Genetic mapping of Ir locus in man: linkage to second locus of HL-A

Advances in asthma and allergic disease genetics: Is bigger always better?

This review focuses on genome-wide association studies (GWASs) of asthma and allergic diseases published between January 1, 2018, and June 30, 2019. During this time period, there were 38 GWASs reported in 19 articles, including the largest performed to date for many of these conditions. Overall, we learned that childhood-onset asthma is associated with the most independent loci compared with other defined groups of asthma and allergic disease cases; adult-onset asthma and moderate-to-severe asthma are associated with fewer genes, which are largely a subset of those associated with childhood-onset asthma. There is significant genetic overlap between asthma and allergic diseases, particularly with respect to childhood-onset asthma, which involves genes that reflect the importance of barrier function biology, and to HLA region genes, which are the most frequently associated genes overall in both groups of diseases. Although the largest GWASs in African American and Latino/Hispanic populations were reported during this period, they are still significantly underpowered compared with studies reported in populations of European ancestry, highlighting the need for larger studies, particularly in patients with childhood-onset asthma and allergic diseases, in these important populations that carry the greatest burden of disease.

[Uveitis-associated HLA class 1 histocompatibility antigens]

AIM

to evaluate the diagnostic and prognostic significance of HLA class 1 histocompatibility antigens in the development of anterior uveitis.

MATERIAL AND METHODS

A total of 137 patients with anterior uveitis followed up at the Research Institute of Eye Diseases in 2009-2016 were tested for HLA antigens (A and B loci). The average patient's age was 29±12.4 years. All patients underwent a thorough medical interview with clinical and laboratory assessment. In case of suspected association with systemic disease, the patients were referred for consultation at the V.A. Nasonova Research Institute of Rheumatology. HLA typing was performed using a standard microlymphocytotoxicity test with specific anti-HLA sera (production of Gisans CC, Saint Petersburg). Statistical processing was performed with Statistica 6.0 software by applying methods of descriptive and nonparametric statistics (Mann-Whitney test).

RESULTS

The results of HLA class 1 typing indicated a significant positive association between uveitis and the HLA-B27 antigen (p<0.00001). Moreover, there was a trend toward decreased frequencies of В7, B12, and B21 antigens (p=0.1), however, the changes were not statistically significant as compared to the control group. Other HLA class 1 antigens also did not differ significantly in frequency between uveitis patients and the controls.

CONCLUSION

The study has confirmed an association between certain histocompatibility antigens and systemic diseases. However, a statistically reliable relationship has been established only for the HLA-B27 antigen.

The genetics of asthma and allergic disease: a 21st century perspective

Asthma and allergy are common conditions with complex etiologies involving both genetic and environmental contributions. Recent genome-wide association studies (GWAS) and meta-analyses of GWAS have begun to shed light on both common and distinct pathways that contribute to asthma and allergic diseases. Associations with variation in genes encoding the epithelial cell-derived cytokines, interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), and the IL1RL1 gene encoding the IL-33 receptor, ST2, highlight the central roles for innate immune response pathways that promote the activation and differentiation of T-helper 2 cells in the pathogenesis of both asthma and allergic diseases. In contrast, variation at the 17q21 asthma locus, encoding the ORMDL3 and GSDML genes, is specifically associated with risk for childhood onset asthma. These and other genetic findings are providing a list of well-validated asthma and allergy susceptibility genes that are expanding our understanding of the common and unique biological pathways that are dysregulated in these related conditions. Ongoing studies will continue to broaden our understanding of asthma and allergy and unravel the mechanisms for the development of these complex traits.

Genetic regulation of Dermatophagoides pteronyssinus-specific IgE responsiveness: a genome-wide multipoint linkage analysis in families recruited through 2 asthmatic sibs. Collaborative Study on the Genetics of Asthma (CSGA)

BACKGROUND

Dermatophagoides pteronyssinus (Der p) is one of the most frequently implicated allergens in atopic diseases. Although HLA could play an important role in the development of the IgE response to the Der p allergens, genetic regulation by non-HLA genes influences certain HLA-associated IgE responses to complex allergens.

