Monoclonal anti-HLA-B27 antibody (B27M1): production and lack of detectable typing difference between patients with ankylosing spondylitis, Reiter's syndrome, and normal controls

Endogenous and exogenous factors contributing to the surface expression of HLA B27 on mutant APC

We have examined the expression of HLA B*2705 in the mutant cell line 721.220, which lacks endogenous HLA A and B alleles and expresses a defective tapasin molecule. Several peptide sensitive mAbs distinguish between HLA B*2705 expressed on the surface of 721.220 cells (B27.220) and 721.220 cells co-transfected with human tapasin (B27.220.hTsn). This differential staining defines subtle differences in the conformation of HLA B27, which most likely reflect changes in the repertoire of antigenic peptides bound to B27 in the presence and absence of wild type tapasin. HLA B27 molecules expressed on the surface of 721.220 display increased levels of "free" B27 heavy chain (HC-10 staining), an epitope that is dependent on TAP-translocated peptides. The conformation and stability of B27 molecules was examined by investigating the integrity of mAb epitopes and the half-lives of these complexes on cells cultured with and without serum. The decay of surface B27 epitopes occurred more rapidly in B27.220 and this effect was exaggerated in serum free media. Importantly, the decay of surface B27 molecules in B27.220.hTsn cells was characterized by an early increase in HC-10 staining when the cells were grown in serum free media. This decay of B27 molecules via HC-10 reactive intermediates was not observed in B27.220 cells, implying molecules on these cells may already have passed through this stage prior to surface expression. Taken together these observations indicate that tapasin has a significant contribution to the composition and stability of the B27-bound peptide repertoire.

HLA-B27-restricted antigen presentation in the absence of tapasin reveals polymorphism in mechanisms of HLA class I peptide loading

Tapasin is a resident ER protein believed to be critical for antigen presentation by HLA class I molecules. We demonstrate that allelic variation in MHC class I molecules influences their dependence on tapasin for peptide loading and antigen presentation. HLA-B*2705 molecules achieve high levels of surface expression and present specific viral peptides in the absence of tapasin. In contrast, HLA-B*4402 molecules are highly dependent upon human tapasin for these functions, while HLA-B8 molecules are intermediate in this regard. Significantly, HLA-B*2705 like HLA-B*4402, requires tapasin to associate efficiently with TAP (transporters associated with antigen processing). The unusual ability of HLA-B*2705 to form peptide complexes without associating with TAP or tapasin confers flexibility in the repertoire of peptides presented by this molecule. We speculate that these properties might contribute to the role of HLA-B27 in conferring susceptibility to inflammatory spondyloarthropathies.

Yersinia enterocolitica serotype O:3 alters the expression of serologic HLA-B27 epitopes on human monocytes

The expression of serologic HLA-B27 epitopes on leukocytes of patients with reactive arthritis or ankylosing spondylitis has been shown to be modified in the course of the disease. The purpose of this work was to study whether phagocytosis of arthritis-triggering microbes in vitro alters the expression of HLA-B27 molecules on human antigen-presenting cells and to characterize the underlying mechanisms. Human monocytes and HLA-B27- or HLA-A2-transfected human U-937 cells were exposed to Yersinia enterocolitica serotype O:3. The expression of different epitopes of HLA-B27 was monitored by using immunofluorescence, and their synthesis was determined by quantitative immunoprecipitation. Our results show that phagocytosis of Y. enterocolitica serotype O:3 changed the expression of serological HLA-B27 epitopes. This was due to the reduced synthesis of HLA-B27 molecules. The expression of especially the epitopes which depend on the presence of peptides in the antigen-binding groove was changed. The expression of the ME1 epitope, which has been shown to be important for T-cell recognition in patients with reactive arthritis, was decreased. Down-regulation of epitopes important for the T-cell recognition may impair the elimination of arthritis-triggering microbes and lead to persistent infection. In addition, Y. enterocolitica serotype O:3 seemed to alter the repertoire of peptides presented by the HLA-B27 molecules on human monocytes. This may have a role in the pathogenesis of reactive arthritis via an autoimmune mechanism.

Molecular mimicry: any role in the pathogenesis of spondyloarthropathies?

Ankylosing spondylitis and reactive arthritis are seronegative spondyloarthropathies, which are strongly associated with HLA-B27. Despite intensive investigation, the basis for this association is not clear. However, in recent years one favored hypothesis to explain this linkage has been that of molecular mimicry, i.e., sharing of linear or conformational epitopes common to microbial antigens and host structures. During the past few years several examples of molecular mimicry between HLA-B27 and microbial antigens have been described. Heat shock proteins, among others, have been considered as target candidates for autoimmune phenomena, because of the high degree of homology between bacterial and mammalian species. Reactive arthritis triggered by Yersinia or Salmonella provides a unique model for studying the pathogenetic mechanisms underlying human inflammatory joint diseases in general, because the arthritogenic microbes are known and well-characterized. We have described two bacterial proteins that share amino acid homology with HLA-B27, namely YadA (Yersinia adhesin) and OmpH, outer surface proteins of Yersinia and Salmonella, respectively. Notably, the area of identity of these amino acid sequences is located in the same place on the HLA-B27 molecule as a hexapeptide identical between Klebsiella nitrogenase and HLA-B27, and a pentapeptide shared by a Shigella flexneri protein and HLA-B27. We have investigated immune responses to a panel of synthetic peptides based on the HLA-B27-homologous portions of pathogen-specific antigens in patients with reactive arthritis and ankylosing spondylitis. One third of the patients have antibodies to the synthetic peptides. However, instead of recognizing the HLA-B27-homologous portion, the antibodies are directed against the flanking sequences of the synthetic peptides. The concept of the role of molecular mimicry between HLA-B27 and microbial antigens in the pathogenesis of spondyloarthropathies is discussed, with a conclusion that no convincing evidence for its significance exists at the present.

