Soluble CD44 and CD44v6 and prognosis in children with B-cell acute lymphoblastic leukemia.

AIM

CD44v6 is an isoform of CD44 that can be present in soluble form (sCD44v6). The aim of this study is to evaluate the presence of soluble CD44 (sCD44) and sCD44v6 in serum of children with B-cell precursor acute lymphoblastic leukemia (B-ALL) and their relationship with prognosis.

METHODS

sCD44v6 and sCD44 levels were measured in the sera of patients and healthy children by enzyme-linked immunosorbent assay. The level of the molecules was analyzed in relation to laboratory and clinical characteristics of the patients at presentation and response to therapy.

RESULT

sCD44v6 was significantly lower in patients (103.4 ± 44 ng/mL) than in controls (173.5 ± 73.6 ng/mL) whereas the serum level of sCD44 showed no significant difference between the groups. In patients, sCD44v6 quantity was inversely correlated with sCD44 level (r = -0.57, P < 0.01). The mean serum level of sCD44 in patients with >20% positivity for CD44 surface expression was greater than that in patients with ≤20% positivity (1345 ± 409 ng/mL vs 1111 ± 390 ng/mL, P = 0.05). sCD44v6 showed no significant association with response to therapy and prognostic factors except the TEL/AML1 positivity, as it was higher in TEL/AML1 positive patients (157.3 ± 55.6 ng/mL) than negative ones (92 ± 43.6 ng/mL, P = 0.036). Conversely, sCD44 was lower in TEL/AML1 positive patients and showed a significant association with white blood cell number, blast percentage and extramedullary involvement.

CONCLUSION

The lower level of sCD44v6 in patients than in controls suggests the possible diagnostic value of this molecule for B-ALL. The presence of an association with established prognostic factors despite of no relationship with disease outcome suggested these molecules for more studies in larger patient cohorts.