OBJECTIVE

To clarify genetic control for the expression of Der p-specific IgE responsiveness, we conducted a genome-wide search for genes influencing Der p-specific IgE antibody levels by using 45 Caucasian and 53 African American families ascertained as part of the Collaborative Study on the Genetics of Asthma (CSGA).

METHODS

Specific IgE antibody levels to the Der p crude allergen and to the purified allergens Der p 1 and Der p 2 were measured. Multipoint, nonparametric linkage analysis of 370 polymorphic markers was performed with the GENEHUNTER program.

RESULTS

The best evidence of genes controlling specific IgE response to Der p was obtained in 2 novel regions: chromosomes 2q21-q23 (P = .0033 for Caucasian subjects) and 8p23-p21 (P = .0011 for African American subjects). Three regions previously proposed as candidate regions for atopy, total IgE, or asthma also showed evidence for linkage to Der p-specific IgE responsiveness: 6p21 (P = .0064) and 13q32-q34 (P = 0.0064) in Caucasian subjects and 5q23-q33 (P = 0.0071) in African American subjects.

CONCLUSIONS

No single locus generated overwhelming evidence for linkage in terms of established criteria and guidelines for a genome-wide screening, which supports previous assertions of a heterogeneous etiology for Der p-specific IgE responsiveness. Two novel regions, 2q21-q23 and 8p23-p21, that were identified in this study merit additional study.

Association of pyrazolone drug hypersensitivity with HLA-DQ and DR antigens

BACKGROUND

In sensitive patients pyrazolone drugs can precipitate adverse reactions ranging from urticaria and angioedema to anaphylactic shock, presumably by immunological, IgE-mediated mechanism. However, up to now no genetic factors influencing the development of allergic reaction have been reported in this type of hypersensitivity.

OBJECTIVE

The aim of our study was the investigation whether the susceptibility to development of pyrazolone drugs hypersensitivity (PDH) reactions was associated with HLA class II antigens.

METHODS

To test this hypothesis we studied the distribution of HLA-DR and DQ antigens in 26 pyrazolone sensitive patients and control groups including unselected general population and clearly defined atopic and non-atopic groups.

RESULTS

Significantly higher frequencies of DQ 7 and DR11 antigens were found in PDH group as compared with control unselected population (RR= 16.48, P < 0.0001; P(cor)< 0.002 and RR = 4.57, P = 0.0002; Pcor = 0.003 for DQ and DR antigen respectively). Similarly, statistically significant increased frequencies of DQ 7 and DR11 in patients with PDH were observed compared with atopic control group (RR= 18.43, P < 0.0001; Pcor <0.002 and RR= 6.33, P= 0.0007; Pcor =0.01, for DQ and DR antigen respectively). However, in comparison to non-atopic control group only the frequency of DQ 7 antigen was significantly increased (RR = 15.42, P = 0.0001; Pcor = 0.0015). DQ 7 antigen was present in 46.1% of PDH patients compared with 4.9%, 4.4% and 5.3% in the general population, atopic and non-atopic groups respectively, suggesting pyrazolone hypersensitivity as a trait positively correlated with this HLA antigen.

CONCLUSION

Our data suggest a genetic predisposition to pyrazolone hypersensitivity reactions, linked to HLA-DQ locus.

Olive pollen allergy: searching for immunodominant T-cell epitopes on the Ole e 1 molecule

BACKGROUND

The amino-acid and nucleotide sequence of Ole e 1 (the major antigen of olive pollen) has been described and the IgE antibody response to this major allergen was associated with DR7/DQ2 antigens. With this previous data we try to define the T-cell epitopes implicated in Ole e 1 reactivity.

OBJECTIVES

To study the recognition of T cells (derived from allergic and non-allergic Ole e 1 patients) to Ole e 1 synthetic peptides in order to define immunodominant T-cell epitopes.

METHODS

We have compared the proliferative response of the peripheral blood mononuclear cells from Ole e 1 sensitized patients vs. non-sensitized controls, induced by 14 Ole e 1 synthetic peptides. Thirty subjects were classified in two groups: group 1 (non-responders against Ole e 1, n=16) and group 2 (Ole e 1 responders, n=14), according to their clinical parameters and the presence or not in their sera of the significant Ole e 1 IgE antibody levels.

