cis-B7:CD28 interactions at invaginated synaptic membranes provide CD28 co-stimulation and promote CD8+ T cell function and anti-tumor immunity (2023)


CD28 is a co-stimulatory receptor expressed on all mouse and human Tcells at birth that regulates Tcell receptor (TCR) responses both quantitatively and qualitatively.1,2,3,4 Aging-associated loss of CD28 in human Tcells is correlated with compromised immune responses to pathogens.5,6,7 Aberrant CD28 signaling is a defining feature of Tcell dysfunction in cancer, autoimmunity, and viral infection.8,9,10 Although earlier work suggested that CD28 is more important for CD4+ Tcells, its significance in CD8+ Tcells is being increasingly recognized, including priming naive CD8+ Tcells and regulating effector and memory CD8+ Tcells.11,12,13

CD28 has two ligands, B7-1 (CD80) and B7-2 (CD86), best known to be expressed on professional antigen-presenting cells (APCs).14 B7:CD28 trans-interactions in the secondary lymphoid organs trigger critical signal 2 alongside TCR ligation that promotes Tcell proliferation, survival, migration, and cytokine production.3 However, B7 ligands can be limited in peripheral tissues due to the general lack of B7 expression on non-immune cells, raising the questions of whether and how CD28 co-stimulation might occur in peripheral tissues. B7 ligands are also displayed by Tcells, either through translation of Tcell-intrinsic CD80 and CD86 mRNAs or trogocytosis, a process by which Tcells acquire membrane proteins from APCs upon physical contact.15,16,17,18 In mice with experimental autoimmune encephalomyelitis, Tcells are the main B7-expressing cells in pathological tissues.19 However, the physiological significance of Tcell B7 is unclear.

Here, we hypothesized that CD28 can interact with B7 in cisonthe same Tcell surface/membrane for co-stimulation. We determined the existence, topological requirement, subcellularlocalization, and physiological consequence of cis-B7:CD28 interactions.We provide evidence that cis-B7:CD28 signaling occurs at invaginated synaptic membranesand promotes anti-tumor activity of effector CD8+ Tcells.

Section snippets

A subpopulation of CD8+ Tcells co-express CD28 and B7 ligands

In light of previous reports of B7 expression by Tcells,15,18,20 we used flow cytometry to measure CD80 and CD86 surface expression kinetics on OT-1 transgenic CD8+ Tcells primed by ovalbumin peptide 257–264 (OVA257–264). CD80 and CD86 were expressed on a subset of naive OT-1 cells and elevated upon peptide stimulation. The frequency of CD28+CD80+ and CD28+CD86+ OT-1 cells reached 82% and 71%, respectively (Figure1A; see FigureS1 for gating strategy). Thus, CD8+ Tcells co-express CD28 and


In the current paradigm, CD28 is activated in trans by B7 ligands expressed on professional APCs in secondary lymphoid organs.3,4,59 Here, we showed that B7 ligands displayed by primed Tcells activated CD28 in cis at negative curvatures of the IS, leading to Tcell-autonomous co-stimulation that enhanced cytokine production, survival, migration, and anti-tumor activity of primed CD8+ Tcells.

Effector cells typically require less CD28 co-stimulation than naive cells, but our results suggest a

Key resources table

PE anti-human CD28 antibodyBioLegendCat # 302940
RRID: AB_2564147
Anti-human CD28 antibodyBio X CellCat # BE0291
RRID: AB_2687814
PE anti-human CD80 antibodyBioLegendCat # 305208
RRID: AB_314504
Allophycocyanin anti-human CD80 antibodyBioLegendCat # 305220
Allophycocyanin anti-human CD86 antibodyBioLegendCat # 374207
RRID: AB_2721448
CF568 anti-mouse IgG antibodyBiotiumCat # 20802
Anti-human CD3ε antibodyBioLegendCat # 317326
RRID: AB_11150592


We thank E. Griffis (Nikon Imaging Center of UCSD) for help with STORM imaging, J. Sabatini (UCSD School of Medicine Microscopy Core, supported by NIH grant P30 NS047101) for help with confocal microscopy, J. Wilhelm (UCSD) and N. Stuurman (UCSF) for support with TIRF microscopy, M. Rose (Tissue Technology Shared Resource of UCSD, supported by NIH grant P30 CA23100) for help with histological experiments, G. Castillon and Y. Jones (UCSD Cellular and Molecular Medicine Electron Microscopy Core,

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What is the interaction between B7 and CD28? ›

The interaction of CD28 with one of the B7 molecules (CD80 and CD86) on professional antigen-presenting cells (APC) is generally considered as the most important co-stimulatory signal for T cell activation. APC in a resting condition express either no or only low levels of B7 molecules.

