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

Autoimmunity and geriatrics: clinical significance of autoimmune manifestations in the elderly

The immune system undergoes continuous morphologic and functional changes throughout the years, and it is now believed that the immune response has its peak function in puberty and gradually decreases with age (immunosenescence). Recent studies in healthy octogenarian patients suggest that the immune system, instead of suffering a generalized deterioration, undergoes a remodelling/readjustment of its major functions. Increase in two contrasting phenomena coexist in immunosenescence: on the one hand, a decrease in the capacity of the immune response and, on the other hand autoantibody production. The possible consequences of this progressive 'ageing' of the immune system are the increase in autoimmune phenomena, incidence of neoplasia and predisposition to infections. The study of autoimmune manifestations in elderly populations should be considered a priority for future medical research because of increasing life expectancy, especially in developed countries. This review analyses the main immune disorders associated with immunosenescence, the prevalence and clinical significance of autoantibodies in the elderly and the clinical expression of the main autoimmune diseases in older patients.

The prevalence of autoantibodies in an elderly sub-Saharan African population

In the present prospective, census-based study we have investigated the prevalence of organ-specific and non-organ-specific autoantibodies (AAb) in 152 unselected Cameroonians aged 60 years and older living in the community. AAb were detected in 49% of the participants. Non-organ-specific AAb (47%) predominated over organ-specific AAb (7%). Anti-TPO, anti-Tm, anti-Tg and anti-PC AAb were completely absent. RF was the most frequent AAb, being found in 57 (38%) cases. The prevalences of anti-SMA and RF were significantly higher in women than in men (respectively, P=0.023 and P=0.016). Higher serum concentrations of gammaglobulins were accompanied by a higher prevalence of RF (P < 0.0001) and a lower prevalence of ANA (P=0.036). The overall prevalence of AAb was higher in the filaria-infected (60%) compared to the non-infected (42%) participants (P=0.046). There was no significant influence of the vitamin D status, number of pregnancies, physical activity or medication use on the prevalence of AAb. In this study a heterogeneous pattern for the presence of the various AAb was found. Some AAb, which are commonly encountered in other studies on elderly subjects, were completely absent in this population. This diversified pattern of AAb prevalence therefore argues in favour of exogenous influences in the occurrence of AAb in elderly populations.

Repertoires of natural autoantibodies against muscle tissue are independent of age or gender in normal human adults. A western blot study

Sera from 69 healthy blood donors were screened for autoantibodies using Western blots of human muscle fractions to assess whether prevalence and repertoires of autoantibodies against muscle tissue would change with age. Each serum contained immunoglobulins binding to a broad spectrum of antigens. Their molecular masses ranged from 20 to more than 200 kDa. Although each staining pattern appeared to be a singular combination of detected bands and staining intensities, the patterns were not different in men and women. When sera were grouped according to age (decades between 10 and over 70 years) age-dependent changes were not found. Individual repertoires of natural autoantibodies against muscle tissue are complex when examined by Western blotting. Mature normal repertoires of low-affinity autoantibodies are found at the age of 10 years which is the lower cut-off in this study. The repertoires remain stable throughout a normal lifespan.

Refractory esophageal candidiasis associated with a low molecular weight plasma inhibitor of T-lymphocyte function

In a patient with chronic esophageal candidiasis due to C. tropicalis that was refractory to mycostatin and ketoconazole, a generalized cell-mediated immunodeficiency state was detected. Samples of plasma from this patient inhibited T-lymphocyte function, suppressing both rosette formation and mitogen responsiveness of T-cells derived from the patient and from normal individuals. Following plasma exchange, the patient's immune defect resolved and her candida infection disappeared. On further analysis, the plasma inhibitory factor was found to be of low molecular weight (less than 10,000) and heat labile. Preliminary studies suggested that this inhibitor was candida-derived, since it was removed from plasma by anti-candida antibodies in solid phase. Immunodeficiency in chronic candidiasis may be improved by removal of circulating inhibitory factors through plasma exchange.

Age-related changes in lymphocyte subset proportions, surface differentiation antigen density and plasma membrane fluidity: application of the eurage senieur protocol admission criteria

Peripheral blood lymphocytes from 260 "apparently healthy" males and females, aged 20-97, have been investigated for age-related changes in a number of immunological parameters (percent and number of lymphocytes, OKT 4+ and OKT 8+ cells; OKT 4/8 ratio; intensity of fluorescence of OKT 4 and OKT 8 stained cells; membrane fluidity). Data were then reassessed after exclusion of people who did not conform to the SENIEUR PROTOCOL admission criteria of EURAGE (European Economic Community's Concerted Action Program on Aging) in order to investigate whether the differences observed were attributable to underlying disease. A slight decrease in the number and percentage of lymphocytes, OKT 4+ and especially OKT 8+ cells was found. Intensity of fluorescence of OKT 4 and OKT 8 stained cells from the elderly was reduced and may explain the lower percentages. Membrane fluidity was decreased in old persons (over the age of 75); the free cholesterol/phospholipid molar ratio in the serum increased up to the age of 75 and then declined, and it did not correlate with decreased membrane fluidity. Exclusion of the 20-60% of the study groups who were not eligible for admission according to the SENIEUR PROTOCOL criteria did not affect these results. The feasability and applicability of the PROTOCOL is discussed.

Occurrence of anti-low density lipoprotein antibodies and circulating immune complexes in aged subjects

The incidence of circulating immune complexes, anti-low density lipoprotein (LDL) autoantibodies and the anti-LDL activity of immune complexes was studied in healthy young and aged controls and in patients with vascular diseases. Circulating immune complexes (CIC) frequently occurred both in the young or old patient groups and in the aged healthy control groups, whereas they could not be found in the young controls. Marked differences were found in the incidence of anti-LDL antibodies between the groups tested. In both young and aged control groups such antibodies were very rarely observed (4-5%). In contrast anti-LDL antibodies were present in 35-45% in the aged, or young patients. Similarly, no anti-LDL activity was found in CIC of the controls, whereas in the patients with vascular diseases a significant CIC-associated anti-LDL activity was detected. These results suggest that the presence of anti-LDL antibodies are associated with the arteriosclerotic manifestations, while that of circulating immune complexes is connected by the ageing process itself.

HLA, immunoglobulin allotypes and cell-mediated immunity in retinitis pigmentosa: a family study

Investigation of an informative family including two probands with male multiplex retinitis pigmentosa revealed that the putative disease susceptibility loci were not linked to those of HLA. In addition, analysis of immunological data obtained yielded evidence suggestive of X-linked inheritance of susceptibility to cell-mediated immune aberration in this family.

Immunological profiles in alopecia areata

Cell-mediated immunity and auto-immune phenomena were investigated in sixty patients with active alopecia areata of various degrees of severity. Serum auto-antibodies to thyroid antigens were detected in twenty-three patients. Examination of T-lymphocyte populations, lymphocyte DNA synthesis, and lymphokine production in response to mitogen stimulation revealed no differences between the sixty patients and matched healthy control subjects. However, patients with thyroid auto-immunity and/or the presence of alopecia totalis or universalis showed significant reductions in interactive T lymphocytes (recognized by rosette formation with human B lymphoblastoid cells) and diminished production of leukocyte migration inhibition factor in response to stimulation with phytohaemagglutinin. This suggests that immune mechanisms may be involved in the pathogenesis of alopecia areata which is associated with thyroid auto-immunity or which progresses to total hair loss.