RESULTS

Our results shown that it is possible to find T cells reactive to Ole e 1 peptides in patients with and without significant levels of Ole e 1 IgE antibodies. However, the percentage of response was higher in patients with IgE antibodies 71.4% vs 25%), and the recognition profile was different: the control group showed a broad reactivity pattern, in contrast, the response by the 'Ole e 1 responders' group was mainly directed against three peptides of the carboxi-terminal region, peptides 10 (91-102), 12 (109-120) and 13 (119-130), with a response frequency of 35.7, 28.5 and 28.5%, respectively. By direct and inhibition test no antibody response was found against the synthetic peptides.

CONCLUSIONS

Our data suggest that the regions between 91 and 102 and 109-130 aminoacids on the Ole e 1 molecule are immunodominant T-cell epitopes. These epitopes are not recognized by IgE antibodies.

Genetic susceptibility to asthma in a changing environment

There is a major interest in investigating the genetic components of allergy and asthma. Four different areas are involved in the study of complex genetic diseases: family studies, assessment of phenotype, segregation analysis and gene mapping. Initial assessment of phenotype must be practical, reproducible and relatively independent of compounding variables. Phenotypes important in allergy and asthma include atopic parameters such as total serum IgE, bronchial hyper-responsiveness and the presence/ absence of clinical asthma. Numerous family and twin studies have suggested the presence of a heritable component for allergy, bronchial hyper-responsiveness and asthma. The number of genes involved in these complex genetic disorders and their mode of inheritance have not been fully determined. Our group has been involved in a collaborative US-Dutch study in which 92 families with over 500 individuals have been phenotyped and DNA has been obtained for genotyping. Initial results of the classification of family members show that approximately 26% of the offspring of families ascertained through a parent with asthma have an asthmatic phenotype. A large number of these offspring with clinical evidence of asthma do not have a prior physician diagnosis of asthma, suggesting that there is a spectrum which ranges from preclinical to symptomatic asthma. The familial aggregation of asthma and other obstructive airway diseases in these families is consistent with a significant genetic component. Initial linkage studies have been performed on two characteristics of the allergic and asthmatic phenotype. Total serum IgE was analysed because this measure correlates with the clinical expression of allergy, bronchial hyper-responsiveness and asthma. Segregation analysis of total serum IgE provided evidence for a recessive mode of inheritance. Sib pair analyses and maximum likelihood scores suggest that a gene regulating IgE production maps to chromosome 5q. Bronchial hyper-responsiveness and total serum IgE are related to asthma in population-based studies. Sib pair analyses for bronchial responsiveness showed significant linkage to markers on chromosome 5q.

Genetic analysis of atopy in three large kindreds: no evidence of linkage to D11S97

Both genetic and environmental influences have been implicated in the pathogenesis of atopic disease. A recent report suggested that a major gene providing susceptibility to atopy was transmitted in a pattern consistent with autosomal dominant inheritance and evidence was presented that places the disease locus near the D11S97 marker on human chromosome 11q. In this report, we present three large, highly characterized pedigrees in which atopy is transmitted in a pattern consistent with autosomal dominant inheritance. Genotypes at the D11S97 and HLA loci were evaluated using both lod score and sib pair methods of analysis. In these pedigrees, we reject close moderate linkage (up to 10 cM) of atopy with both D11S97 and HLA.

Immediate hypersensitivity to Parthenium hysterophorus. I. Association of HLA antigens and Parthenium rhinitis

Lymphocytes collected from rhinitis subjects with strong positive skin reactions to the pollen allergens of Parthenium hysterophorus (American feverfew) having moderate to high titres of Parthenium-specific serum IgE were analysed for association of HLA-antigens covering 13 specificities of HLA-A, 17 specificities of HLA-B and eight specificities of HLA-DR loci by the NIH two-stage microlymphocytotoxicity assay. Comparison of the phenotypic frequencies of HLA-A and B antigens between Parthenium rhinitis subjects (n = 22) and control subjects (n = 137) did not suggest any significant association when tested for these antigen specificities. A significant correlation in the association of HLA-DR3 antigen with a relative risk of 11.33, however, was observed in Parthenium rhinitis subjects (n = 30) when compared to controls (n = 50).