HLA-B27 subtypes in the spondarthropathies

The spondarthropathy (Sp)-associated HLA-B27 antigen includes at least seven subtypes, B*2701-07, of which 01, 02, 05 and 07 occur in Caucasians. This study examined the B27 subtype distribution in British patients with Sp. The 133 HLA-B27+ subjects comprised 94 European Caucasian Sp (58 ankylosing spondylitis (AS), 22 reactive arthritis (ReA; 11 sexually acquired (SARA), 11 enteric (EReA)), eight undifferentiated Sp (USp), and six pauciarticular juvenile-onset chronic arthritis (pJCA)) patients, and 34 healthy Caucasian controls, together with four Asian Indian and one Chinese. 35S-labelled B27 was immunoprecipitated with anti-B27 MoAbs, and subtyped according to isoelectric point (pI) following isoelectric focussing. The use of B27 MoAb permitted subtype assignment without full class I HLA typing. The vast majority (95%) were B*2705 (Caucasian controls 31/34; AS 55/58; ReA 21/22; USp 8/8, and pJCA 6/6; Indian control 1/1 and AS 2/3; Chinese pJCA 1/1), and the remainder B*2702. No B*2701 or 07 subjects were identified. AS occurs in both B*2702 and 05 subjects, and we extend this observation to small numbers of ReA and of Indian AS subjects. This implicates molecular features shared between B27 subtypes, rather than subtype-determining regions of the antigen, in Sp pathogenesis.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.

Crystallization and preliminary X-ray diffraction studies of the human major histocompatibility antigen HLA-B27

The class I major histocompatibility (MHC) antigen HLA-B27 was purified by immunoaffinity chromatography from the homozygous human B lymphoblastoid cell line LG-2. Detergent-soluble HLA-B27 was cleaved with the protease papain to remove the hydrophobic transmembrane region and the cytoplasmic tail. Crystals of the resulting water-soluble extracellular fragments were obtained in hanging drops by the vapor-diffusion method. The crystals are triclinic, space group P1, with unit cell dimensions a = 45.9 A, b = 71.0 A, c = 83.7 A, alpha = 79.4 degrees, beta = 88.5 degrees, gamma = 89.9 degrees, and diffract beyond 2.5 A resolution.

Transfection of HLA genes using genomic DNA

Mouse L cells expressing HLA genes are potentially useful for producing and analyzing monoclonal antibodies (mAb) to HLA molecules. This paper describes the preparation of transfectants using uncloned human DNA and three methods to isolate the HLA-expressing transfectants. Transfectant libraries were made by cotransfecting mouse thymidine kinase (tk)-deficient L cells with a calcium phosphate precipitate containing genomic DNA and tk plasmid DNA. Transfectants expressing HLA genes were isolated using these methods: immunomagnetism, replicate-plating combined with cellular enzyme-linked immunoassay, and sorting using a fluorescence-activated cell sorter. Two HLA-A2 transfectant were isolated using immunomagnetism, two HLA-A24 transfectants by replicate plating, and one HLA-Bw60 transfectant by FACS. However, no transfectants were isolated that stably expressed class II genes. The class I transfectants have been useful in characterizing several locally prepared mAbs which bind to monomorphic determinants on class I HLA molecules. Two of the transfectant lines, one expressing HLA-A2 (8001) and the other HLA-A24 (8008), have been included in the collection of lines distributed for use in the Eleventh International Histocompatibility Workshop.

Antigenicity of HLA-A2 and HLA-B7. Loss and gain of serologic determinants induced by site-specific mutagenesis at residues 62 to 80

The contribution of the hypervariable region spanning amino acid residues 62 to 80 to the serologic determinants of HLA-A2 and HLA-B7 has been examined by site-directed mutagenesis. Three HLA-A2 mutants, having changes as in HLA-B7 at positions 62, 76, and at the complete 65-to-80 segment, respectively, were obtained and expressed on class I HLA-deficient human cells upon transfection. The reactivity of 19 monoclonal antibodies (mAbs) against both broad public and allospecific determinants on HLA-A2 and HLA-B7 was analyzed. The results indicate that: (1) the change at residue 62 abrogated recognition of the corresponding HLA-A2 mutant by mAb MA2.1 (anti-A2 + B17); (2) the change at residue 76 did not effect any of the determinants analyzed, although its side chain is easily accessible at the surface of the molecule; (3) the replacement of the whole 65-to-80 segment in HLA-A2 by that from HLA-B7 abrogated recognition by MA2.1 and by 108-2C5, a mAb recognizing a public determinant from the HLA-A locus. Such replacement led to gaining the determinants recognized by mAbs GS145.2 (anti-B7 + B27) and SFR8-B6 (anti-Bw6); and (4) the HLA-A2-reactive mAbs whose reactivity was known to be abrogated by changes in alpha 2 were unaffected by the changes introduced in alpha 1, underlining the frequent segregation of serologic determinants on class I antigens to single domains.

Generation of a human hybridoma producing a pure anti-HLA-A2 monoclonal antibody

We report the production and characterization of a human monoclonal IgM hybridoma antibody recognizing antigen HLA-A2. B lymphocytes obtained from the peripheral blood of a multiparous volunteer 1 week postpartum were transformed in vitro by Epstein-Barr virus, screened by a microlymphocytotoxicity assay, and electrofused with the heterohybridoma fusion partner, K6H6/B5. A specifically anti-A2 secreting hybridoma cell line. MBW1, was then identified and cloned. The cytotoxic IgM antibody produced showed complete correlation (r = 1.00) with the A2 antigen on a large panel of unrelated donors' lymphocytes, and no cross-reactivity with A28, Aw68, or Aw69 antigens was observed.

