLOBIN: XVI. CONTROL OF ANTIBODIES WITH PRESELECTED SPECIFICITIES FOLLOWING IMMUNIZATION WITH FREE SYNTHETIC PEPTIDES REPRESENTING THE ANTIGENIC SITES OR SURFACE NON‐IMMUNOGENIC LOCATIONS IN THE PROTEIN
Authors: Young C. R. , Schmitz H. E. , Atassi M. Z. 
Published: April 2007

SUMMARYPrevious studies in this laboratory have resulted in the determination of the antigenic structure of myoglobin. The present work was carried out to investigate the genetic control of the murine antibody response to myoglobin following immunization with free (i.e., not coupled to a carrier) synthetic antigenic sites or other peptides corresponding to surface regions of myoglobin that are not immunogenic when the native molecule is the immunizing antigen. Synthetic peptides corresponding to antigenic site 1 (peptide 15‐22), site 2 (peptide 56‐62), site 3 (peptide 94‐100), site 4 (peptide 113‐120), site 5 (peptide 145‐151) and two surface regions, peptide 1‐6 and peptide 121‐127, were injected in complete Freund's adjuvant in different strains of mice. Serum antibodies specific for myoglobin were subsequently obtained and were measured by means of a radioimmune plate binding assay in which Mb was used as the solid phase antigen. It was found that the genetic control of the antibody response to myoglobin following immunization with the free synthetic peptides was different from the genetic control obtained following immunization with native myoglobin. The significance of this finding is discussed.
BIOCHEMICAL CHARACTERIZATION OF HUMAN THY‐1
Authors: Bonewald L. , Ades E. W. , Tung E. , Marchalonis J. J. , Wang A. C. 
Published: April 2007

SUMMARYThe human Thy‐1 homologue (p25) was characterized biochemically for amino acid composition, sequence and carbohydrate content. Two other forms of the human Thy‐1 molecule were detected and partially characterized. A 40,000 mol.wt. molecule (p40) is the dimer of p25 and its formation is increased by the presence of sodium dodecyl sulphate (SDS). The second form of 16,000 mol.wt. (p16) appears to be a cryptic or breakdown form of p25. Comparison of the amino acid compositions of p25, p40 and p16 isolated from MOLT‐3 cells, with that deduced from the nucleotide sequence of the gene coding for part of the putative T cell antigen receptor, also from MOLT‐3 cells, shows that the Thy‐1 homologue is distinct from, but evolutionary related to, one of the putative T cell antigen receptor polypeptide chains.
RESTRICTED EXPRESSION OF LW ANTIGEN ON SUBSETS OF HUMAN B AND T LYMPHOCYTES
Authors: Oliveira O. L. P. , Thomas D. B. , Lomas C. G. , Tippett P. 
Published: April 2007

SUMMARYNIM‐M8 is a monoclonla IgM antibody, specific for the LWab antigen as shown by its reaction with red cells of all donors except those lacking LWa, LWb and LWab. Indirect immunofluorescent staining and cell sorter analyses have shown that LWab is present on a subpopulation of human lymphoctes. Cell fractionation studies indicate that subsets of both B and T cells express LWab and it may, therefore, provide a further marker for heterogeneity in these lymphocyte populations.
INFLUENCE OF NON‐H‐2 GENES ON THE IN VIVO RESPONSE TO PENICILLIN‐TREATED AUTOLOGOUS PLATELETS
Authors: Claas Frans H. J. , Blankert J. J. (Han) , Rooduyn‐Moerel Letty , Rood Jon J. van 
Published: April 2007

SUMMARYMice of different inbred strains were injected intravenously on day O and 6 with autologous platelets incubated in a penicillin solution. After the second injection mice of most strains died immediately with anaphylactic symptoms. Both passive transfer experiments and indirect immunofluorescence studies suggest that a serum factor (probably IgM) is involved in this phenomenon. Only mice with a C3H background were unable to respond to autologous penicillintreated platelets, although C3H platelets did induce a lethal response in B10.A mice. Experiments in which B10.A mice were primed with autologous penicillin‐treated platelets and rechallenged with allogeneic penicillin‐treated platelets, showed that the response is directed against a polymorphic non‐H‐2 antigen in combination with penicillin.
T CELL RECOGNITION OF LYSOZYME IV. LOCALIZATION AND GENETIC CONTROL OF THE CONTINUOUS T CELL RECOGNITION SITES BY SYNTHETIC OVERLAPPING PEPTIDES REPRESENTING THE ENTIRE PROTEIN CHAIN
Authors: Bixler Garvin S. , Yoshida Takeshi , Atassi M. Zouhair 
Published: April 2007

