p53 protein detected by two different antibodies: relationship to proliferation and prognosis in acute lymphoblastic...

The expression of p53 protein was examined in a series of 69 children with acute lymphoblastic leukemia with two different monoclonal antibodies (Mab 1801 and 240). p53 expression was detected with at least one antibody in 49 cases (71%), whereas only 19 cases (27%) were positive with both antibodies. Variability in the immunostaining could be observed depending on the antibody used. Mab 240 gave the highest rate of positive staining (58%), followed by 1801 with 39%. Positive staining with 1801 was significantly associated with decreased proliferation of tumor cells as measured by Ki-67 labelling, indicating that possibly the wild-type p53 protein is preferably stained with this antibody. However, neither of the two antibodies has prognostic value or is correlated with histopathological parameters.