HLA haplotype segregation in families with allergic asthma

In order to evaluate genetic linkage between Allergic Asthma (AA) and the HLA system, we studied 20 families having AA affected sib pairs and 8 families with Intrinsic Asthma (IA) affected sib pairs. All AA patients had a strong IgE immune response to the mite D. farinae. Serological HLA typing (A, B, C, DR, and DQ antigens) was performed by the standard microcytotoxicity assay. Genetic analysis was made by means of the "Affected sib pairs" method. Out of the 20 affected sib pairs, 14 shared two HLA haplotypes, five shared one HLA haplotype and one was HLA-non-identical. These results differed significantly from the random ratio 1:2:1 for sharing, 2, 1 or 0 haplotypes (p less than 0.0001), and was very close to that expected for a recessive mode of inheritance. In contrast, among the IA sib pairs there was not an important distortion in the pattern of haplotypes segregation. However, a significant association between any of the HLA alleles and the two types of Asthma studied was not found. The results suggest the existence of an HLA-linked recessive gene controlling the IgE immune responsiveness to mite allergens and conferring susceptibility to AA.

Human castor bean allergy and HLA-A, B, C, DR

Our results in 27 castor bean-allergic patients typed for HLA-A, B, C, DR antigens show (although the observed difference did not reach a statistical significance after correction for the number of tested specificities) an increase of A2 cross-reacting group antigens and, on the other hand, of HLA-A29, B39, CW2, B12, DR2, and especially DR5 (48.1% vs. 26.9% - chi 2 = 5.579; uncorrected p: 0.01 less than p less than 0.02), which possibly participate in haplotypic combinations. The facts that the markers of the haplotype segments involved are more frequent in northern European populations (e.g., A3,B7--Scandinavian; A29,B12--English) and that regional haplotypes are decreased (e.g., A11,B35) suggest that the allergics could in some geographical areas be less genetically adapted to their environment. In the same way, the fact that although the global number of assigned HLA antigens was increased, the percentage of only some alleles (among these those belonging to the A2-CREG) was increased suggests not only a recessive model but a diminution of the polymorphism in allergics. This is in agreement with the physiological role of the HLA system, the polymorphism of which, according to the numerous restriction phenomena allowed at the cellular level, represents broad possibilities of adapted immune response in man. In any event, these findings clearly suggest that HLA-DR5 and B39 may be the markers of castor bean allergy in the Mediterranean area, to which are superimposed the HLA alleles linked to the general atopic susceptibility.

Genetic and immunologic basis of atopic responses

We summarize current understanding of the genetics of human diseases and of the major histocompatibility complex related factors regulating immune responsiveness. Special factors are involved in atopic diseases as a result of the intersection between the immune system, the targets in the tracheobronchial tree and the endocrine, neurologic and genetic mechanisms affecting both the effectors and the targets. The evidence from investigations of human subjects and their families and from laboratory animals for the underlying genetic and immunologic mechanisms of asthma are reviewed. The genetic control of asthma is complex. The evidence suggests a gene or genes associated with and linked to HLA. The disease phenotype may also be regulated by genetically determined levels of IgE and the outcome of the balance between immune response and immunosuppression.

Methacholine inhalation and Gm allotypes in familial asthma

In this paper, we confirmed previous studies where the results showed an incomplete genetic predisposition to allergic asthma. Our results also showed that by using the degree of sensitivity to methacholine and Gm allotypes one can obtain a better characterization than presently available of individual susceptibility to asthma in a familial setting.

HLA-B13 and chronic calcific pancreatitis

In view of a possible role of genetic factors in the etiology of chronic calcific pancreatitis, we undertook a study of the frequency of HLA antigens in this disease. Sixty-four patients with chronic calcific pancreatitis were typed for the HLA-A, -B and -C loci. Fourteen of these 64 patients (21.9%) were found to have antigen B13 compared to 7.5% of 425 controls. These results have a P value of 0.00059 which remains significant (P = 0.020) even when multiplied by the total number of antigens tested. Sex, alcoholism, age at the clinical onset of the disease, presence of pain, and diabetes had no apparent influence on the distribution of HLA alleles. The significant association between chronic calcific pancreatitis and HLA antigen B13 further supports the role of genetic factors in the etiology of the disease.