Effect of a free sulphydryl group on expression of HLA-B27 specificity

Sequence studies indicate that the alpha-1 domain of the HLA-B27 molecule has a characteristic unpaired cysteine residue at position 67, adjacent, because of secondary structure, to a lysine at position 70. Simple chemical considerations predict that this cysteine should have an exceptionally reactive sulphydryl group. We have shown by ELISA and flow cytometry that the binding of some monoclonal antibodies to B27 on lymphoid cell lines can be inhibited by reagents which react with sulphydryl groups. However this inhibition is never complete: the evidence suggests 2 forms of B27 molecule, one of which is already blocked. We propose that some HLA molecules with oxidised sulphydryls are recognised as different from the reduced forms. Whether they are also recognised as foreign will depend on an individual's history of thymic learning. Oxidation to 'foreign' HLA in the adult is likely to predispose to inflammatory reactions.

The use of enzyme immunoassay (EIA) and radiobinding assay to investigate the cross-reactivity of Klebsiella antigens and HLA B27 in ankylosing spondylitis patients and healthy controls

The binding of rabbit anti-Klebsiella antibodies to tissue-typed lymphocytes obtained from 30 ankylosing spondylitis (AS) patients and 54 healthy subjects has been measured by an enzyme immunoassay method. HLA B27 positive lymphocytes obtained from either AS patients (t = 3.60; p less than 0.001) or healthy subjects (t = 3.77; p less than 0.001) were found to bind Klebsiella antibodies to a significantly greater extent than non-B27 lymphocytes obtained from healthy controls. Absorption studies demonstrated that HLA B27 positive lymphocytes absorbed out significantly more anti-Klebsiella antibodies than HLA B27-negative lymphocytes (t = 6.76; p less than 0.005). These results are compatible with cross-reactivity or molecular mimicry between HLA B27 and epitopes on some Gram-negative bacteria such as Klebsiella.

Reactivity between monoclonal anti-HLA-B27 antibodies and bacterial components: is there a consensus of findings?

Studies addressing the molecular aspects of the postulated cross-reactivity between the HLA-B27 antigens and the bacteria known to precipitate arthritis (e.g., Shigella, Salmonella, Yersinia and Campylobacter) are reviewed. In conclusion, the necessity for further research into the pathogenesis of arthritis is stressed.

HLA expression and function in single and double HLA-B27-transgenic mice

The expression and function of HLA antigens in mice single transgenic for HLA-B27.2 (sTGM-B27.2) or double transgenic (dTGM) for HLA-B27.2 and human beta 2-microglobulin (h beta 2m) were compared. B27.2 could be well detected on the cell membrane of lymphocytes of sTGM. However, the expression in sTGM was much lower than in dTGM mice. Nevertheless, also in sTGM mice, the B27-transgene product possessed all functional properties of a class I HLA molecule. This was shown by the recognition and induction of antibodies and cytotoxic T cells, by the induction of "allo"-immunity, including skin graft rejection, and by the ability to present viral antigens. In dTGM, the expression of B27 on peripheral blood lymphocytes, spleen and lymphnode cells was comparable to H-2. However, on thymocytes, a relatively lower expression of HLA than H-2 was observed. This low expression of B27 on thymocytes is in concert with the observation that B27 is expressed only in the medulla of the thymus and not detectable in the cortex.

Expression and immunogenicity of HLA-B27 in high-transfection recipient P815: a new method to induce monoclonal antibodies directed against HLA-B27

The immunization of a (BALB/c x C57BL/6) FI mouse with murine transfectants expressing the HLA-B27 antigen resulted in a panel of polymorphic monoclonal antibodies with specificity for HLA-B27 and some additional HLA-antigens. Specificity of the antibodies was defined by cytofluorometric analysis on a panel of lymphoblastoid cell lines (LCL) derived from HLA typed individuals. Three of these antibodies are cytotoxic, and one of them inhibits B27-specific T cell cytotoxicity. Our results indicate that HLA-class I transfectants could be used to generate polymorphic antibodies, and that these antibodies may be helpful for HLA typing and for definition of epitopes recognized by T cells.

Genetics of the spondarthropathies

Recent investigation of the possible role of bacteria in the pathogenesis of AS has provided very interesting data. What is at present lacking is a clear demonstration that the findings point to the actual mechanisms involved in the initiation of the disorder. Rapid progress in three related areas of research gives hope that, in the relatively near future, the genetic basis for susceptibility to AS will be elucidated. These are the demonstration of the detailed structure of an HLA class I molecule, of the primary amino acid structure of B27 heavy chain with its subtypes, and of the nature of the interaction between foreign proteins and MHC molecules which leads to antibody and cytotoxic cell responses. It is just possible that the B27 molecules have a disease-promoting capability because of some structural characteristic independent of their antigen binding site. However, it may perhaps be considered more likely that it is the propensity of the specific antigen-binding site itself to bind to a particular group of antigenic peptides that will explain the susceptibility of B27-positive individuals to several clinical disorders. The ability to study the properties of antigenic epitopes which preferentially bind to the very variable binding site of different MHC molecules raises the possibility of revealing the antigenic structures which bind to B27 molecules in patients with AS. This could in turn lead to the source of these antigens in the environment. There has been a tendency to assume that one simple model will explain all the B27-associated disorders but it may be preferable to keep an open mind about the possibility that the mechanisms involved in AS, in the bacteria-induced acute arthropathies and in acute anterior uveitis may not be identical. At the same time, there is a need to continue further direct investigation of the role of microbiological agents in AS both in vitro and in vivo, as ultimately it is most likely that, by blocking the effects of such agents as may be shown to be involved, progress in our ability to influence the progress of the disease in a fundamental way will be achieved. There is still little information as to how the tissues involved in AS come to be the particular targets of the pathological process and currently proposed theories of pathogenesis have not yet provided very satisfactory answers to this problem.

