Lymphocyte response in in vitro cultures to some mitogens, and serum immunoglobulin levels in aged subjects.

Capacity of lympocytes for blastic transformation in in vitro cultures under the influence of PHA and PWM was studied in 40 subjects aged 20--60 years and in 43 aged 60--100 years. In the higher age group, in about 25% of cases, low percentages of blasts in cultures stimulated with PHA and PWM were observed. In 101 subjects aged 65--100 years, the mean level of IgA in serum was significantly higher compared with the 20--40-year age group. In some cases, levels of two or three immunoglobulin classes were raised. The unexplained changes in the reaction of lymphocytes to PHA and PWM and in levels of serum IgG were attributed to the old age of the subjects.