Enables signaling receptor binding activity. Involved in several processes, including defense response to other organism; negative regulation of T cell anergy; and positive regulation of activated T cell proliferation. Located in cell surface. Used to study adult T-cell leukemia and bronchiolitis obliterans. Biomarker of asthma; corneal disease; middle cerebral artery infarction; and orchitis. Human ortholog(s) of this gene implicated in several diseases, including Henoch-Schoenlein purpura; autoimmune disease (multiple); chronic lymphocytic leukemia; chronic obstructive pulmonary disease; and systemic scleroderma. Orthologous to human CD86 (CD86 molecule). [provided by Alliance of Genome Resources, Apr 2022]