Four cytotoxic human-human hybridoma antibodies that react with HLA-B27

PBMC were isolated from a multiparous woman with HLA-B27 specific Abs in her serum. The HLA type of the donor was A2,9:B7. The PBMC were EBV transformed, and four cell lines making cytotoxic Abs to HLA-B27+ cells prepared. Hybridomas were constructed by fusing the EBV lines with the human fusion partner KR4. All four mAbs were of IgM isotype. One mAb (TrBH12) reacted specifically with B27+, B37+ and Bw47+ lymphoblastoid cell lines and with all B27+ PBMC except for a rare variant so far found only in one Norwegian family. Another mAb (Tr3B6) was cytotoxic for all B27+ cells tested, including the TrBH12- variant; in addition, it showed weaker cross-reactions to Bw42, B49 and a cell line with the probable phenotype B7,38. Supernatant from the Tr3B6 hybridoma was tested in lymphocytotoxicity against a panel of 658 individuals, 141 of whom were B27+. With this panel, Tr3B6 showed perfect correlation with HLA-B27. The two last mAbs (TrCG10 and TrBF1) reacted with all B27+ cells tested, but in addition showed quite extensive cross-reactions.

Postdysenteric reactive arthritis. A clinical and immunogenetic study following an outbreak of salmonellosis

Following an outbreak of foodborne gastroenteritis caused by Salmonella typhimurium, questionnaires were sent to affected individuals and then to the family physicians of any who experienced extra-enteric complications. Of 260 individuals infected with S typhimurium for whom adequate data were obtained, 19 patients developed joint disease (7.3%). All were men; the mean age +/- SD was 39.3 +/- 1.6 years. Among the 16 patients for whom this information was available, the interval from the onset of diarrhea to the onset of joint pain was less than 7 days in 7, 8-21 days in 2, and greater than 21 days in 7. There was a significantly longer duration of diarrhea in those patients with joint disease (mean +/- SEM 15.2 +/- 2.6 days) than in those without complications (10.0 +/- 1.1 days) (P less than 0.01). The joint disease was monarticular in 3 patients and polyarticular in 16. The joints most commonly affected were the elbow (47%), wrist (47%), knee (42%), low back (32%), and shoulder (32%). Six of the 19 patients had at least 1 extraarticular feature: ocular (5 patients), mucosal (1 patient), urethral (2 patients), or cutaneous (1 patient). Of these 19 patients, 11 were located and agreed to HLA typing. Four were positive for HLA-B27, 6 were HLA-B7 positive, and 1 had HLA-Bw60. Of the 4 B27 positive patients, 3 were DR1 positive; of the 6 B7 positive patients, 5 were DR2 positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-HLA-B7,B27,Bw42,Bw54,Bw55,Bw56, Bw67,Bw73 monoclonal antibodies: specificity, idiotypes, and application for a double determinant immunoassay

The monoclonal antibodies (MoAbs) KS3 and KS4 are secreted by hybridomas constructed with splenocytes from a BALB/c mouse sequentially immunized with the cultured lymphoid cells JKu and LG-2 which share only the HLA-B27 specificity. Serologic and immunochemical assays have shown that the two MoAbs recognize the same (or spatially close) determinant expressed by HLA-B7,B27,Bw42,Bw54,Bw55,Bw56,Bw67, and Bw73 alloantigens. This determinant is spatially close but distinct from those defined by the anti HLA-B27 monoclonal antibodies described in the literature. The syngeneic antiidiotypic MoAb T12-105 and T12-211 elicited with MoAb KS4 were shown to recognize idiotopes within the antigen combining site of MoAb KS3 and KS4. Neither idiotope was detected on the anti HLA class I and anti HLA class II monoclonal antibodies tested. The MoAb KS4 in combination with the anti human beta 2-microglobulin MoAb NAMB-1 was utilized to develop a double determinant immunoassay (DDIA). The latter represents a sensitive method to detect and quantitate HLA-B27 antigens in spent culture medium of lymphoid cell lines and in serum. Typing for HLA-B27 antigens with the DDIA of sera from HLA typed donors yielded results highly correlated with those of the conventional lymphocytotoxicity assay.

A common epitope between HLA-B27, -B13 and -B37 alloantigens defined by a monoclonal antibody

An anti-HLA-B27 monoclonal antibody produced by the hybridoma technique is described. This BD.7 reagent is a cytotoxic IgM antibody. Its reactivity was studied by lymphocytotoxicity tests, indirect immunofluorescence tests and biochemical analysis against an extensive panel of peripheral blood mononuclear cells. All HLA-B27 positive samples, either from normal subjects or from patients with Ankylosing Spondylitis, were recognized by this reagent. Moreover, a cross-reaction was observed with HLA-B13 cells, and a new unexpected reaction with all HLA-B37 cell suspensions. The interest of such a reagent is discussed.

A double determinant immunoassay for HLA class I typing using serum as an antigen source

We have applied a double determinant immunoassay (DDIA) to HLA-A2,A28, and B13 typing, using serum as an antigen source. The results obtained show a correlation of 96% (B13) and 89.1% (A2,A28) with the results obtained by conventional HLA typing. Furthermore, the results obtained were highly reproducible, since testing of 18 sera on two occasions gave concordant results with all samples tested. The variation in the content of HLA-A2 antigens in sera taken at different times from a given donor was less than 5%. A sevenfold variation was found in the serum level of HLA-A2,A28 antigens: the highest level was found in the sera from HLA-A2,A28 donors and in decreasing order in HLA-A2 homozygous, HLA-A28 homozygous, HLA-A2 heterozygous, and HLA-A28 heterozygous donors. The results of this study indicate that the DDIA is a sensitive, simple, and reproducible procedure for HLA class I typing. The DDIA offers the following advantages in comparison with the conventional lymphocytotoxic assay: it provides information not only about the expression of a given alloantigen, but also about its level; it does not require viable cells, thus facilitating retrospective studies and typing of leucopenic patients; it eliminates variability of results caused by abnormal susceptibility of target cells to complement-dependent lysis.

