Enhancement of E rosette formation by incubation of lymphocytes in cerebrospinal fluid dilutions.

Lymphocytes from normal donors were incubated for 4 h at 37 degrees C in dilutions of normal cerebrospinal fluid (CSF) in Hank's balanced salt solution (HBSS), before being tested for "active" and "total" sheep erythrocyte rosette-forming cells (E-RFC). Incubation in CSF dilutions caused an increase in the percentage of both "active" and "total" E-RFC compared to incubation in HBSS. Incubation in HBSS caused a decrease in "total" but not in "active" E-RFC percentages. CSF thus effects an increase in the ability to form E-RFC under suboptimal conditions. No mitogenic effect of CSF was observed in lymphocyte culture experiments.