Surface CD22 is a highly sensitive and specific B lineage marker and can replace cytoplasmic CD79a/cytoplasmic CD22 in flow cytometric reagent panels for the diagnosis of B-acute lymphoblastic leukemia

AbstractWorld Health Organization (WHO) guidelines, 2008 and 2016, have laid down strict criteria for assigning the lineage to blast cells in the diagnosis and classification of acute leukemia. While cytoplasmic (c) CD22 has been recommended by WHO as a strong B lymphoid lineage-associated marker along with surface (s) CD19, cCD79a, and sCD10, there is no reference to sCD22 as a diagnostic marker in these guidelines. In view of the above fact and the technological advantage surface immunophenotyping assays provide over the cytoplasmic assays, we examined the sensitivity and specificity of sCD22 for B lymphoid lineage. Blast cells in 232 cases of B-acute lymphoblastic leukemia (B-ALL) were examined by flow cytometric immunophenotyping for expression of sCD10, sCD19, sCD20, sCD22, and cCD79a in addition to a host of other lineage-associated CD markers as a part of an antibody reagent panel. In 124/126 (98%) cases of B-ALL, the blast cells expressed sCD22, thereby confirming its high sensitivity as a B lymphoid marker. In 52/54 (96%) of these cases wherein cCD79a (another B lineage marker recommended by the WHO) expression was examined in parallel, both markers were positive suggesting a very high degree of correlation between sCD22 and c79a expression. sCD22 also showed 100% specificity for the B lymphoid lineage. Our data show that sCD22 can be used as a reliable and preferred marker for the diagnosis of B-ALL in place of cCD22 and cCD79a in view of its associated technologica...
Source: Journal of Hematopathology - Category: Pathology Source Type: research