Serum lymphocytotoxins and lymphocyte responses to mitogens of Down syndrome person.

Lymphocyte responses to phytohemagglutinin P (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) and incidence of serum lymphocytotoxins in 20 Down syndrome persons were investigated. There was no change in lymphocyte blastogenesis to mitogens in younger Down syndrome individuals (less than 30 years of age) as compared to control persons. The lymphocytes of Down syndrome subjects over 30 years of age showed significantly decreased responses to PHA, Con A, and PWM. Results suggest that with increasing age, Down syndrome persons seem to have an impairment in lymphocyte function. Serum lymphocytotoxins that were not related to age occurred in 4 of the Down syndrome subjects (20 percent). There was no correlation between the presence of lymphocytotoxins and lymphocyte blastogenesis in these subjects.