HL-A Inhibiting Activity in Human Seminal Plasma

THE HL-A antigens of man have been described on a number of somatic (diploid) cells¹ and demonstrated on spermatozoa, suggesting an expression of the haploid genome on spermatozoan membrane². Soluble HL-A antigens, HL-A2, HL-A7 and 7b, have been reported in serum^3,4. We have now found in human seminal plasma substances that inhibit specific anti-HL-A antibodies. This has important biological and clinical implications, especially for the characterization of HL-A antigens and for the induction of specific tolerance.     

HL-A population studies in 445 individuals from Hamburg,respecting 8 LA and 15 Four-antigens including U 18 (W 16) and CM (W 18)

Summary By means of 8 LA (HL-A1, HL-A2, HL-A3, HL-A9, HL-A10, HL-A11, Ba^*, Li) and 15 Four-antisera specificities (HL-A5, HL-A7, HL-A8, HL-A12, HL-A13, R^*, BB, MaKi, LND, U 18, MaPi, CM, ET, AA, FJH) 92% of the LA and 92% of the Four-alleles were identified in 445 unrelated people from Northern Germany (Hamburg). The allele frequencies of the more recently described antigens CM and U 18 are 1.3 and 2.6%, respectively. Both alleles are significantly associated with HL-A10.

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Zusammenfassung Bei Verwendung von 8 LA-(HL-A1, HL-A2, HL-A3, HL-A9, HL-A10, HL-A13, Ba^*, Li) und 15 Four-Antiserenspezifitäten (HL-A5, HL-A7, HL-A8, HL-A12, HL-A13, R^*, BB, MaKi, LND, U 18, MaPi, CM, ET, AA, FJH) konnten an 445 nichtverwandten Personen aus dem norddeutschen Raum 92% aller LA- und 92% aller Four-Allele identifiziert werden. Die Allelhäufigkeiten der erst seit kurzer Zeit beschriebenen Allele CM und U 18 betragen 1,3 bzw. 2,6%. Beide Allele zeigen eine signifikant hohe gametische Assoziation zu HL-A10.

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Supported by the Deutsche Forschungsgemeinschaft.     

Die Genetik des HL-A-Systems

Zusammenfassung Die Analyse der Gewebstypen von 300 nichtverwandten Personen der österreichischen Bevölkerung und von 110 Familien mit 381 Kindern, die erstmals in diesem Umfang vorgenommen wurde, bestätigt die formalgenetische Hypothese der Vererbung des HL-A-Systems. Dieses System wird über 2 eng gekoppelte Loci eines Autosoms, den LA- und den 4-Locus, gesteuert, wobei an beiden Loci multiple Allelie vorliegt und die einzelnen Merkmale einen dominanten Erbgang aufweisen. Die Genfrequenzen der HL-A-Gene und die Haplotypenfrequenzen wurden errechnet. Die Häufigkeit der Rekombinationen innerhalb des HL-A-Systems wurde mit 0.38% ermittelt. Es wurde kein Anhaltspunkt für eine Selektion bei der Vererbung der HL-A-Merkmale gefunden. Basierend auf den formalgenetischen Untersuchungen wurde die Brauchbarkeit (Vaterschaftsausschlußchance) und die Wertigkeit (Beweiswert) des HL-A-Systems diskutiert. Zur Berechnung der Vaterschaftsausschlußchance wurde eine Formel, die das Koppelungsungleichgewicht der 2 Loci des HL-A-Systems berücksichtigt, entwickelt.

