Mixed lymphocyte reactions evaluated by means of bromodeoxyuridine incorporation.

The mixed lymphocyte reactions are usually performed by the uptake of 3H thymidine (3H TdR) in the study of histocompatibility for allogeneic bone marrow transplantation. Bromodeoxyuridine (BrdUrd), an analogue of thymidine, can be used as an alternative marker of proliferation. In this study we compared the evaluation of the proliferative activity of alloreactive lymphocytes in MLR by 3H TdR and BrdUrd incorporation in flow cytometry. The results show that BrdUrd is able to recognize proliferative activity at least 24-48 hours before 3H TdR, and allows discrimination of proliferation of a few cells despite its proximity to the autologous controls. However, the large quantity of cells needed for every combination is presently a disadvantage of the method.