CD86

File:CTLA4 Diagram.png

Diagram illustrating the interaction between CD86 and CTLA-4.

CD86 is a protein expressed on the surface of antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells. It plays a crucial role in the immune system by providing necessary signals for the activation of T cells. CD86 is a member of the B7 family of proteins and is also known as B7-2.

Structure

CD86 is a type I transmembrane protein that belongs to the immunoglobulin superfamily. It consists of an extracellular domain, a transmembrane domain, and a short cytoplasmic tail. The extracellular domain is responsible for binding to its ligands, CD28 and CTLA-4, on T cells.

Function

CD86, along with CD80 (B7-1), provides the second signal necessary for T cell activation. The first signal is provided by the interaction of the T cell receptor (TCR) with the major histocompatibility complex (MHC) presenting an antigen. The binding of CD86 to CD28 on T cells delivers a costimulatory signal that promotes T cell proliferation, survival, and cytokine production.

Conversely, the interaction of CD86 with CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) delivers an inhibitory signal that downregulates T cell responses. This balance between activation and inhibition is crucial for maintaining immune homeostasis and preventing autoimmunity.

Clinical Significance

CD86 is a target for therapeutic interventions in various autoimmune diseases, transplant rejection, and cancer. Modulating the CD86 pathway can enhance or suppress immune responses, depending on the clinical context. For instance, blocking the interaction between CD86 and CTLA-4 can enhance anti-tumor immunity, while promoting this interaction can help in treating autoimmune conditions.

Related Pages

• CD80
• CTLA-4
• CD28
• Antigen-presenting cell
• Immune system