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The genetics of the HL-A-System A study of population and families and its application in paternity cases

Summary 300 unrelated individuals of the Austrian population and 110 families with 381 children have been typed by means of the microlymphocytotoxic test. The analysis of the results of this study shows that the HL-A-antigens are governed by 2 closely linked loci of an autosomal chromosome, the LA-locus with the genesHL-A1, HL-A2, HL-A3, HL-A9, HL-A10, HL-A11, Ba ^*,Li and the 4-locus with the genesHL-A5, HL-A7, HL-A8, HL-A12, HL-A13, R ^*,BB, FJH, MaKi, AA, MaPi, LND andET. Further, it was found that there must exist more antigens, which are not yet serologically detectable, within both loci. The genes of the HL-A-system are inherited as codominant characters. The gene frequencies of the individual determinants and the haplotype frequencies are calculated. The recombination frequency within the HL-A-system was found to be 0.38%. No evidence with regard to a selection could be recognized analysing the inheritence of the HL-A-genes. Basing on the genetical analysis, the efficiency of the HL-A-system in paternity cases is discussed. The chance of exclusion in false accusations of paternity was calculated by means of a formula developed for this purpose, which takes into account the linkage disequilibrium between the LA- and the 4-locus, and was found to be approximatively 76%.

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National Blood Group Reference Laboratory (WHO), National Tissue Typing Reference Laboratory (Council of Europe).     

Association of HL-A antigens andβ 2-microglobulin at the cellular and molecular level

Surfaces of cultured human lymphoid cells RPMI 1788, RPMI 4098, RPMI 8866, Raji, and WI-L2 were found to contain bothβ ₂-microglobulin (β ₂-μ) and HL-A determinants when tested by direct complement-dependent cytotoxicity andquantitative absorption with different cytotoxic antiβ ₂-μ antisera and specific HL-A alloantisera. The same antigenic specificities were found in 3M KCl extracts of these cultured cells with a sensitiveβ ₂-μ radioimmunoassay and an HL-A antigen blocking assay. Daudi cells provided a contrast, since noβ ₂-μ or HL-A determinants were found on their surfaces or in 3 M KCl extracts prepared from them. Results from specific antibody blocking tests suggest a close association betweenβ ₂-μ and HL-A determinants on plasma membranes of cultured human lymphoid cells. A solid state immunoadsorbent containing antiβ ₂-μ antibodies effectively removed all detectable HL-A antigenic activity from some 3M KCl extracts of cultured human lymphoid cells as well as from some sera. Adsorption of HL-A antigens to these immunoadsorbents was specific since it was blocked only by prior addition ofβ ₂-μ. Once on the antiβ ₂-μ immunoadsorbents, HL-A antigens still reacted specifically with HL-A alloantibodies in quantitative absorption experiments. HL-A antigens andβ ₂-μ could be eluted from antiβ ₂-μ immunoadsorbents with a variety of chaotropic reagents and detergents, but thus far potassium bromide and sodium dodecyl sulfate (SDS) appear to be the most effective. SDS-PAGE of these eluates indicated that HL-A antigens were considerably purified by adsorption to antiβ ₂-μ immunoadsorbents and that two major molecular size fragments were distinguishable, i.e., ∼33,000 for HL-A and ∼ 12,000 forβ ₂-μ.     

Specificity of Cellular Immune Reactivity to Virus-induced Tumours

SPECIFICITY is one of the chief hallmarks of immune reactions. In many cases, specificity has been defined by reactivity against some antigens and not against others, but the results of direct tests may be misleading. In many cases, in transplantation and tumour immunology, direct reactivity may be absent in spite of the presence of the antigen. With HL-A antigens, the CYNAP phenomenon (cytotoxicity negative, absorption positive) has been described¹. Virus-induced tumours may have relatively small amounts of tumour specific cell surface antigens which are detectable only by absorption tests^2,3. In addition, immune reactions may occur against a particular antigen on one material and against different antigens on another material. With antibody reactions, specificity can be confirmed by the appropriate absorption experiments^4,5. With cellular immune reactions, comparable demonstration of specificity has been very difficult.     

Inverse Relationship of Polyoma Tumour Specific Cell Surface Antigen to H-2 Histocompatibility Antigens

NEOPLASTIC transformation is known to be associated with changes in the strength of normal cellular antigens, but the effect can be either an increase or a decrease. In the former category are Forssman antigens in guinea-pig hepatoma¹ and SV40 transformed cells²; HL-A antigens in leukaemic cells³; and “G” antigen in human tumour cells⁴. On the other hand, the intensity of the expression of mouse H-2 histocompatibility antigens is decreased in TL(+) leukaemia⁵ and methylcholanthrene (MCA)-induced tumours⁶. We set out to tell whether the expression of histocompatibility antigens was also affected by transformation with an oncogenic virus and have found that in tumours induced by polyoma virus, the quantity of H-2 antigens varied inversely with the amount of tumour-specific cell surface antigen.     

