An In Vitro Analogue of Immune Dysfunction with Altered Immunoglobulin Production in the Aged

The consequences of aging of the immune system include impaired T‐lymphocyte responsiveness and aberrant immunoglobulin production. Although T cells from elderly individuals have a well‐described defect in lymphoblastic transformation in response to some polyclonal mitogens, immunoglobulin abnormalities have lacked a clear in vitro model. Peripheral blood mononuclear cells from 13 young and 13 old healthy donors were cultured with phytohemagglutinin (PHA) or pokeweed mitogen (PWM). Old‐donor‐cell phytohemagglutinin (PHA), but not PWM, cultures had significantly lower lymphoblastic transformation compared with young donor cultures. IgG, IgA, and IgM production tended to be lower in old‐versus young‐donor PWM cell cultures. By contrast, despite lower lymphoblastic transformation in old‐donor PHA cell cultures, immunoglobulin production was higher for old‐ versus young‐donor cell cultures. No significant age differences were present in initial lymphocyte counts, percent B cells, T cells or monocytes, or helper /suppressor ratios to explain this enhancement in immunoglobulin production. PHA‐stimulated mononuclear cell cultures in the aged demonstrate not only a defect in proliferation but also increased immunoglobulin production. This in vitro system may be useful to characterize further the pathogenesis of altered immunoglobulin production in the elderly. 1989 The American Geriatrics Society