A monoclonal antibody against HLA-A11 and A24

A monoclonal IgG antibody was produced from a mouse immunized with an A11, A24; B27, B44 Epstein-Barr virus transformed B lymphoblastoid cell line. The antibody, A11.1M, by standard lymphocytotoxicity assay, reacts with all cells expressing HLA-A11 and -A24. Absorption studies with both A11+, A24- and A11-, A24+ platelets removed antibody reactivity against A11 and A24 lymphocytes. The shared antigenic determinant between A11 and A24, as defined by this antibody, A11.1M, represents a new "supertypic" determinant.

HLA-antigens in the human uvea

With the use of monoclonal antibodies in an indirect immunofluorescence technique we studied the distribution of Class I (HLA-ABC and B27) and Class II (HLA-DR) antigens in the human uvea. W6/32, directed against the core of HLA-ABC antigens, was used to study the distribution of Class I antigens. The anterior border layer of the iris, the non-pigmented and pigmented epithelium and the external basement membrane of the ciliary body and the vascular endothelium in the uvea showed a positive staining for Class I antigens. B27/M1, directed against an epitope of the HLA-B27 antigen, and the control antibody A11/Aw24, which was directed against an epitope of HLA-A11, revealed the same distribution pattern in respectively HLA-B27 and HLA-A11 positive donor eyes. The intensity of their staining was much weaker than the staining with W6/32. Class II antigens were studied with OkIa1, an antibody directed against the core of HLA-DR antigens. HLA-DR antigens were detectable on single cells scattered throughout the entire uvea. These cells did not seem to relate to any anatomical entity. No staining for Class II antigens was seen in the uveal blood vessel endothelium. The expression of HLA-antigens in the uvea is compatible with the distribution in other tissues. These findings suggest that the expression of HLA-B27 in the human uvea does not explain why the eye is one of the target tissues in HLA-B27 associated disease.

Further studies on the epitopes of HLA-B7 defined by murine monoclonal antibodies

Monoclonal antibodies reactive with polymorphic epitopes of HLA-B7 were analyzed by direct and indirect cytotoxicity assays on established panels of HLA typed lymphocytes. This permitted further refinement of their specificity and the identification of various novel reactions. The topographic relationship of polymorphic epitopes on the surface of the B7 molecule was assessed with various serological assays using cell surface B7 or papain solubilized B7 as the antigenic target. These studies focused on monoclonal antibodies recognizing B27 and B7. The results, in combination with those of previously published studies, are used to provide a current assessment of the epitope map of HLA-B7 as defined with mouse monoclonal antibodies. This is compared to the results obtained with alloantisera.

Six variants of HLA-B27 identified by isoelectric focusing

Six variant forms of HLA-B27 were identified among 68 unrelated B27-positive donors by isoelectric focusing (IEF) gel analysis. Each of the six IEF variants was distinguished by charge heterogeneity of desialated B27 heavy chains immunoprecipitated with specific monoclonal antibody (MAb). Charge differences varied from single to several charge units, indicating that these variants may have substantially different amino acid compositions. Informative family study showed that three B27 variant molecules were genetically determined. The uniqueness of these variant molecules was also demonstrable using a panel of alloantisera and MAbs recognizing B27-associated epitopes. Six distinct serological reactivity patterns were observed. Five of these serological patterns correlated with four of the IEF-defined variants, two of these patterns being associated with one IEF variant form. The sixth serological pattern was shared by the remaining two IEF variants. Combining the results of the electrophoretic and serological analyses, it is apparent that there are more than six structural variants within the B27 alloantigen family. Some B27 variant forms were found only in individuals of particular racial origin, indicating that unique genetic variations might occur in different racial groups. In a preliminary analysis of patients with ankylosing spondylitis, no apparent correlation was observed between any specific B27 variants and disease susceptibility.

Molecular variants of the HLA-B27 antigen in healthy individuals and patients with spondylarthropathies

Despite major advances in genetic and structural studies of the HLA-B27 antigen, the underlying mechanism responsible for the remarkable association between this antigen and spondylarthropathies remains unknown. At a molecular level, the use of B27M1 and B27M2 monoclonal antibodies has permitted the identification of distinct allospecific epitopes on the B27 molecule. One of these epitopes, B27M2, is polymorphic and has allowed us to define B27 variants: B27M2[+], B27M2[-], and B27M2[int]. The heterogeneity of the B27 antigen correlates well with biochemical and cytotoxic evidence of genetic heterogeneity. These variants exhibit ethnic variation and also appear to correlate, in preliminary studies, with disease susceptibility, especially among Orientals. HLA gene probing is potentially an even more precise tool than monoclonal antibodies for the study of MHC-related disease susceptibilities. Initial work in our laboratory has resulted in the production of probes with specificity for HLA-B locus genes and current efforts are directed toward the derivation of B27 allele-specific probes. It seems likely that, when such probes are applied to B27-positive individuals, complexity in addition to the B27M2 variants will be revealed. Yet to be defined is the mechanism behind the association between B27 and AS. Is the association causal for disease, or is B27 indeed just a marker for other pathogenic factors somehow linked to it? Available evidence points to both causal and linked roles for B27 in ankylosing spondylitis. Products of both HLA and non-HLA gene families may interact with infectious disease pathogens in susceptible individuals to produce a disorder which may not be specific in its association with any one pathogenic factor.