The identification of HL-A antigens on fresh and cultured human endothelial cells.

Human endothelial cells were obtained from the umbilical cord veins of 16 newborns by methods previously described and tested for HL-A antigens by a microcytotoxicity method. HL-A antigens were present on all endothelial cell lines tested. When the HL-A phenotypes of fresh endothelial cells and autologous fetal lymphocytes were compared, a concordance of 70% was observed. When the HL-A phenotypes of maternal lymphocytes and fresh endothelial cells were compared, a maternal contribution to the endothelial cell phenotype was evident in 72% of the possible commmon antigens. Some HL-A antigens were deleted from 11 of 16 endothelial cell lines that were re-typed after 2 weeks in tissue culture. The majority (90%) of deleted antigens were from the second HL-A locus. When three lines of endothelials cells were again re-typed after 6 weeks in culture, no further changes in antigenicity were noted. These findings: a) demonstrate that HL-A antigens are present on human endothelium and suggest that endothelial cells are actively involved in establishing the immunogenicity of a graft, and b) demonstrate that the HL-A antigens on human endothelial cells may be modulated by in vitro culture.     

Some biological properties of beta2-microglobulin and its antibody.

beta2-Microglobulin on the surface of lymphocytes exists in two molecular forms, first as part of the HL-A antigen complex, and second as a free molecule unbound to other membrane macromolecules. Quantitative determinations of the numbers of molecules of beta2-microglobulin per lymphocyte when compared to published values for the numbers of HL-A molecules per cell are consistent with an excess of beta2-microglobulin compared to HL-A antigens on the cell surface. Turnover studies of beta2-microglobulin from the lymphocyte surface indicated that both beta2-microglobulin and HL-A components are metabolized at similar rates. beta2-Microglobulin appears to be released in the free form. HL-A antigens, if released from the cell surface, appear to be released unbound to beta2-microglobulin. The effects of anti-beta2-microglobulin antibody on lymphocyte activation, namely on the mixed lymphocyte reaction and on antigen induced proliferative response, were studied. Anti-beta2-microglobulin completely inhibited the mixed lymphocyte reaction and the antigen induced proliferative response.     

The effect of heating and drugs on HL-A antigens and their reactions with cytotoxins]

In some instances the heating of lymphocytes for 2 to 3 minutes at 56 degrees C enhances HL-A antigens or makes it possible to detect these antigens by a twostage microlymphocytotoxic test on preheated lymphocytes only. Similar phenomenons are observed in some tannin (1: 40 000) or 0.1% phenol-treated lymphocytes and after the addition of these solutions during the first stage of the lymphocytotoxic test. Prolonged heating at 56 degrees C leads to nonspecific polyreactivity of lymphocytes, giving false results with all sera. For similar reasons also higher concentrations of tannin and phenol solutions were found dissatisfactory for the pretreatment of lymphocytes. The pretreatment of lymphocytes with 36-0.5% formaline induces full inhibition of specific cytotoxic reactivity of HL-A antigens and their absorption ability with regards to respective HL-A sera. The addition of formaline at 0.06-0.3% concentration during the first and second stages of the test and at the end of the second stage (or simultaneously with eosine) gives also negative results of the cytotoxic test owing to the inhibitory effect of formaline on rabbit complement and HL-A antigens.     

