Trem-like transcript 2 protein, also known as Triggering receptor expressed on myeloid cells-like protein 2, TREML2 and TLT2, is a single-pass type I membrane protein that contains one Ig-like V-type (immunoglobulin-like) domain. TREML2 is detected in cultured B cells, T cell leukemia and monocyte leukemia. TREML2 is expressed constitutively on CD8 T-cells and induced on CD4 T-cells after activation. TREML2 is a cell surface receptor that may play a role in the innate and adaptive immune response. TREML2 acts as a counter-receptor for CD276 and interaction with CD276 on T-cells enhances T-cell activation. Murine B7-H3 is specifically bound to Triggering receptor expressed on myeloid cells (TREM)-like transcript 2 (TLT-2, TREML2). TREML2 was expressed on CD8(+) T cells constitutively and on activated CD4(+) T cells. Stimulation with B7-H3 transfectants preferentially up-regulated the proliferation and IFN-gamma production of CD8(+) T cells. Transduction of TREML2 into T cells resulted in enhanced IL-2 and IFN-gamma production via interactions with B7-H3. There may be a direct interaction between B7-H3 and TREML2 that preferentially enhances CD8(+) T cell activation.