The Factors Affecting the Strength of “One-Way” Stimulation with Irradiated Leukocytes in Mixed Leukocyte Cultures

Abstract

In order to improve the reliability of the technique, we investigated the factors affecting the strength of unidirectional stimulation by irradiated cells in mixed leukocyte cultures. Nonspecific factors included the number of irradiated cells used in the cultures, the dose of x-ray, the time interval between the end of irradiation and preparation of the cultures, and the length of incubation of the cultures. The present results suggest that a satisfactory radiation level for unidirectional quantitation may be 4000 r. The results also indicate that individual-specific factors can affect one-way responses. These factors may be based on histocompatibility differences between the donors of responding and stimulating cells.