Cross-reactivity between human and murine lymphocyte antigens: III. Reactivity of H-2 allo- and xenoantisera with human lymphoid cells

H-2 alloantisera and antimouse lymphocyte xenoantisera react with 14%–100% of human lymphocytes from a panel of at least 80 unrelated people. Population and family studies did not reveal HL-A specificity of such lymphocytotoxic antibodies but indicated that the antibodies are directed against polymorphic antigenic determinants inherited in association with HL-A antigens. H-2 allo- and xenoantisera absorbed with human lymphoid cells and a panel of platelets bearing all the known HL-A specificities were still cytolytic when tested against murine lymphocytes, suggesting that only a small proportion of the heterogeneous population of H-2 antibodies react with human lymphocytes. On the other hand, HL-A alloantisera could be absorbed by lymphocytes from certain murine strains. These results suggest that the crossreactivity between human and murine lymphocytes is caused by antigens common to several HL-A (or H-2) types or by antigens linked to HL-A but not identical with them.     

Myasthenia Gravis,Autoantibodies, and HL-A Antigens

The serum of 100 patients with myasthenia gravis and 441 of their first-degree relatives was studied for the presence of autoantibodies against several antigens. Antibodies to skeletal muscle were present in 22% of the patients and in 2% of the relatives. Both these frequencies were significantly higher than those in matched control subjects. Also, antinuclear antibodies were present more often both in the patients and in the relatives. Typing for HL-A antigens had shown a positive correlation between HL-A 8 and myasthenia gravis which was significantly higher in women than in men. Antibodies to skeletal muscle and thymomas were found to be much rarer in HL-A 8-positive patients than in HL-A 8-negative patients; HL-A 8-positive patients acquired the disease at an earlier age.HL-A 2-positive patients more often had thymomas and antibodies to skeletal muscle than HL-A 2-negative patients; HL-A 2-positive patients acquired myasthenia gravis at a later age.The fact that the clinical aspects of the HL-A 8-negative and HL-A 2-positive patients were different from those of the HL-A 8-positive and HL-A 2-negative patients justifies the hypothesis that there are two forms of myasthenia gravis.     

Carbohydrate moieties of rat MHC class I antigens

The rat major histocompatibility complex class I antigens RT1.A^u and RT1.E^u from the u haplotype and RT1.Aⁿ from the n haplotype were labeled with ¹⁴C-asparagine or with ³H-fucose, mannose, galactose, and N-acetylglucosamine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed complete removal of radioactivity from the sugar-labeled antigen heavy chains by digestion with glycopeptidase F, an enzyme that removes N-linked glycans completely. High performance liquid chromatography analysis of the tryptic digests of the mixed sugar-labeled and asparagine-labeled antigens demonstrated that all the sugar-labeled peptides were coincident with asparagine-labeled peptides. The Aⁿ antigen showed three glycopeptides, each of which had different amounts of sugar radioactivity. The antigens A^u and E^u showed two glycopeptides with different amounts of radioactivity but at identical positions in the two antigens. Antigen E^u had an additional glycopeptide with a lower amount of radioactivity. The positions of the glycopeptides from the A^u and E^u antigens were different from those of the Aⁿ antigen. The peptide profiles of the ¹⁴C-asparagine-labeled A^u and E^u antigens demonstrated distinct differences between the molecules. The results of this study show that: (a) all the glycans on rat class I antigens are N-linked, as they are on H-2 and HLA class I antigens; (b) there are compositional differences among the glycans in each of the three antigens; (c) the glycosylation pattern of the rat class I antigens is similar to that of the mouse class I antigens, which contain two or three glycans, in contrast to that of the human class I antigens, which contain only one glycan; and (d) the antigens A^u and E^u from the same haplotype are more closely related to each other than they are to the Aⁿ antigen.     

Fate of HL-A antigens in aging cultured human diploid cell strains : II. Quantitative absorption studies

The expression of histocompatibility antigens on cultured human fibroblasts was studied utilizing a quantitative microabsorption assay. Trypsin treatment of cultured human embryonic and adult fibroblasts did not change their capacity to absorb selected HL-A alloantisera as compared with cells harvested by scraping. The density of HL-A antigens was found to remain unchanged throughout the finite in vitro lifetime of two human embryonic diploid cell strains (WI-38 and WI-26) and ten adult skin fibroblast cultures. Cultured fibroblasts derived from skin, lung, heart, and liver of one donor showed similar quantitative expression of HL-A1, 9, W5 and W16. These experiments support the contention that the HL-A marker system is at present the only system by which human fibroblasts derived from different normal human donors can be distinguished in vitro.     

