Optimizing whole blood lymphocyte proliferation in the rat

Use of whole blood for lymphocyte proliferation experiments have advantages over the usual isolated lymphocyte procedure. We have systematically optimized methodology for whole blood lymphocyte proliferation in male Sprague-Dawley rats. Both phytohemagglutinin (PHA) and concanavalin A (ConA) stimulate lymphocyte blastogenesis in whole blood. The response of rat lymphocytes to ConA at supra-optimum conditions doubled that of PHA in contrast to what is observed in human lymphocytes. Proliferation rates relate non-linearly to concentrations of both mitogens with profiles showing lag, log and decline phases with increasing concentrations. The effect of incubation period followed a similar pattern with an optimum growth rate at 72 h. Whole blood from adrenalectomized rats gave higher proliferation rates than blood from intact normal rats. Advantages of the technique include: use of as little as 8 μl of blood for each determination; rats need not be killed; the technique is less cumbersome, less time consuming, and cheaper to carry out than the traditional isolated lymphocyte method.