Flow cytometry using the monoclonal antibody CD10-Pe/Cy5 is a useful tool to identify follicular lymphoma cells

Follicular lymphoma (FL) is a specific entity defined by characteristic histology, phenotype and molecular rearrangements. Classically, reactivity for CD19, CD10, and strong positivity for the surface light chain immunoglobulin (SIg) are considered to be phenotypic signs typically expressed in FL. In practice, this pattern is difficult to identify since most neoplastic cells analysed by flow cytometry (FC) show weak intensity for CD19-Pe/Cy5 and for SIg and negativity for CD10-FITC. We used triple antigen combinations including two monoclonal antibodies (MoAbs) against CD10 (CD10-FITC and CD10-Pe/Cy5) and a long-distance polymerase chain reaction (PCR) approach to establish the phenotypic pattern of neoplastic cells carrying t(14;18)(q32;q21). Neoplastic cells showed the following immunophenotype: stronger reactivity against CD20 than against CD19, positivity for CD22 and SIg and negativity for CD5, CD11c and CD10-FITC. Characteristically, CD10-Pe/Cy5 was expressed in all the samples with positive bcl-2/JH rearrangements. In FL, there was a high correlation between histologic diagnosis and reactivity against CD10-Pe/Cy5 (96% cases). In diffuse large cell lymphomas (DLCL), CD10-Pe/Cy5 identified positive cases with t(14;18)(q32;q21) chromosomal translocation, whereas Burkitt lymphomas showed all cases reactivity against CD10-Pe/Cy5. In conclusion, CD10-Pe/Cy5 is a useful antibody for identifying neoplastic cells carrying t(14;18)(q32;q21) in FL and DLCL. In combination with other MoAbs, anti-CD10 (HI10a, Cy-Chrome) can be used to identify a characteristic phenotypic profile of FL against other lymphoproliferative disorders.