Cluster of differentiation 80 and Cluster of differentiation 86 co-stimulatory molecules (CD80/CD86)

Molecular Classification

Receptor ligand (co-stimulatory molecule), Immunoglobulin superfamily protein, Cell surface glycoprotein

Other Names

B7-1 (for CD80), B7-2 (for CD86), B7 family co-stimulatory molecules, Costimulatory ligands/receptors

Disease Roles

Cancer (immunotherapy target, tumor immune evasion)Inflammation/autoimmune disease (e.g., asthma, transplant rejection)Infection (regulation during viral infections such as EBV)

Cluster of differentiation 80 and Cluster of differentiation 86 co-stimulatory molecules Overview

CD80 and CD86 are closely related cell surface glycoproteins belonging to the immunoglobulin superfamily. They are primarily expressed on professional antigen-presenting cells such as dendritic cells, activated B-cells, macrophages, and some activated T-cells. Both function as critical co-stimulatory ligands required for full T-cell activation. They bind two key receptors on T-cells: * **CD28**, which delivers a positive signal promoting T-cell proliferation, cytokine production, survival, and effector function; * **CTLA‑4**, which delivers an inhibitory signal dampening immune responses. The balance between these signals is essential for effective immunity while preventing autoimmunity. Both proteins play central roles in transplant rejection, allergy/asthma pathogenesis, anti-tumor immunity regulation, infectious disease responses—including Epstein-Barr virus—and tolerance induction. Therapeutically targeting this axis has led to approved biologics like abatacept/belatacept that inhibit co-stimulation by mimicking CTLA‑4 binding; conversely checkpoint inhibitors like ipilimumab block inhibitory signaling through CTLA‑4. The expression pattern and functional state of these molecules can be used as biomarkers in clinical settings. Structurally: * **CD80/B7–1:** Type I transmembrane protein (~33 kDa), predominantly forms dimers; higher affinity binding than CD86; upregulated upon stimulation by various cytokines/LPS. * **CD86/B7–2:** Constitutively expressed at low levels but rapidly upregulated after APC stimulation; binds same receptors but with different kinetics compared to CD80.

Mechanism of Action

Drugs targeting these molecules typically: - Block or modulate the interaction between CD80/CD86 on antigen-presenting cells and their receptors on T cells—CD28 for activation or CTLA‑4 for inhibition. - Inhibit costimulation to suppress unwanted immune responses in autoimmunity or transplantation. - Enhance costimulation to boost anti-tumor immunity in cancer therapy.

Biological Functions

Immune response modulation

T cell activation and inhibition

Co-stimulation of T lymphocytes

Regulation of self-tolerance and immune homeostasis

Disease Associations

Cancer (immunotherapy target, tumor immune evasion)

Inflammation/autoimmune disease (e.g., asthma, transplant rejection)

Infection (regulation during viral infections such as EBV)

Safety Considerations

Risk of over-suppression leading to infection or malignancy when blocking costimulation.
Risk of excessive immune activation leading to autoimmunity when enhancing costimulation.
Therapeutic manipulation must balance efficacy with risk for immune-related adverse events.

Interacting Drugs

Abatacept (CTLA4-Ig fusion protein)

Belatacept (CTLA4-Ig variant for transplantation)

Ipilimumab indirectly affects the pathway via CTLA‑4 blockade

Associated Biomarkers

Biomarker
Expression levels of CD80/CD86 on antigen-presenting cells can serve as biomarkers for: Immune activation status
Predicting response to immunotherapies targeting the CTLA‑4/B7 axis