Increased HLA-B heterozygosity with age

Immunogenetics of longevity. Is major histocompatibility complex polymorphism relevant to the control of human longevity? A review of literature data

Literature data suggest that human longevity may be directly correlated with optimal functioning of the immune system. Therefore, it is likely that one of the genetic determinants of longevity resides in those polymorphisms for the immune system genes that regulate immune responses. Accordingly, studies performed on mice have suggested that the Major Histocompatibility Complex (MHC), known to control a variety of immune functions, is associated with the life span of the strains. In the last 25 years, a fair number of cross-sectional studies that searched for the role of HLA (the human MHC) genes on human longevity by comparing HLA antigen frequencies between groups of young and elderly persons have been published, but conflicting findings have been obtained. In fact, the same HLA antigens are increased in some studies, decreased in others and unchanged in others. On the whole, that could lead us to hypothesize that the observed age-related differences in the frequency of HLA antigens are due to bias. In our opinion, this hypothesis is real for most studies owing to major methodological problems. However, some studies that do not meet these biases have shown an association between longevity and some HLA-DR alleles or HLA-B8,DR3 haplotype, known to be involved in the antigen non-specific control of immune response. Thus, HLA studies in man may be interpreted to support suggestions derived from the studies on congenic mice on MHC effects on longevity. However, in mice the association may be by way of susceptibility to lymphomas whereas, in human beings, the effect on longevity is likely, via infectious disease susceptibility. Longevity is associated with positive or negative selection of alleles (or haplotypes) that respectively confer resistance or susceptibility to disease(s), via peptide presentation or via antigen non-specific control of the immune response.

HLA, aging, and longevity: a critical reappraisal

Despite a large number of studies, available data do not allow at present to reach definitive and clear conclusions on role of HLA on longevity, owing to major methodological problems, such as serological and molecular typing of different loci, insufficient sample sizes, different inclusion criteria and age cut-off, inappropriate mixing of data referred to people from 58 to over 100 years of age, inappropriate control matching, and neglected consideration of sex-related effects and the different genetic make-up of studied populations. However, within this confused scenario, some data emerge. First, two studies that do not fit the biases above discussed show that some HLA alleles are associated with longevity. However, some of these alleles may confer an increased risk to undergo a variety of diseases. Second, longevity may be associated with an increased homozygosity at HLA loci. Third, an intriguing association between longevity and the 8.1 ancestral haplotype (AH), which has been proven to be associated with a variety of immune dysfunctions and autoimmune diseases, apparently emerges. This association appears to be a sex-specific (males) longevity contributor, and it is particularly interesting, taking into account that a type 2 (early infancy) --> type 1 (adulthood) --> type 2 (aging) shift of cytokine profile occurs lifelong, and that individuals bearing this haplotype show a type 2 immune responsiveness (note that type 1 cytokines mainly enhance cellular responses, whereas type 2 cytokines predominantly enhance humoral responses). On the whole, the (sex specific) association of longevity with alleles or haplotypes of several genes related to risk factors for a variety of diseases (cardiovascular diseases, cancer), including HLA alleles and haplotypes, is not unexpected on the basis of previous studies on the genetics of longevity in centenarians. This association can be interpreted under the perspective of a well known evolutionary theory of aging (antagonistic pleiotropy). This theory predicts that the same gene (or allele or haplotype) can have different roles (positive or negative) in different periods of the life span. Thus, the 8.1 AH should exert a positive effect during the infancy and aging but not in adulthood, when, indeed it is associated to susceptibility to a variety of diseases.

HLA and longevity or aging among Shanghai Chinese

Twenty-two centenarians and one hundred and seventy-nine nonagenarians (mean age 93 +/- 1.04 years) in the Shanghai Region of China were phenotyped for alleles of A (13 types), B (21 types) and C (6 types) loci of the human leukocyte antigen (HLA). The frequencies of HLA antigens were compared with 211 healthy adults whose ages ranged from 20 to 50 years. It was observed that A9 was highly associated with longevity (frequency in the longevity group is 38%, the control group 24%, P = 0.002). A30 showed marked inverse correlation (frequency in the longevity group is 8%, the control group 17%, P = 0.008). Cw3, Cw6 and Cw7 were also inversely correlated (P = 0.02, 0.04 and 0.02, respectively). Thus, it is likely that A9 may contribute to longevity while A30, Cw3, Cw6 and Cw7 may be associated with aging. The average superoxide dismutase (SOD) contents of erythrocytes in 48 cases with the HLA-A9 (without A30) antigen in the longevity group and in 13 cases with the HLA-A30 (without A9) antigen in the control group were 555 +/- 96 and 593 +/- 58 micrograms/gHb, respectively (t = 1.375, P > 0.05).

Is the phenotypic combination A1B8Cw7DR3 a marker for male longevity?

OBJECTIVE

To study whether individual Human Leucocyte Antigens (HLA) at the HLA 1 or 11 loci or the phenotypic combination A1B8Cw7DR3 were associated with longevity.

DESIGN

Direct comparison of the > 90-year-old subjects with a control group.

SETTING

Northern Ireland population with little migratory mobility.

SUBJECTS

The > 90-year-old group (79 females, 38 males) was compared with a control group consisting of 150 unrelated blood donors (81 females, 69 males).

