Variables in the quantitation of the mixed leucocyte response by tritiated thymidine uptake.

We have used H-thymidine uptake to quantitate the mixed leucocyte response. The technique of H-thymidine labelling is an important variable in the total mixed leucocyte culture technique. The effect of variations in the specific activity of H-thymidine used, the amount of radioactivity added per culture and the time of exposure to H-thymidine was studied using a micro-MLC method. Optimum quantitative and qualitative discrimination was obtained by the addition of high specific activity thymidine for an exposure period of 18–24 hr.