Chemotherapy is a crucial treatment for patients with acute myeloid leukemia (AML), with bone marrow suppression as the most common toxic side effect. The development, proliferation, and differentiation of various types of blood cells are regulated by a variety of hematopoietic factors. However, it is not clear whether there is a difference in the expression level of hematopoietic factors after chemotherapy in patients with AML at different altitudes and the change pattern has not been clarified.

To investigate whether there are differences in the expression levels of hematopoietic factors in bone marrow and serum before and after chemotherapy and their changes in patients with AML at varying altitudes.

A total of 28 AML patients (non-M3 type) treated for the first time in the Department of Hematology at Qinghai Provincial People's Hospital (1 501 to 2 500 m in the middle altitude area) and the Department of Hematology of Xi-Jing Hospital, Air Force Medical University of PLA (500 to 1 500 m in low altitude area) from 2021 to 2022 were selected as the research subjects, and according to the altitude of the hospitals they visited, the AML patients were divided into the middle altitude group (13 cases) and the low altitude group (15 cases). The WHO grading criteria for acute and subacute toxicity of anticancer drugs was used to evaluate the myelosuppressive scores of the patients on days 8, 14, and 28 of chemotherapy. The expression levels of erythropoietin (EPO), FMS-like tyrosine kinase 3 ligand (Flt3-L), thrombopoietin (TPO), and interferon γ (IFN-γ) in serum and bone marrow before chemotherapy and on day 8, day 28 of chemotherapy were detected and compared by enzyme-linked immunosorbent assay.

On days 14 and 28 of chemotherapy, the myelosuppressive scores of patients in the low-altitude group were higher than those in the middle-altitude group (Z=-1.975, P=0.048; Z=-2.049, P=0.040). On day 28 of chemotherapy, the serum and bone marrow EPO expression levels in the low-altitude group were higher than those in the middle-altitude group (P<0.05), the serum EPO expression level on day 28 of chemotherapy was lower than that on day 8 of chemotherapy, and the difference was statistically significant (P<0.05). On day 28 of chemotherapy, the serum and bone marrow expression levels of Flt3-L were higher in the low-altitude group compared to the middle-altitude group (P<0.05) ; the serum Flt3-L expression levels on day 8 and day 28 of chemotherapy were higher than those before chemotherapy in both groups, the bone marrow Flt3-L expression level on day 28 of chemotherapy was higher than that before chemotherapy in both groups (P<0.05). The serum TPO expression levels in the low-altitude group were higher than those in the middle-altitude group before chemotherapy, on the day 8 day 28 of chemotherapy (P<0.05) ; the serum TPO expression level in the low-altitude group was lower than that before chemotherapy on the day 8 of chemotherapy (P<0.05) ; the bone marrow TPO expression level in the low-altitude group was higher than that in the middle-altitude group on the day 28 of chemotherapy (P<0.05) ; the expression level of bone marrow TPO in the middle-altitude group on the day 28 of chemotherapy was lower than that before chemotherapy (P<0.05). There was no significant difference in serum and bone marrow IFN-γ expression levels between and within the two groups before and after chemotherapy (P>0.05) .

The expression levels of haemopoietic factors including EPO, Flt3-L, and TPO were higher during the recovery of myelosuppression after chemotherapy in AML patients at low altitude, compared to those at middle altitude. There was no significant difference between the two groups in terms of the hematopoietic inhibitory factor IFN-γ. Myelosuppression grades and degree after chemotherapy are more severe in AML patients at middle altitude than at low altitude.