Advantages of cryopreserved lymphocytes for sequential evaluation of human immune competence. I. Mitogen stimulation

Human lymphocytes were harvested from normal volunteer donors and cryopreserved. Various concentrations of dimethyl sulfoxide and human serum in the cryoprotective media were evaluated to optimize the recovery and function of viable cells. Multiple samples were then drawn from volunteers over a number of days, processed individually, and used in mitogen stimulation assays. These cells were also cryopreserved, immediately thawed, and cultured simultaneously with the fresh cells. In all instances fresh and cryopreserved lymphocytes exhibited similar levels of stimulation by mitogens. Cryopreserved cells from these sequential bleedings were then recovered and cultured simultaneously in mitogen stimulation assays. The results obtained in these assays with cryopreserved cells had less day to day variation than those with cells cultured individually. Coefficients of variance of individual cultures of mitogen stimulation assays were reduced from 26-59% to 5-17% by use of cryopreserved cells. The findings suggested that use of cryopreservation techniques decreases the variability of cellular immune assays and thus allows more accurate longitudinal study of the immune competence of patients.