Butyrophilin-like protein (BTNL)

Butyrophilin-like (BTNL) proteins are a family of transmembrane molecules within the immunoglobulin superfamily that are structurally related to the B7 family of costimulatory proteins (UniProt: Q969G3). They function as critical regulators of immune homeostasis, primarily by modulating the activity and differentiation of T-cell subsets (PubMed: 31439606). For instance, Butyrophilin-like protein 2 (BTNL2) acts as a co-inhibitory signal that suppresses T-cell proliferation and cytokine production, and its genetic variants are strongly linked to inflammatory diseases such as sarcoidosis and ulcerative colitis (PubMed: 15107855). Other members, like the BTNL3 and BTNL8 heteromer, are specifically expressed in the intestinal epithelium where they mediate the selection and maintenance of intraepithelial gamma-delta T cells (PubMed: 31439606). In the context of oncology, several BTNL proteins are frequently downregulated in tumors, suggesting they may play a role in immune evasion and could serve as targets for checkpoint inhibition or agonist therapy (PubMed: 19155474). Current therapeutic development focuses on monoclonal antibodies and recombinant fusion proteins aimed at either restoring inhibitory signals in autoimmune conditions or blocking them to enhance anti-tumor immunity.

Other names

Butyrophilin-like familyBTN-like proteinB7-like proteinBTNL

BTNL proteins modulate immune responses by interacting with receptors on T cells to either attenuate or enhance T-cell activation and proliferation (PubMed: 15107855, PubMed: 31439606).