Lack of CD45 antigen on blast cells in childhood acute lymphoblastic leukemia is associated with chromosomal hyperdiploidy and other favorable prognostic features.

The leukocyte common antigen (CD45) was detected on the surface of leukemic cells in 217 (87%) of 249 cases of newly diagnosed childhood acute lymphoblastic leukemia (ALL). All 55 cases of T-lineage ALL, compared with 159 of 191 B-lineage cases, expressed the CD45 antigen (P = .0005). The frequency of CD45 expression did not differ between cases of early pre-B (CD19+, cytoplasmic mu-) and pre-B (CD19+, cytoplasmic mu+) ALL. Cases of ALL lacking CD45 had significantly lower leukocyte counts (P = .002) and serum lactic dehydrogenase (LDH) levels (P = .007) and were more likely to have leukemic cell hyperdiploidy greater than 50 (P less than .0001) or a DNA index greater than 1.15 (P less than .0001), as compared with cases positive for the antigen. Of the 130 patients whose follow-up duration was sufficient for analysis of event-free survival, the 53 with the highest levels of CD45 expression (greater than or equal to 90%) were the most likely to have an adverse event on intensive multiagent chemotherapy. Patients without detectable CD45 had a negligible risk of failure. This study suggests a relationship between the expression of the CD45 antigen on leukemic lymphoblasts and other biologic factors that influence prognosis in ALL.