Abstract
The availability of anti-human dihydrofolate reductase polyclonal antibodies, allowed us to develop an immunohistochemical method improving the tetrazolium salt method for the demonstration of dihydrofolate reductase in samples in peripheral blood and bone marrow. This enzyme, immunohistochemically demonstrated with the alkaline-phosphatase/anti-alkaline-phosphatase (APAAP) method, progressively increased during the normal differentiation of the granulocytopoietic series while it decreased in the erythropoietic series. The lymphocytes showed various positivity patterns which related to their subpopulations. These results were in agreement with previous observations by the tetrazolium salt method. Dihydrofolate reductase may be a useful marker in the study of granulocytic and lymphocytic cell lineages.