SUMMARYRecently, this laboratory has developed a comprehensive strategy for the systematic localization of all the ‘continous’ antigenic (as well as other binding) sites of complex multivalent protein antigens involved in B and T cell recognition. The strategy depends on the syntheis of consecutive overlapping peptides that together account for the entire protein chain. This strategy was applied here for the localization of the ‘continuous’ T cell recognition sites of hen egg lysozyme. Eight overlapping peptides encompassing the entire protein chain of lysozyme were synthesized and examined for their ability to stimulate in vitro proliferation of T cells from several mouse strains (A/J, H‐2a; BALB/c and DBA/2, H‐2d; B10.BR, H‐2k; DBA/1, H‐2a; SJL, H‐2s) that had been primed with native lysozyme. This approach enabled the identification of a full profile of in vitro active lysozyme peptides and the localization of four major T cell recognition sites, three of which were subject to individual control.
T CELL RECOGNITION OF MYOGLOBIN : LOCALIZATION OF THE SITES STIMULATING T CELL PROLIFERATIVE RESPONSES BY SYNTHETIC OVERLAPPING PEPTIDES ENCOMPASSING THE ENTIRE MOLECULE
Authors: Bixler Garvin S. , Atassi M. Zouhair 
Published: April 2007

SUMMARYA comprehensive strategy for the systematic localization of all continuous antigenic sites within a protein has previously been introduced by this laboratory. The strategy consists of studying the immunochemical activity of a series of consecutive synthetic peptides that encompass the entire protein chain and the are uniform in size and in overlap at their N and C‐terminals with neighbouring peptided. By application of this strategy to sperm whale myoglobin, we have been able to delineate the ontinuous sites of T cell recognition of myoglobin in three high responder mouse strains. Thirteen 17‐residue peptides that encompass the entire myoglobin chain and overlap by five residues at both ends were synthesized, purified and characterized. The peptides were examined in vitro for their ability to stimulate lymph node cells from myoglobin‐primed DBA/2 (H‐2d), BALB/c (H‐2d) and SJL (H‐2s) mice as well as long‐term cultures of myoglobin‐specific T cells. Several regions of the moleculr (T sites) were founnd to stimulate myoglobin‐primed lymph node cells and myoglobin‐specific long‐term T cell cultures. This strategy has enabled the localization of the full profile of dominant sites of T cell recognition in myoglobin for these mouse strains. Of these T sites, one region, residues 107‐125, was clearly immunodominant in these strains and was found to coincide with the antigenic (i.e. antibody binding) site 4 of myoglobin. Also, other regions stimulated T cells and appeared to coincide with previously known antigenic sites. It is noteworthy that, in addition to sites recognized by both T and B cells, the protein has other sites which are recognized exclusively by T cells and to which no detectable antibody response is directed.
C4* A6BQO: A NEW C4 HAPLOTYPE
Authors: Skanes Verna , Larsen Bodil 
Published: April 2007

SUMMARYA C4 haplotype containing C4*A6 without C4*B1 is described. It occurred in the MHC haplotype HLA‐AL, Cw5, Bw44, C2*1, BF*S, C4*A6BQO, DR3, GLO 2. This haplotype was observed in five of eight siblings, including the propositus who was in renal failure. The C4A6 was not haemolytically active and this new haplotype is therefore of particular interest since it is functionally equivalent to the rare C4‐deficient haplotype C4*AQOBQO.
ANTIGEN BINDING TO LYMPHOID CELLS FROM UNIMMUNIZED MICE
Authors: DeLuca D. 
Published: April 2007

