Rapid lymphocyte immunoreactivity test utilizing [3H]uridine in vitro.

A microculture assay utilizing [3H]uridine incorporation was developed to test murine spleen lymphocyte immunoreactivity in vitro. Parameters of the culture technique which included cell density, doses of LPS, Con A, PHA, [3H]uridine levels, and length of culture time were investigated. Responses were detectable at 4 h for all 3 mitogens, with labeling ranging up to 180% of the control value. By 8 h there was a 200--350% increase in mitogen-induced incorporation of radioactivity. Similar increases were observed in a serum-free system. The responses were the result of increased incorporation of label by stimulated cultures rather than decreased labeling of non-mitogen treated cultures over time. The [3H]uridine incorporation was demonstrated to be the selective response of T or B cell populations when stimulated with appropriate lectins. This assay detects early RNA synthesis, as supported by experimental observations in which accumulation of radioactivity in stimulated lymphocytes was TCA precipitable, resistant to SDS treatment, and inhibited by actinomycin D.