In autologous hematopoietic stem cell transplantation (autoHSCT), malignant cells remaining in the graft may re-engraft leading to relapse of the original disease. CD44 is known to play a role in the engraftment of leukemia-initiating cells and is shed from the surface of malignant cells. Soluble CD44 is a cleaved fragment, which is found in the serum of patients with metastasized epithelial and hematologic malignancies and in some other cancers, and has been demonstrated to be correlated with clinical outcome.
To investigate (1) a possible correlation between the concentration of CD44 in an autoHSCT graft and the type of hematologic malignancy and (2) a possible correlation between the concentration of CD44 in the autoHSCT graft with clinical outcome after autoHSCT.
We measured CD44 in 157 hematopoietic stem cell grafts from patients with hematologic malignancies and from 43 healthy donors by enzyme-linked immunosorbent assay.
Levels of CD44 were almost 2-fold higher in the patients' grafts. Highest levels were found in the grafts of patients with acute myeloid leukemia, diffuse large B-cell lymphoma, and plasma cell myeloma, congruent with known CD44 expression levels in these malignancies. The survival advantage among patients with CD44 levels less than 22 000 ng/mL was highly statistically significant.
These results show that CD44 levels in an autoHSCT graft may be linked to clinical outcome after autoHSCT.