A monoclonal antibody recognizing a determinant shared by HLA-A2 and HLA-Aw69 (A28* variant)

A cytotoxic murine monoclonal antibody, designated P5.1, was tested against 613 unrelated donors and found to react with 401 who were positive for HLA-A2 (sensitivity = 100%) and with 8 of 82 positive for HLA-A28. The latter split of A28 corresponds to the "A28* variant" that in the Ninth International Histocompatibility Workshop (9WS) was designated Aw69(28*). The epitope recognized by antibody P5.1 is distinct from the alloantisera-defined determinants that characterize HLA-A2 and A28. Immunoprecipitation of specific antigens with selected monoclonal antibodies and isoelectric focusing gel electrophoresis demonstrated that A2, Aw68(28) and Aw69(28*) are distinct polypeptides. Thus, the A2-A28 antigen family consists of at least three different alleles definable using alloantiserums specific for A2 and A28, and monoclonal antibodies such as P5.1 recognizing the A2,Aw-69(28*)-epitope.

Klebsiella 'modifying factor': binding studies with HLA-B27+ and B27- lymphocytes

On the basis that extracts of some klebsiella organisms bind selectively to the lymphocytes of HLA-B27+ individuals and induce the appearance of new antigens, attempts were made to detect the binding of klebsiella products to HLA-B27+ and B27- lymphocytes by a number of different techniques. Firstly, blocking of the binding of two different HLA-B27 specific monoclonal antibodies to HLA-B27+ lymphocytes has been examined following exposure of the lymphocytes to a cell-free culture filtrate from K. pneumoniae K21 and K43. There was no reduction in the cytotoxicity of either antibody, suggesting that neither of the epitopes detected by the anti-HLA-B27 monoclonal antibodies is a binding site for klebsiella products. Secondly, we have studied the binding of partially purified, radiolabelled klebsiella products to healthy HLA-B27+ and B27- lymphocytes. There was no significant difference either in terms of numerical counts bound or by comparing, by SDS-PAGE analysis, the molecules bound to each cell type. At the level of sensitivities of these techniques we can detect no difference in binding of klebsiella products to the lymphocytes of healthy HLA-B27+ and B27- individuals.

HLA loss variants of a B27+ lymphoblastoid cell line: genetic and cellular characterization

Variants of a lymphoblastoid cell line, LCL 526 (SB3 MB1 DR1 B44 C5 A2/SB4 MT4 DR4 B27 C2 A24), which lost various HLA specificities were selected with monoclonal antibodies and complement using a method developed by Kavathas et al. (PNAS 77:4251, 1980). Using alpha B27 monoclonals, 8 B27 only loss mutants and 4 B27 haplotype multiple loss mutants were generated. The parental LCL 526 and two of the B27- mutants were used to select alpha B27 CTLs. The selection of six A2 loss, one A2-C5 loss, and 14 A2 haplotype multiple loss variants as well as secondary selection on haplotype loss variants to obtain A null, B null, DR null, and total A, B, C, null variants is also described. The usefulness of these mutants for the study of the relationship between B27 and disease and as two new haplotypes for immunologic, genetic, and molecular research is discussed. These mutants are available to other researchers.

Recognition by a murine monoclonal antibody of a unique epitope specific for the human alloantigen HLA-B8

A cytotoxic murine monoclonal antibody recognizing a specific HLA alloantigen was produced from the spleen cells of a BALB/c immunized with partially purified class I glycoproteins from an HLA-A1,B8 homozygous B-lymphoblastoid cell line. The antibody, designated P8.1, was tested against cells from 521 unrelated donors. It reacted with each of the 83 donors known to be HLA-B8 positive and with no HLA-B8 negative donors (sensitivity, 100%; specificity, 100%). Immunoprecipitation with antibody P8.1 and polyacrylamide gel electrophoresis confirmed that the antigen recognized was a class I structure. Although most murine monoclonal anti-HLA antibodies previously described have recognized "public" or supertypic specificities, the identification of a monoclonal antibody specific for a "private" HLA alloantigen indicates first that the BALB/c mouse has the appropriate immune response repertoire for recognizing certain HLA allospecificities and second that HLA-B8 can be defined by a single unique epitope.

A cytolytic human T lymphocyte clone differentially recognizing HLA-B27 subtypes

A cytolytic human T cell (CTL) clone, designated F/M-F159, has been produced, the lytic specificity of which distinguishes subtypes of HLA-B27. This was demonstrated in cell-mediated lympholysis (CML) assays of: 1) a panel of target cells from unrelated donors, 75 B27 + and 36 B27-; 2) six families, including 20 B27 + and 14 B27- individuals; and 3) B27 + and B27- variants of a B27+ lymphoblastoid cell line (LCL). Specificity of F/M-F159 for HLA-B27 was confirmed by blocking studies with monoclonal antibodies. Lysis of B27 + targets reactive with the anti-B27 monoclonal antibody B27M2 was 30-104%, while lysis of B27 +, B27M2- targets was 4-22%. Lysis of B27- targets expressing HLA-Bw47, known to be cross-reactive with the B27M2 antibody, was 10 to 19%, while lysis of all other B27- targets was less than or equal to 10%. Clone F/M-F159 lysed B27 + targets, and failed to lyse B27- targets, irrespective of the clinical status of the cell donors. It is concluded that F/M-F159 recognizes an epitope present on the majority of serologically identified HLA-B27 molecules and that this epitope is closely related to, but not identical with, the epitope recognized by the antibody B27M2. These findings are interpreted as supporting a direct role for HLA-B27 in disease pathogenesis.

