Immunological status of aged subjects with reference to serological evidence of autoimmunity.

When a group of 104 aged subjects was screened for autoimmune reactions, positive reactions for the rheumatoid factor and/or autoantibodies (ANA, anti-thyroid, PCA, anti-smooth muscle, anti-mitochondria) were recorded in 40.4%. Immunological functions were studied in 32 positive aged subjects, 32 age- and sex-matched negative controls, and 32 young subjects. Some differences attributable to the process of aging were quite evident, such as a depression in the percentage of E rosette forming peripheral lymphocytes and in their response to PHA, and an increase in the percentage of IgG-bearing peripheral lymphocytes and in the serum levels of IgA and three complement fractions (C'3, C'4, and C'3-PA). No clear-cut picture was noted when autoimmunity-positive and -negative, aged subjects were compared. However, some differences between sexes suggest that autoimmune reactions are linked to a depressed T cell function mainly in males, whereas the reverse is true for females.