Differential expression of TIM-3 in circulation and tumor microenvironment of colorectal cancer patients.

T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) is an inhibitory immune checkpoint, which suppresses anti-tumor immune responses. TIM-3 expression on different immune cells in periphery and tumor microenvironment (TME) of colorectal cancer (CRC) patients has not been fully investigated. We found that TIM-3 was mainly expressed on monocytic myeloid cells (MMCs) and antigen-presenting cells (APCs) in circulation but was mainly expressed on T cells and APCs in the TME. Additionally, TIM-3− T cells co-expressed higher levels of PD-1 than TIM-3+ T cells in normal tissue. In contrast, TIM-3+ T cells in the TME showed significantly higher PD-1 expression. Interestingly, there was a trend towards increased levels of TIM-3+ APCs with disease stages; however, levels of TIM-3+ T cells were decreased with disease stages in the TME. This study shows the differential expression of TIM-3 on different immune cells in circulation and TME of CRC patients, and their associations with disease stages. • High TIM-3 expression in CRC warrants characterization on immune cell populations. • TIM-3 was mainly expressed on MMCs and APCs in blood, APCs and T cells in the TME. • Unlike normal tissue, TIM-3 was co-expressed with PD-1 in tumor-infiltrating T cells. • There was a trend towards increased levels of TIM-3+ APCs with disease stages. • Levels of TIM-3+ T cells were decreased with disease stages in the TME. [ABSTRACT FROM AUTHOR]