A study of the inheritance pattern of Romano-Ward syndrome. Prolonged Q-T interval, syncope, and sudden death

Romano-Ward syndrome consists of attacks of syncope, possible sudden death, accompanied by prolonged Q-T interval on ECG. We carried out HLA antigen typing of a family of 16 members having ten cases of Romano-Ward syndrome. All the ten cases had the common HLA haplotype of A9-Bw54, while the six not showing the symptoms did not have A9-Bw54 haplotype. The genes of this syndrome, considered to be inherited through the autosomal dominant patterns, are assumed to have a close linking to the major histocompatibility complex on the short arm of chromosome number 6.

The association of an HLA 'asthma-associated' haplotype and immediate hypersensitivity in familial asthma

Fifty-seven members from ten families in which one parent and at least one child have asthma were studied with dilutional skin tests and RAST to grass pollens after determination of HLA haplotypes. We found no direct evidence for linkage of a hypothetical asthma locus with HLA or for a significant association of asthma with HLA haplotypes. Linkage between the HLA loci and a gene or genes which allow for the expression of clinical asthma could neither be proven nor disproven due to the small sample size. All of the asthmatic children had positive dilutional skin tests and RAST, suggesting that atopic asthma may be genetically controlled by the HLA chromosome (chromosome 6). Nonetheless, determination of the histocompatibility antigens can increase the value of predictive risk analysis for asthma. Such a determination may be important in the early identification of a child born to a family with atopic asthma.

Genetic transmission of serum IgE Levels

Genetic aspects of IgE levels were studied in three large pedigrees, many of whose members had atopic sensitivities to ragweed. Data on 184 persons (80 M, 104 F) were analyzed by the methods of Elston and Stewart after logarithmic transformation and appropriate adjustment for sex and age effects. Several modes of transmission were fitted to the data. The environmental model (of equal transmission frequency for all genotypes) clearly did not fit the data (chi 2 23.03, df 3); this suggested a strong hereditary involvement in IgE distribution. High IgE levels being determined by a dominant allele gave the best fit among the hypotheses examined in pooled data. Under a pure polygenic model, the estimated heritability was 49.5%. Using a mixed model of major gene and polygenic transmission (in an analysis which approximates, but is biased toward inflating the major gene component) polygenic inheritance was found to be 11%, but has no significant improvement over the major gene model. When families are analyzed separately, there was evidence of significant heterogeneity among families. The genetic picture was blurred, with one family favoring recessive inheritance of high IgE levels, one with no clear mode, and the third leaning slightly in favor of dominant inheritance. This suggests that the mechanism is not as simple as was thought and that there may be either two alleles or one gene involved in the determination of IgE levels. The findings are consistent with IgE levels being genetically determined with heritability estimated to be about 50%.

Histocompatibility antigens in asthma: population and family studies

One hundred and twenty-two patients with intrinsic asthma, extrinsic atopic asthma, or asthma with allergic bronchopulmonary aspergillosis were tissue typed for the HLA A, B, and C loci. No associations were found with any of the clinical groups, or with serum total IgE concentrations. Sixty-eight members of 10 families where more than one member was affected by asthma were studied. The segregation of haplotypes in siblings of the propositi who were or were not affected by asthma did not differ from the predicted segregation, and there were no differences when atopy or serum total IgE were considered. No biologically important association between HLA and asthma has been shown.

HLA and sexually transmitted diseases in prostitutes

The HLA profile of 148 unrelated, Chinese prostitutes (56 with repeated gonococcal infection, 31 with syphilis, 31 with gonorrhoea and syphilis, and 30 with no evidence of infection) was compared with that of 238 unrelated, healthy, Chinese control subjects. The joint occurrence of AW19 B17 was observed in 25.8% of prostitutes with double infections compared with 6.7% of control subjects, while that of A11 B15, on the other hand, was associated with a resistance to syphilis and gonorrhoea. The latter profile was observed in 46.7% of prostitutes in business for more than two years who were resistant to disease, in 30% of prostitutes with an overall disease resistance, in 13.4% of control subjects, and in only 3.2% of prostitutes with combined syphilis and gonorrhoea. Because of the statistical uncertainty when multiple variables are being analysed these studies should be repeated in other groups of prostitutes of the same and different ethnic origins.

