CD11C antigen presenting cells with high B7-H4 expression in active tuberculosis patients are associated with low stimulatory capacity to T cell proliferation.

B7-H4 is a co-inhibitory molecule that negatively regulates T lymphocytes, playing a role in immune suppression many disorders. However, the role of antigen presenting cells (APCs)-expressing B7-H4 in active pulmonary tuberculosis (ATB) remains poorly understood. Here, we demonstrated that B7-H4 expression on CD11c APCs increased in patients with ATB. B7-H4 expression on CD11c APCs was associated with high expression of HLA-DR and CD86 both in healthy controls (HCs) and in ATB patients. However, CD86 expression in B7-H4-expressing CD11c APCs was significantly lower in ATB patients compared to that in HCs. Importantly, B7-H4 expressing CD11c APCs from ATB patients showed a lower stimulatory capacity to T cell proliferation than those from HCs in mixed leukocyte culture test. Collectively, our data suggest that the evaluation of B7-H4 expression in CD11c APCs in patients with active tuberculosis might be one of the key molecular mechanisms for the dysfunction of APCs in TB patients. B7-H4 may have important implications in the prevention and treatment of patients with ATB.