Clinical correlation of circulating heat shock protein 70 in acute leukemia

The heat shock protein 70 (HSP70) is one of the molecular chaperone family involved in the protection of cells upon exposure to various types of stresses. Plasma circulating HSP70 (cHSP70) is believed to play a role in the anti-tumor immune responses and its levels may reflect the levels of severity or the disease condition. Using electrochemiluminescence protein detection immunoassay, we measured the cHSP70 levels in the plasma of patients with acute myeloid leukemia (AML) (n = 96), myelodysplastic syndrome (MDS) (n = 28), and acute lymphoblastic leukemia (ALL) (n = 40) and compared with those in normal individuals (n = 99). cHSP70 levels were significantly higher in AML (median: 10.71 ng/mL, range: 1.93–79.0 ng/mL) and ALL (median: 27.59 ng/mL, range: 5.09–129.6 ng/mL) as compared to those in MDS (median: 4.54 ng/mL, range: 1.35–58.3 ng/mL) or healthy controls (median: 4.13 ng/mL, range: 1.75–13.6 ng/mL). Levels of cHSP70 showed significant positive correlation with lactate dehydrogenase (LDH) and white blood cells (WBC) in AML and ALL patients, which may reflect overall tumor load. Furthermore, patients with higher levels of cHSP70 had significantly shorter survival in AML (P = 0.04) and ALL (P = 0.05), suggesting that in these two acute diseases, cHSP70 is an indicator for poor prognosis. Our data support the potential of using free cHSP70 as a biomarker in leukemias and potentially other types of cancers.