The HL-A transplantation system

Summary The HL-A transplantation system is described in a survey. The nomenclature used by some investigators is compared. Two families serve as example for inheritance. The family data available concerning HL-A 2 are described. The importance of the HL-A antigens for grafts is shown, and a comparison with the mixed leucocyte culture is made.National Blood Group Reference Laboratory — WHO (Director: Prof. Dr. P. Speiser)     

Purification and characterization of HL-A antigens from human platelets, solubilized by the non-ionic detergent NP-40

Soluble HL-A antigens can be extracted with high yields from whole human platelets or platelet membrane preparations by the non-ionic detergent NP-40. The active molecules have high molecular weights ( 200 000) and the HL-A specificities present in the preparation were not separated by electrofocusing. An increase of the detergent/protein ratio gives rise to active molecules with lower molecular weight (15 000–30 000). In this case the two specificities studied (HL-A2 and HL-A7) could be separated by electrofocusing.     

Histocompatibility Antigens in Active Chronic Hepatitis and Primary Biliary Cirrhosis

The frequency of antigens HL-A 1 (48%) and HL-A 8 (52%) in 54 patients with active chronic hepatitis from south-east England was significantly higher than in 89 control subjects from the same region (22% and 17% respectively). No correlation could be detected with the age and sex of the patients or with the presence of a particular immunological abnormality but the frequency of HL-A 1 and HL-A 8 was much lower in the nine patients who were positive for HBAg than in the 45 HBAg-negative cases. These results provide further evidence of the importance of genetic factors in active chronic hepatitis. In contrast the frequency of HL-A 1 and HL-A 8 in primary biliary cirrhosis, both in 45 patients from south-east England and in 28 patients from western Scotland, was not significantly different from that found in control groups from the same regions.     

Isolation and characteristics of a rabbit β2-microglobulin: Comparison with human β2-microglobulin

A low molecular weight β₂-globulin has been isolated from urine of rabbits treated with sodium chromate. Several findings indicate that this protein is the rabbit counterpart of human β₂-microglobulin which is known to occur linked to the major histocompatibility (HL-A) antigens of man. The rabbit β₂-globulin and human β₂-microglobulin are very similar in amino acid composition, molecular size, molecular weight, electrophoretic mobility, and also in the presence of apparently analogous disulfide loops. More than half of the amino acids in the two proteins seem to be present in identical numbers. The urinary excretion of both proteins is increased by agents which induce renal tubular damage.     

Secondary response of in vitro-primed human lymphocytes to allogeneic cells

In vitro-primed human lymphocytes proliferate in a secondary mixed lymphocyte reaction (MLR) under the control of MLR-S specificities. HL-A antigens are unable to induce a secondary Proliferation. In familial haploidentical combinations, the secondary proliferation is specific for the priming MLR-S specificity, i.e., as early as 24 to 48 hours after the re-stimulation, a clearcut response is observed toward the sensitizing MLR-S specificity. The secondary response is reflected in acceleration of the reaction rather than in the peak of (³H) TdR uptake. However, when either haploidentical familial primed responding cells or unrelated cells primed toward MLR-S homozygous cells were used, no early typing response was observed against unrelated cells. The level of (³H) TdR incorporation toward cells which possessed and those which did not possess the priming specificity was identical until day 3–4. Noneless, the peak response toward cells possessing the priming MLR-S specificity occurs regularly 24 to 48 hours prior to the peak response toward the cells negative for the priming specificity (day 3–4 as opposed to day 5). Technical improvements are therefore needed before such a technique will provide a clearcut MLR-S typing methodology.     

Human platelets as a source of HL-A antigens : a study of various solubilization techniques.

The efficiency of various methods of solubilizing HL-A platelet antigens was investigated. The yield of soluble material was compared with that obtained from lymphocytes in culture in order to judge the quality of platelets as a source of HL-A antigens. The conclusion was reached that platelets, easily obtainable, can be considered as a good source of HL-A antigens.