Anti-HLA-A2 and -A28 monoclonal antibody: production and study of the cross-reaction

An anti-HLA-A2 and -A28 monoclonal antibody, XV.17, has been prepared by immunizing a Balb/c mouse with PBL. This XV.17 monoclonal antibody is a cytotoxic IgM. Its reactivity was tested by lymphocytotoxicity test and indirect immunofluorescence technique, in parallel with an alloantiserum ORA having the same anti-HLA-A2, -A28 reactivity pattern, against different panels. Family studies were undertaken. Absorptions-elutions and cytofluorometry experiments were performed to study the cross-reaction. The XV.17 monoclonal antibody is cytotoxic against all the HLA-A2 and -A28 tested cells, and is absorbed by HLA-Aw23 and -Aw24 cell suspensions.

A cloned cytotoxic T-lymphocyte (CTL) line recognizing a subtype of HLA B27

The lymphoblastoid cell-line JY (HLA-A2,2;B7,7;C-; DR4,w6) was used to stimulate T cells from donor HG (HLA-A2,w23; B40,w44; Cw4; DRw6,7). Cloned CTL line were obtained by limiting dilution after tertiary stimulation. Strong cytotoxic activity on stimulator cells was found with all CTL clones obtained. One of the clones (HG-31 recognized a subtype of the HLA-B7 antigen. In this paper, we describe another long-term cloned CTL line (HG-61). This line, when tested on a panel of 107 target cells from unrelated individuals, recognized a subtype of HLA-B27 (B27 "K"). There was no significant association with any other HLA antigen. The cloned CTLs were T8+ and their cytotoxic activity could be blocked by the monoclonal antibody W6/32 which recognizes a framework determinant on HLA-A, -B, and -C molecules. In families, reactivity with cells of the CTL line (HG-61) segregated with HLA. It is concluded that the CTL line interacts with an antigenic determinant shared between the HLA-B7 antigen and JY and the subtype of HLA-B27 (B27 "K"), or detects products of a gene closely linked to HLA-B, not revealed by present-day serology.

A new polymorphic determinant distinct from but expressed concomitantly with an HLA-Bw44 specificity

A new antigenic determinant defined by a monoclonal antibody (6.7) is described which displays restricted expression being present only on the cells of the immunizing donor and his father and not on a panel of over one hundred unrelated HLA-typed cells. The determinant segregated with the HLA haplotypes of the immunizing donor's family and was shown by immunochemical and capping studies to be located on a subpopulation of HLA molecules. Further capping and antibody-blocking studies using HLA-typing alloantisera revealed that the 6.7-reactive determinant was located on the same molecules that expressed the HLA-Bw44 specificity but was a separate epitope to the polymorphic HLA specificity.

HLA and disease

This review describes the greater portion of a large number of new studies on HLA and disease association which has appeared in the literature since 1979. The majority of these are concerned with the association of certain diseases with class II major histocompatibility complex antigens. The possible biologic significance of these associations in terms of their probable etiology appears to be the prevailing theme. Current thinking regarding certain heritable diseases is described. It seems that although much has been done to resolve the genetics of insulin-dependent diabetes mellitus, other diseases such a multiple sclerosis still remain a mystery. Doubtlessly, much will be gained from DNA cloning and sequencing studies proposed for the future. A great deal of new information has been obtained relative to HLA itself. New loci have been postulated in the HLA-D/DR region through the use of powerful immunochemical procedures made possibly by the advent of modern technological advances. The impact of these developments on our understanding of the function of the MHC in man and its possible relationship to disease are discussed.

Identification of several functional subgroups of HLA-B27 by restriction of the activity of antiviral T killer lymphocytes

Anti-Epstein-Barr virus and antiinfluenza A cytotoxic T lymphocytes (CTL) have been used to study the restriction of human antiviral responses by HLA-B27 antigens. Three functional subgroups of HLA-B27 have been clearly distinguished by this "restriction-typing assay". No cross-reaction could be detected between the three subgroups either at the CTL level or at the level of antigen-presenting cells. The cells of subgroup 1 are always positive [M2(+)] when tested in immunofluorescence with a monoclonal B27-specific antibody which divides HLA-B27 into a major M2(+) and a minor M2(-) subgroup. These M2(+) group 1 cells are apparently also HLA-B27W as previously shown by Ivanyi and co-workers using anti-HLA-CTL. Subgroup 2 includes only M2(-) cells. A comparison between this group and the previously described HLA-B27K is not fully conclusive, since two typing cells which were clearly HLA-B27K apparently did not belong to group 2. Only two donors, both of Oriental origin, have been included in subgroup 3. Both of them were "M2 intermediate". These results demonstrate (1) the existence of several functional subgroups of HLA-B27 with an interesting correlation with the M2(+), M2(-), or M2 intermediate phenotypes, and (2) the possibility of using the restriction-typing assay to define such functional subgroups not detected by classical allosera.

Two monoclonal antibodies detecting allotypic determinants of HLA-A

Three mouse hybridomas producing cytotoxic antibodies against HLA were established. By standard microcytotoxicity test against panels of normal controls, the antigen defined by MA-9 antibody (IgM) showed a good correlation with HLA-A9 alloantigen detected by conventional typing alloantisera (r = 1.0). Family studies also showed that MA-9 determinant segregated with HLA-A9. MA-10 antibody (IgM) reacted with all HLA-A10 positive lymphocyte donors and cross-reacted with two thirds of HLA-AW33 positive donors. Ml-1 antibody (IgG2a) reacted with all the panel cells tested and immunoprecipitated a molecule of 43,000 daltons from Nonidet P-40 lysates of 3H-glucosamine-labelled cells. The results showed that MA-9 and MA-10 antibodies can be used as routine tissue typing reagents.

