Evaluation of canine lymphocyte proliferation: comparison of three different colorimetric methods with the H-3-thymidine incorporation assay

To evaluate canine lymphocyte stimulation the radioactive thymidine incorpo ration assay is still the method of choice. In order to find a suitable non -radioactive alternative to the standard H-3- thymidine incorporation assay , proliferation of canine peripheral blood lymphocytes (PBL) was measured w ith three different colorimetric assays, using the two tetrazolium salts MT T and XTT and 5-bromo-deoxyuridine (BrdU). Isolated canine PBL were stimula ted with two different mitogens, Concanavalin A (Con A) and Phytohemaggluti nin (PHA), using different culture conditions. Applying statistical analysi s we found that BrdU and MTT showed a high correlation to the H-3-thymidine incorporation assay, although the BrdU assay proved to be more sensitive t han the MTT assay. No significant correlation between the XTT assay and the radioactive method was demonstrated, Consequently, the BrdU assay is the m ost suitable alternative to the radioactive method. (C) 1999 Elsevier Scien ce B.V. All rights reserved.