Lymphocyte transformation induced by autologous cells. XI. The effect of age on the autologous mixed lymphocyte reaction.

The autologous mixed lymphocyte reaction (MLR) was lower in newborn infants and healthy subjects over 65 years of age than in adults between the ages of 20 and 32. In contrast, the allogeneic MLR, although impaired in newborn infants, was normal in elderly subjects. The degree of impairment of the autologous MLR in elderly subjects was correlated with the impairment in the response of lymphocytes from elderly subjects to phytohaemagglutinin (PHA) and Staphylococcus aureus proteins A (SPA). The percentage of autorosetting T cells and of T cells with the OKT4 phenotype was increased in elderly subjects. These findings are paradoxical as autoreactive T cells in young adults have been reported to be drawn from these two T-cell subpopulations.