Our FLT3 mAb with enhanced affinity to the Fc receptor CD16a termed 4G8-SDIE potently induced NK cell reactivity against FLT3-transfectants, the B-ALL cell line SEM and primary leukemic cells of adult B-ALL patients in a target-antigen dependent manner as revealed by analyses of NK cell activation and degranulation.
Immunophenotypic profile at diagnosis was consistent with B precursor ALL (CD19, CD24, CD33 positive, weak CD13 positivity, CD10 negative) and both were negative for FLT3-D835/I836 and FLT3-ITD mutations.
We identified over 1000 tyrosine phosphorylation sites from about 750 proteins in both AML (wild type and mutant FLT3) and B cell acute lymphoblastic leukemia (normal and amplification of FLT3) cell lines.
The positivity rate of FLT3 gene was significantly higher in pre-pre B-ALL/pre B-ALL subtypes (84.8%) than in B-ALL subtypes (41.7%, P<0.005), and the rate was significantly higher in B-ALL subtypes (73.3%) than in T-ALL subtypes (28.6%, P<0.001).
Our results show that the t(12;21)(p13;q22)+ ALLs display a higher intensity of CD10 (P = 0.0016) and HLADR (P = 0.005) expression together with lower levels of the CD20 (P = 0.01), CD45 (P = 0.01), CD135 (P = 0.003) and CD34 (P = 0.03) antigens as compared to the t(12;21) cases.