SUMMARYNeonatal spleen populations have been studied for antigen‐binding capacity in an attempt to determine if the frequency of double antigen‐binding cells changes as the population matures. Just after birth, the frequencies of total ABC, double ABC and Ig‐bearing cells were similar to the frequencies seen in the adult bone marrow. During the first week after birth, the proportion of total ABC and Ig‐bearing cells rose sharply so that by 8 days after birth, these cells were about half of adult levels. The proportion of total double ABC, after a brief rise at day 1, remained constant throughout the test period. Thus, the proportion of total ABC which are doubles gradually decreases with age. Sedimentation velocity studies indicate that double ABC's tend to co‐sediment with cells which require a period of maturation before they can respond to a thymus‐independent antigen in irradiated hosts. Single ABC, on the other hand, tend to co‐sediment with cells which are immediately responsive to antigen, or require a shorter maturational period before they become responsive to antigen. All of these data, taken together with our other work, suggest the possibility that multiple ABC are clonally‐derived lymphocyte populations which become more restricted in their antigen‐binding capacity as they mature.
GENETIC LIMITS OF THYMIC IMMUNOSUPPRESSION OF ANTI‐HAPTEN ANTIBODY PRODUCTION IN XENOPUS LAEVIS LAEVIS, THE SOUTH AFRICAN CLAWAD TOAD
Authors: Ruben L. N. , James Heidi S. , Clothier R. H. , Balls M. 
Published: April 2007

SUMMARYThymic immunosuppression in adult Xenopus laevis laevis, the South African clawed toad, is antigen‐dependent and antigen‐specific, but it is not genetically restricted. In this report, we show that combination in vitro with a thymus from an immunized Xenopus laevis laevis can suppress antibody production to a hapten from spleen fragments, if the spleen fragments are derived from a subspecies of Xenopus laevis or a species of Xenopus which shares the same diploid chromosome number (2N = 36). Some aspects of the evolution of thymic immunosuppression are considered in the light of these results.
AN INTERESTING MONOCLONAL ANTI‐N PRODUCED FOLLOWING IMMUNIZATION WITH HUMAN GROUP O, NN ERYTHROCYTES
Authors: Fletcher A. , Harbour C. 
Published: April 2007

SUMMARYSpleen cells from Balb/c mice given multiple injections of intact human erythrocytes (group O, NN) were fused with NS1 myeloma cells. Culture fluids from the resulting hybrid cells were screened for agglutinating antibody against a panel of erythrocytes. One cell line, 2/23, secreted an IgM antibody which reacted more strongly with NN than with MM cells. Neuraminidase or papain treatment of erythrocytes abolished agglutination whereas trypsin treatment did not. Reactions with U‐erythrocytes of different MN phenotypes confirmed the anti‐N specificity of monoclonal antibody 2/23. This is the first report of monoclonal anti‐N stimulated by the immunization of mice with intact erythrocytes.
VARIATION IN H‐2 ANTIGEN EXPRESSION ON LYMPHOMYELOID CELLS IN SEMI‐ALLOGENEIC IRRADIATION CHIMERAS
Authors: O'Neill Helen, C. , Ashman R. B. , Gallagher P. F. , Woodhams C. E. , Blanden R. V. 
Published: April 2007