HLA-antigens and contact hypersensitivity

The HLA-A, -B -C typing of 100 bricklayers was performed. 50 bricklayers had developed contact allergy to chromium while 50 were healthy bricklayers. The distribution of HLA antigens were equal in the 2 groups.

Association between immunoglobulin allotypes and immune responses to Haemophilus influenzae and Meningococcus polysaccharides

Serum samples were collected from 20 healthy White and 33 Black infants before and after immunisation with three doses of diphtheria-pertussis-tetanus vaccine and with one dose of Haemophilus influenzae type b polyribose phosphate vaccine and meningococcal group A and group C polysaccharide vaccines. Antibodies to these immunogens were measured and sera were allotyped for several Gm, A2m, and Km antigens. A highly significant association was found between the Km(1) allotype and the immune responses (difference between post-immunisation and pre-immunisation antibody levels) to H. influenzae and meningococcus C polysaccharides in the White children.

Human immune responses to hapten-conjugated cells. I. Primary and secondary proliferative responses in vitro

An in vitro model was developed to study both primary and secondary proliferative responses of human lymphocytes to hapten-conjugated peripheral blood mononuclear cells. Coculture of human lymphocytes with autologous trinitrophenyl (TNP)-conjugated stimulator cells resulted in primary proliferative responses. Subjects segregated into high and low primary responders with mean stimulation indices of 11 and 2.1, respectively. Restimulation of primed cells from high responder subjects 3 wk after initial sensitization generated secondary proliferative responses. To investigate the antigenic requirements for secondary stimulation, autologous TNP-conjugate primed responders were restimulated with both autologous and allogeneic TNP-conjugated stimulators. In all experiments restimulation with autologous conjugated cells yielded substantially greater proliferative responses than with allogeneic conjugates. Experiments were then performed to ascertain whether HLA determinant homology between primed responder and stimulator cells influenced the level of secondary responsiveness. Homology for HLA-A and B locus serologic determinants was not associated with enhanced responsiveness. In contrast, D region determinant homology, detected by B-cell antigen typing, showed a highly significant positive correlation with the magnitude of secondary responses. The data thus strongly suggest that for secondary proliferative responses to TNP, human T cells recognize hapten in association with HLA-D region determinants.

Detection of acceptor sites on human lymphocytes for antigen-specific T cell factors

Mouse antigen-specific T cell factors are absorbed by human peripheral blood lymphocytes at acceptor sites. The acceptors are products of HLA-linked genes, which may be human immune response genes.

Inherited deficiency of the second component of complement (C2) with membranoproliferative glomerulonephritis

The occurrence of membranoproliferative glomerulonephritis in a 13 year old boy with inherited complete deficiency of the second component of complement (C2) is described here for the first time. Results of the complement studies and the associations of glomerulonephritis with complement deficiencies are discussed.

Inheritance of asthma in families and its linkage to HLA haplotypes

Four families in which asthma occurred in more than three members, and in which there were at least three children, were studied in terms of clinical symptoms, serum IgE levels determined by RIST and RAST, and HLA haplotypes. No association between clinical asthma and serum IgE level was found, but a close association between asthma and a particular HLA haplotype in a family was demonstrated. It was therefore postulated that a disease susceptibility gene closely linked to an HLA gene complex may play a role in the development of asthma.

Strong association between B-lymphocyte group-2 specificity and asthma

30 families in which at least one member has asthma were tested for five new specificities of B lymphocytes as well as for twenty-five HLA antigens. 41 other asthmatic patients were also tested. HLA-B8 was slightly less common than normal in the 71 patients with asthma and there was a trend towards an increased frequency of HLA-A2 in these patients. However, 88% of the 30 asthma patients had B lymphocyte group 2 compared with 24% of the 109 controls. This strong association between asthma and B lymphocyte group 2 was not completely paralleled by linkage with a postulated susceptibility gene of the HLA complex in 9 families whose members were investigated in detail.

