Chemotherapy resistance in acute myeloid leukemia is associated with decreased anti-tumor immune response through MHC molecule and B7 family members

Acute myeloid leukemia (AML) remains challenging due to chemotherapeutic drug-resistance (CDR). Aberrant expression B7 family proteins are involved in tumors evasion. We wonder whether B7 family protein alteration in AML CDR further supports tumor escape. Here, we establish AML cytarabine-resistant cell line U937/Ara-C and report on the expression MHC molecule and B7 family member. HLA-ABC was highly expressed similarly on both cell lines. MIC (MHC class I chain related) A/B and B7-H6 was moderately expressed on the surface of U937 and decreased dramatically by U937/Ara-C. In contrast, enhanced expression of B7-H1 and B7-H7 by U937/Ara-C was observed. HLA-DR and other B7 family members including CD80, CD86, B7-DC, B7-H2, B7-H3, B7-H4, and B7-H5 were not detected by both cell lines. Compared co-cultured with U937, peripheral blood mononuclear cells showed a decreased cytotoxicity when incubated with U937/Ara-C, as indicated by decreased levels of granzyme B and perforin production, accompanied with less TNF-alpha and lactate dehydrogenase secretion. In conclusion, AML CDR further evades the anti-tumor immune response which may through MHC molecule and B7 family members.