SUMMARYSpleen cells from 30 individual murine irradiation chimeras of the type (P1 x P2)F1→ P1 were compared in a rosetting assay for H‐2K and H‐2D cell surface antigen expression with normal (P1 x P2)F1 hybrid controls. Eleven out of the 30 chimeras were in the normal range, but the other 19 differed from F1 controls by 4‐ to 100‐fold in endpoint titre for at least one H‐2K or H‐2D antigen. Every possible class of variation was found, i.e. up or down variation of H‐2K or H‐2D antigens of P1 or P2 type. This evidence, together with data from T6 chromosome marker experiments which also showed full reconstitution of lethally irradiated P1 recipients by (P1 x P2)F1 donor lymphomyloid stem cells, suggested that incomplete reconstitution was not the cause of H‐2 antigenic variation.Low expression of P2 H‐2 antigens on spleen cells derived from (P1 x P2)F1→ P1 chimeras was investigated further. Fifteen lethally irradiated (P1 x P2)F1 recipients of bone marrow cells from two such chimeras were all of normal F1 H‐2 phenotype when tested 10‐12 weeks after reconstitution, thus excluding stable, low P2 H‐2‐expressing variant F1 stem cells as a cause of the phenomenon. If P1 recipients were hyperimmunized against P2 cells before lethal irradiation and reconstitution with (P1 x P2)F1 stem cells, there were significantly fewer Till‐McCulloch colonies in their spleens 10 days after reconstitution than in spleens of unimmunized controls. Also > 90% of immunized recients died by 6 weeks after stem cell injection but two survivors both showed very low levels of P2 H‐2K and H‐2D antigens. These results together with previously published evidence of anti‐P2 Tc cell activity and P2 skin graft rejection in (P1 x P2)F1→ P1 chimeras suggested that residual anti‐P2 immunological capability in lethally irradiated P1 recipients may be associated with low P2 H‐2 expression on their F1‐derived spleen cells, although the mechanism does not involve selection of stable, variant F1 stem cells. The mechanism(s) of other classes of variation in H‐2 expression in (P1 x P2)F1→ P1 chimeras were not investigated.
TWO UNLINKED GENETIC LOCI INTERACT TO CONTROL THE HUMAN IMMUNE RESPONSE TO TYPE III GROUP B STREPTOCOCCAL ANTIGEN
Authors: Pandey J. P. , Baker Carol J. , Kasper D. L. , Fudenberg H. H. 
Published: April 2007

SUMMARYSerum samples were collected from 30 healthy adult Caucasian volunteers before and after immunization with native type III polysaccharide of group B streptococcus. Serum antibody to this polysaccharide was measured and sera were typed for several Gm and Km(1) allotypes. A significant interactive effect of Gm(23) and Km(1) was found on immune responsiveness to native type III group B streptococcus polysaccharide antigen.
EVIDENCE OF ONLY ONE H‐2D/L ‐ RELATED GLYCOPROTEIN IN H‐2dm1 MUTANT CELLS
Authors: Hunt Pamela , Burnside,and Stephen S. , Sears Duane W. 
Published: April 2007

SUMMARYAnalyses of the H‐2D/L‐related glycoproteins from dm1 mutant cell extracts by sequential immunoprecipitation, by SDS gel electrophoresis and by tryptic peptide mapping indicate that dm1 cells express only a single glycoprotein with H‐2D/L‐related determinants. In contrast to the four H‐2D/L‐related antigens identified for the parental d haplotype viz. H‐2Dd, H‐2Md, H‐2Ld and H‐2Rd, separate and distinguishable “H‐2Ddm1”, “H‐2Mdm1”, “H‐2Ldm1” and “H‐2Rdm1” glycoprotein counterparts are apparently lacking in the dm1 mutant haplotype. Only a single H‐2D/L‐related glycoprotein is identified in dm1 extracts by standard serological methods and this glycoprotein is designated H‐2D/Ldm1 because of its H‐2Dd/H‐2Ld hybrid characteristics, as recently shown by Burnside and colleagues (1984). Thus, the seemingly complex phenotype of the dm1 mutant appears to originate primarily from one molecule having properties of two (or more) molecules of the parental haplotype.
ELECTROPHORETIC ANALYSIS OF HLA‐DR2 MOLECULES ISOLATED FROM HLA‐Dw2 AND HLA‐Dw 12 CELL LINES
Authors: Takenouchi* T. , Kasahara M. , Ogasawara K. , Ikeda H. , Ishikawa N. , Hawkin S. , Wakisaka A. , Aizawa M. 
Published: April 2007

SUMMARYTo answer the question of whether or not polymorphism exists among HLA‐DR2 molecules derived from cells homozygous for HLA‐DR2, but expressing different HLA‐D specificities, HLA‐DR2 molecules were isolated from HLA‐Dw2 and HLA‐Dw12 homozygous cells using a monoclonal antibody operationally monospecific for HLA‐DR2, and were compared to each other by two‐dimensional gel eletrophoresis. No electrophoretically discernible polymorphism was found in either the heavy or the light chain subunits of the HLA‐DR2 molecules. These findings are in marked contrast with previous observations that each of the HLA‐DR4‐associated HLA‐D clusters expresses an electrophoretically distinct HLA‐DR4 light chain.