The major histocompatibility complex of rhesus monkeys. VI. Serology and genetics of Ia-like antigens

The serology and genetics of11 new cell surface alloantigens of rhesus monkeys are described: They are controlled by the mamor histocompatibility complex but are distinct from the conventional serologically defined (SD) antigens ofRhL-A. The new specifications are termed "Ia-like" because ofserological, immunocytological and other characteristics reminiscent of Ia-antigens of the mouse. Population and family analyses led to the postulation of two segregant series controlling eight of the 11 Ia-like specificities of the monkey. Strong linkage disequilibria with SD2 antigens and genetic mapping on the basis of segregation studies in recombinant offspring in the monkey families, places at least one of the two loci in the vicinity of the SD2 locus of RhL-A, not in the region of the major MLC or LD1 locus. For this and other reasons, the new B-cell alloantigens of rhesus monkeys are not believed to be similar to or associated with the stimulator antigens of LD1. The biological function(s) of the Ia-like antigens of primates are as yet unknown.

Tumor immunology, autoimmunity and aging

Cell-mediated immune function declines with aging, and may be associated with autoimmunity and malignancy. Humoral immune responses also decline with aging. The chief age-related effect on the immune system is a decrease in T-cell function. The "thymus clock" and immunogenesis are discussed in relation to aging. In animals, attempts at immunologic rejuvenation by cellular or hormonal means have not been successful as the results attained by genetic manipulation.

Immunity and survival

Studies in human families and in surviving older persons suggest that the immune system may have an important role in the control of the survival. Immune response (Ir) genes to infectious agents can be detected in human families.

The histocompatibility system and human disease

The histocompatibility system and its associations with human diseases have been described. Although these associations remain unexplained, they represent an important step forward in the search for basic causes and mechanisms of diseases. Further studies may lead to better classifications of diseases and to an increased understanding of basic biologic processes, of etiologies of many important diseases, and of relationships between genetic and environmental susceptibility to disease. However, at the present time histocompatibility studied have little value as diagnostic or prognostic tests in clinical medicine, aside from their obvious usefulness in matching tissue donors to recipients.

Histocompatibility (HLA) antigens and diabetic microangiopathy

To gain further insight into the genetic determinants of diabetic small vessel disease, we studied 22 HLA antigens in 110 juvenile-onset, insulin-dependent diabetics with terminal glomerulosclerosis and retinopathy, who were being prepared for kidney transplant. HLA antigens were comtemporarily determined in non-diabetic kidney transplant recipients and healthy controls. The frequency of antigens A1 and B8 were significantly higher in diabetics than in controls (P less than .02 and .011), but the frequency of BW15 was normal. The data are compatible with the concept that juvenile diabetes with microangiopathy is one of the HLA-B8 associated disorders.

Genetic studies in inbred rats. VI. Linkage relationships of mixed lymphocyte reactivity, serologically defined antigens (Ag-B, Ag-C) and the immune response to poly(Glu52Lys33Tyr15)

The Ag-B allotype, mixed lymphocyte reactivity (MLR) and the immune response to poly(Glu52Lys33Tyr15) were assayed in male rats from the F2 hybrid and two backcross generations of the F344 and DA strains in order to investigate the structure of the rat major histocompatibility complex. No disparity between Ag-B type and mixed lymphocyte reactivity was found in 263 animals. The immune response to poly(Glu52Lys33Tyr15) was closely linked to the Ag-B locus, and both antibody production and the delayed hypersensitivity response were under polygenic control. These results suggest that the genetic loci which determine these responses in the rat are closely linked and that recombinational events between the Ag-B and MLR loci are infrequent.

HLA-B27 and modified bone formation

Of the many associations between histocompatibility antigens and human diseases a prominent one is that between HLA-B27 and inflammatory arthropathies. Hypotheses to explain this association include the B27 gene being linked to a specific immune-response gene required for disease expression and the B27 antigen acting via molecular mimicry with a microorganism or as a microorganism receptor. Alternatively, the HLA-B27 gene might be closely related to a gene which influences bone formation. The finding of a significant association between B27 and Forestier's disease, a disease characterised by abundant new bone formation, supports such a hypothesis.