MEASUREMENTS

Human Leucocyte Antigen (HLA) Class 1 typing was carried out on 117 nonagenarians (mean age 93.7 years) and 150 younger controls (mean age 33.7 years) using conventional serological methods; HLA DR typing was carried out on 102 of the 117 > 90-year-old subjects, together with the 150 control subjects, and performed using restriction fragment length polymorphisms. The frequency of the phenotypic combination A1B8Cw7DR3 was measured in both groups.

RESULTS

There were no significant differences in the HLA antigen frequencies between the very elderly groups and the younger subjects at the A, B, C, and DR loci. The phenotypic combination A1B8Cw7DR3 was significantly increased (X3) in nonagenarian men compared with young men but not between elderly women and young women. There was a trend for increased representation of this phenotype in elderly men compared with women of the same age.

CONCLUSIONS

The frequency of the supratype A1B8Cw7DR3 was significantly increased in very elderly men but not in elderly women. Since this phenotypic combination has been associated with immune surveillance and/or hyperactivity in Caucasians, there is the suggestion that it could influence longevity through immune mechanisms but that sex differences may exist in its influence and expression.

Longevity and heredity in humans. Association with the human leucocyte antigen phenotype

Several arguments support the idea of a link between longevity and heredity, both in experimental animals and in the human species. In mice, genes in the major histocompatibility complex (MHC) are associated with a significant effect on life span. Results of analogous studies in man are confusing and contradictory. We have therefore investigated the question of an association of the human leucocyte antigen (HLA) and longevity in a large and ethnically homogeneous population. Our study population consisted of all 964 available inhabitants aged 85 years and over in the Dutch community of Leiden (pop. 104,000). Our control group comprised 2444 young inhabitants, aged 20-35 years, with an identical ethnic and demographic background. In addition, control groups of different age-brackets from the same region were used. Two antigens differed in frequency: HLA-B40 was lower and HLA-DR5 was higher in the group of 85 years and over, as compared to the control group, aged 20-35 years. Both differences were more evident in females. No major disease associations with HLA-B40 or HLA-DR5 have been reported. It is unlikely that these results are a chance observation: the overall similarity of the HLA pattern of the old and young age groups is a confirmation of their identical ethnic and demographic background and the changes as observed in the different age-groups were gradual. The biological meaning of these results is still unclear.

HLA and T-lymphocyte function in old age

The role of the major histocompatibility complex in the genetic control of reactivity of peripheral blood mononuclear cells (T lymphocytes) to lectins and allogeneic cells as a function of age was investigated. In randomly selected aged subjects the frequencies of HLA-A, B, and some C locus alleles did not differ significantly from those in the control group. However, some tendencies of haplotype frequency differences between young and aged subjects were found. Significant associations of impaired or preserved T-lymphocyte function could be detected in connection with some HLA-A (A3, A11) antigens only. The tendency of some phenotypic HLA-A and B or C and B antigen associations to be in correlation with impaired or preserved T-lymphocyte reactivity in old age seemed to be independent of their age-related frequency differences. In family studies of a partially inbred Hungarian population, differences were found in the rate of diminution of allogeneic reactivity in groups sharing different HLA haplotypes. Based on statistical analysis of these data, a genetic factor segregating with the MHC and taking part in the regulation of the age-dependent decline of T-lymphocyte reactivity can be postulated.

Lack of association between HLA and age in an aging population

In a sample of 228 Framingham Study participants aged 58 to 86 who were typed for HLA, neither frequencies of individual antigens nor heterozygosity at the A or B loci appeared to be related to age. Previously found associations could be chance occurrences, or HLA-related effects on longevity in the general population might be small. It is also possible that such effects occur at younger ages than those included in our study or that HLA is related to the aging process in a way that is detectable only at very advanced ages.

Autoantibodies and immunoglobulin allotypes in healthy North American Blacks of different age groups

A population of 291 healthy North American Black subjects of different ages was studied for immunoglobulin (Ig) allotypes and the prevalence of autoantibodies, to determine possible associations between Ig allotypes and age, autoantibodies and age, and Ig allotypes and autoantibodies. Indirect immunofluorescence was used to detect anti-gastric parietal cell, anti-smooth muscle, anti-thyroid microsomal, anti-nuclear, and anti-mitochondrial antibodies. The sera were typed for the Ig allotypes Gm(1, 2, 3, 5, 6, 13, 14, 17, and 21) and Km(1) with a hemagglutination-inhibition assay. A significant association between advanced age and an increased prevalence of anti-nuclear antibodies was observed in females. There was no significant association between Ig allotypes and the autoantibodies tested. The results suggest that Ig allotypes are not involved in the development of autoantibodies in healthy Blacks.

HLA and longevity

One hundred fifty-five healthy nonagenarians, 45 men and 100 women, all French Caucasians, were phenotyped for alleles of the A, B, C, DR loci of the HLA complex. The observed HLA antigen frequencies were compared to those of a control series of 133 males and 179 females whose ages ranged from 10 to 50 years. When comparing the total young and elderly series, no significant differences were observed with respect to HLA antigen distribution or heterozygosity at any of the loci. When taking sex difference into account, however, an excess of the Cw1 antigen was found in the group of elderly females (p less than 0.001) and an excess of the Cw7 antigen in the group of elderly males (p less than 0.001). Of particular significance was the fact that Cw7 belonged in this instance to a phenotypic combination (and most probably to the corresponding haplotype) A1/Cw7/B8/DR3 which was found significantly increased in male nonagenarians (p less than 0.001). These results support the hypothesis that certain HLA haplotypes are associated with survival advantage.