Abstract
Lymphocyte responsiveness in cells collected from baboons (Papio ursinus orientalis) has consistently been 1/10 of that obtained using human cells. Animals that vigorously rejected organ allografts demonstrated that this lack of responsiveness was not due to genetic identity. This paper defines the kinetics of the baboon mixed lymphocyte response (MLR) and suggests several modifications to improve the sensitivity of the technique. Optimal response was obtained using nylon wool purified T-cell responders, 20% fresh autologous plasma to supplement culture medium, an incubation period of 6 days and exposure to 3H-thymidine (2 Ci/mmol) for 24 h prior to harvesting. These modifications enhanced the MLR response from a stimulation index±standard error of 2·5±0·3 (n=79) to 25·2±5·4 (n=38).