Monoclonal antibodies in urology

The recent development of hybridoma technology has made it possible to obtain large quantities of antibody against a single determinant (monoclonal antibodies). This review describes the history of hybridoma technology and the method of producing monoclonal antibodies. It examines the role of such antibodies in diagnosis, tissue typing, histochemistry, developmental biology and study and treatment of diseases, including cancer, emphasizing the work being done on urological diseases.

HLA-B27 haplotypes in family studies of ankylosing spondylitis

Although HLA-B27 carries a high relative risk for development of ankylosing spondylitis (AS), most B27 positive individuals do not have spondylitis. One interpretation of this observation is that there may be 2 types of B27, 1 which carries the risk factor and 1 which does not. If this were the case, then with the help of markers closely linked to HLA-B, it might be possible to detect differences between the B27 haplotypes in AS patients and those in healthy probands. We studied 197 members of 18 families with known AS and 110 members of 19 families in which HLA-B27 was present without any known inflammatory spinal disease. HLA antigens A, B, and C and alleles of complement components C2, C4, and Factor B and glyoxalase-1 were determined in all cases. Detailed haplotypes were assigned and their associations with development of the disease were examined. We were unable to identify any distinct HLA-B27 haplotype associated with AS; 2 common haplotypes and several miscellaneous ones were found in both groups. Thinking that the development of AS might be influenced by the other, non-B27 haplotype, we analyzed this and found that there was no detectable influence. The data do not contradict the notion that B27 in whites is a single entity and is itself the susceptibility factor predisposing to the development of ankylosing spondylitis.

Description of a mouse monoclonal anti-HLA-B27 antibody HLA-ABC-m3

The production and characterization of a new anti-HLA-B27 monoclonal antibody HLA-ABC-m3 is described. This cytotoxic IgG2a antibody binds protein A and is able to precipitate cell surface molecules of 43,000 and 12,000 daltons corresponding to the HLA heavy chain and beta 2-microglobulin. Population testing revealed that the HLA-ABC-m3 antibody reacted with the peripheral blood lymphocytes of 47/47 individuals conventionally typed as HLA-B27+ and with 5/105 HLA-B27- individuals. These five extra reactions were with individuals expressing the cross-reactive HLA-B7 alloantigen, although the affinity of the monoclonal antibody for B27 heterozygous individuals (approx 10(9) M-1) was tenfold greater than with B7 individuals (approx 10(8) M-1). In addition, HLA-ABC-m3 reactivity segregated with HLA-B27 in two families. This monoclonal antibody should be of value in the investigation of the role of HLA-B27 in disease.

Quantitative and qualitative differences in the distribution of HLA class I antigenic determinants in the human thymic compartments

The topographical distribution of HLA class I antigens has been investigated by the immunoperoxidase technique on normal frozen thymic tissue sections with a panel of mono- and polymorphic monoclonal anti-HLA antibodies. HLA class I framework determinants detected by the monoclonal antibody W6/32.HL were present on 80-90% of cortical thymocytes, as well as on all cortical epithelial and medullary cells. However the staining intensity of cortical thymocytes with this reagent was about threefold weaker than that of the medullary thymocytes. Labelling patterns of selected monoclonal antibodies against matching HLA-A/B allospecificities revealed striking variations in the quantitative expression of certain HLA-A vs. HLA-B locus alloantigenic determinants on cortical thymocytes compared to a consistent staining on almost all medullary cells.

The definition of an MB related specificity by a monoclonal antibody

A number of monoclonal antibodies have been described that react with monomorphic and polymorphic Ia-like specificities on human B cells, but it is not clear whether these react with HLA-DR encoded molecules or with the products of other closely linked genes within the MHC, such as MB, MT, or DC 1 antigens. A monoclonal antibody is described herein (MC-26.1) which detects a new Ia-like specificity as shown by B-cell reactivity, chemistry, family studies, including recombinant family and coprecipitation studies. The latter studies showed that specificity detected by the MC-26.1 antibody coprecipitated with determinants detected by conventional anti-MB3 and MT3, but not with HLA-DR4 antisera. The determinant was polymorphic but not related to any of the known MB or MT specificities. However, cross-reactions were demonstrated by the variability of reaction on different individuals. Coprecipitation studies indicate that the antigen defined by MC-26.1 coprecipitates with MB and MT specificities suggesting that the antibody defines a new specificity on the MB3 and MT3 molecules.

Monoclonal antibody against HLA-Aw32 + A25. Is HLA-Aw32 an allele with no unique antigenic determinant?

In the present paper we describe the production and characterization of a monoclonal antibody (Mab) recognizing HLA-Aw32 + A25 antigens. NS1 murine myeloma cells were fused with splenocytes from a BALB/c mouse immunized with normal human peripheral blood (PB) lymphocytes of phenotype A1, Aw32; B7,B37,Cw-,Cw-;DR2,DRw10. Supernatants were first screened against Cr51-labeled immunizing cells by complement dependent cytotoxicity 51Cr-CDC). Cultures identified as producing cytotoxic antibodies were subcultured and the supernatants tested against a selected panel of HLA typed cells by the NIH microcytotoxicity method. One culture producing antibody reacting with an HLA polymorphism was detected. This hybrid, designated CATA 1, was cloned twice by limiting dilution and obtained in ascitic form. Specificity of CATA 1 Mab was evaluated against a panel of 120 PB T cells from normal donors. CATA 1 reacted with cells bearing HLA-A25 or HLA-Aw32 antigens. In addition, a reaction was observed with a cell of phenotype A2,Aw31; B17,Bw49. Isoelectric focusing revealed the monoclonal nature of CATA 1, with immunofixation identifying it as an IgG molecule. Absorption studies have demonstrated that CATA 1 recognizes a common determinant on HLA-A25 and HLA-Aw32. The finding that this Mab recognizes the same CREG as alloantisera against HLA-Aw32 suggests that this antigen has no unique epitopes.