[Comparison of 2 techniques for measuring lymphocyte proliferation: tritiated methyl-thymidine incorporation and...

In vitro lymphocyte mitogenic stimulation by phytohemagglutinin A was determined in 20 subjects, comparing tritiated thymidine incorporation and nuclear propidium iodide fluorescence. Unexpectedly, no correlation could be found between the two measures. The pitfalls of both methods are reviewed and discussed. The inability to validate one test by the other restricts the interpretation of the results obtained with one method and prevents their generalization. Without another gold-standard at the present time, specific and limited method-dependent norms should be defined.