Immunological competence is known to vary with age, and such age-related variations are often parabolic in nature . For example, both the level and avidity of the antibody response increase during postnatal development, reach a maximum in adulthood, and then decline during senescence (1). Cellular changes in the T lymphocyte compartment (both helper and suppressor T cell levels) appear to account for most variations in immunological competence (1, 2). Relatively few studies have attempted to correlate these functional changes with variations in the levels and nature of molecules expressed by immunocompetent lymphocytes. A study has therefore been undertaken to evaluate the glycosylation status of IgG during the natural history of human life .Human serum IgG has been reported to carry at least 30 different N-linked oligosaccharides, all of which are of the biantennary complex type, and most of which (>95%) carry N-acetylglucosamine in both outer arms (3, 4). Structural differences between these arise primarily from core-substitutions (i .e., fucose and the`bisecting' G1cNAc), outer-arm galactosylation, and sialylation (Fig. 1 a). We have previously reported that the percentage incidence of agalactosyl structures on the serum IgG of a group of patients with active rheumatoid arthritis (mean age 62 yr) was -51%, placing this group well above the average for a group of normal individuals (3, 5) .We now report that the galactosylation of IgG N-linked oligosaccharide changes as a parabolic function of age. This seemingly parallels changes in immunological competence and draws attention to the need to monitor agedependent variations in the expression of oligosaccharides in addition to those related to differences in cell type (6). Volume 167 May 1988 1731-1736 Materials and Methods Brief Definitive ReportSerum was obtained from 151 individuals of both sexes and varying in age from 1-70 yr . None of the individuals >15 yr old were known to have any pathological abnormalities, nor to have had any history of autoimmune disease, although some of the older individuals may have had subclinical levels of age-related diseases (such as osteoarthritis), but none has as yet presented with major symptoms. All children under the age of 15 yr who were studied were undergoing ear, nose, and throat surgery, hernia repairs, or treat-R. B. Parekh, R. A. Dwek, and T. W. Rademacher are members of the Oxford Glycobiology Unit, which is supported by the Monsanto Co .

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To investigate potential mechanisms controlling protein glycosylation we have studied the interrelationship between lymphocytic galactosyltransferase (GTase) activity and serum agalactosylated immunoglobulin G levels (G(0)) in healthy individuals and patients with rheumatoid arthritis and non-autoimmune arthritis. In RA there was reduced GTase activity and increased G(0). A positive linear correlation between B and T cell GTase was found in all individuals. The relationship between GTase and G(0) was found to be positive and linear in the control population and negative and linear in the RA population. Sulphasalazine therapy maintained normal levels of GTase and caused a reduction in G(0) in the RA population. IgG anti-GTase antibodies (abs) were significantly increased in the RA population, whereas IgM anti-GTase abs were significantly decreased in both the RA and the non-autoimmune arthritis groups. These data describe a defect in RA lymphocytic