CD13 was the commonest cross lineage antigen, expressed in B-ALL (25.6%, n=70/273), followed by CD33 (17.9%, n=49) and combined CD13/CD33 (11.3%, n=31/273) expression.
The aim of our study was to evaluate in a large series of cases of acute lymphoblastic leukemia (ALL) the expression of specific antigens, CD19, CD20, CD22, and CD33, for which MoAbs are available for clinical use.
A 35-year-old man was diagnosed as ALL because of the infiltration of CD10(+)CD19(+)CD33(+)CD34(+) lymphoblasts in the bone marrow and the expression of p190-type BCR/ABL fusion transcript.
We analyzed the expression of the MyAg CD13 and/or CD33 in a cohort of 377 adult patients with de novo ALL enrolled and treated in the GIMEMA ALL 0496 protocol.
Comparison of these and previously published cases demonstrates that the translocation predominately occurs in children and young adults with precursor B-ALL and is typically characterized by low CD10 expression and high CD33 expression.
In whole ALL, CD13/CD33 was associated closely with the presence of stem-cell antigen CD34, and in T-lineage ALL, CD13/CD33 had a significant correlation with additional stem-cell features, such as HLA-DR, multidrug resistance 1 (MDR1) and c-kit gene expression.
As concerns immunophenotypic findings, blast cells from two of three AML patients expressed CD7 and CD34, while those from the T-ALL case displayed CD33 and CD34 along with CD7.
Coexpression of myeloid antigens (CD13 and/or CD33) was observed in six of 16 common ALL patients as well as in the one child with early T-lineage ALL phenotype.
Stimulation of nonleukemic cell population seen in two other cases of cALL was associated with residual erythroid and granulocyte-macrophage colony forming cells after liquid culture as defined in parallel clonogenic assays in one and detection of CD 33+ and CD 13+ cells after culture in the other cALL sample.