What is CD28 B7? ›

B7 is a type of integral membrane protein found on activated antigen-presenting cells (APC) that, when paired with either a CD28 or CD152 (CTLA-4) surface protein on a T cell, can produce a costimulatory signal or a coinhibitory signal to enhance or decrease the activity of a MHC-TCR signal between the APC and the T ...

Is CD28 a glycoprotein? ›

CD28 is a cell surface glycoprotein expressed on T cells that modulates immune responses through its ability to transduce costimulatory signals.

How does CD28 prevent autoimmune disease? ›

Treg cells are negative regulators of T-cell signaling and contribute to T-cell anergy and to the maintenance of self-tolerance by suppressing autoreactive T cells 14. Therefore, CD28 can either reduce or enhance the susceptibility to autoimmune diseases by altering T-cell effector and Treg cell compartments.

What does CD28 activation do? ›

CD28 binds to multiple signaling proteins that interact with multiple downstream pathways. In one example, CD28 binding and activation of PI3K activate numerous signaling proteins that carry pleckstrin homology (PH) domains (i.e., 60+ proteins).

What is the function of B7 in the immune system? ›

The B7 family consists of structurally related, cell-surface protein ligands, which bind to the CD28 family of receptors on lymphocytes and regulate immune responses via 'costimulatory' or 'coinhibitory' signals.

What drug blocks CD28? ›

Abatacept (CTLA-4–immunoglobulin) blocks CD28 costimulation on T cells and has been shown to halt progression of nephritis in lupus-prone mice, especially when combined with CYC. An RCT compared two different doses of abatacept against placebo in 298 patients with class III-IV lupus nephritis.

What are B7 and CD28 families? ›

The B7/CD28 families consists of three groups based on their phylogeny (Fig. 1): group I consists of CD28/CTLA-4/B7-1/B7-2 and ICOS/ICOS-L (B7h); group II consists of PD-1/PD-L1/PD-L2; and group III consists of TMIGD2/KIR3DL3/HHLA2, B7-H3, and B7x (B7-H4/B7S1/VTCN1) [3,4,5,6].

What diseases have CD28? ›

Diseases associated with CD28 include Mycosis Fungoides and Sezary's Disease. Among its related pathways are CD28 co-stimulation and PI5P, PP2A and IER3 Regulate PI3K/AKT Signaling. Gene Ontology (GO) annotations related to this gene include identical protein binding and obsolete SH3/SH2 adaptor activity.

What immune cells express CD28? ›

The CD28 receptor is stimulated during the contact of T cells with antigen-presenting cells. A counter-receptor for CD28 is the B7 molecule expressed on activated B cells, dendritic cells, and macrophages. B7 also binds to CTLA-4, a receptor that is structurally related to CD28.

What does anti CD28 mean? ›

The molecular properties of superagonistic anti-CD28 antibodies allow the generation of a strong activating signal in mature T cells, including Treg cells, without additional stimulation of the T cell receptor complex.

Which vitamin deficiency causes autoimmune disease? ›

Vitamin D insufficiency has been linked to autoimmune disorders that commonly display significant differences between females and males due to genetic, epigenetic, hormonal, and environmental factors. Notably, a number of studies recently showed a cross-talk between vitamin D and the sex hormone estrogen.

What is the trigger factor of autoimmune disease? ›

The exact cause of autoimmune disorders is unknown. One theory is that some microorganisms (such as bacteria or viruses) or drugs may trigger changes that confuse the immune system. This may happen more often in people who have genes that make them more prone to autoimmune disorders.

Which vitamin prevent autoimmune disease? ›

Vitamin D supplements really do reduce risk of autoimmune disease (New Scientist) Taking Vitamin D Daily Can Help Prevent This Disease, New Study Says (Eat This, Not That!) Taking vitamin D and omega-3 fish oil supplements every day cuts your risk of developing arthritis by 22%, study suggests (Daily Mail)

Is CD28 an antibody? ›

The anti-T cell monoclonal antibody 9.3 (anti-CD28) provides a helper signal and bypasses the need for accessory cells in T cell activation with immobilized anti-CD3 and mitogens.

Do memory T cells need CD28? ›

Semin Immunol.

Who is most at risk for vitamin B7 deficiency? ›

These include:
  • People with biotinidase deficiency. This rare hereditary disorder prevents the body from reusing biotin. ...
  • Pregnant women. Biotin is critical for pregnant women. ...
  • People using certain medications. Antibiotics can destroy the healthy bacteria in your intestines. ...
  • People using IV feeding.
Jun 28, 2017

Who is at risk of vitamin B7 deficiency? ›

Who is at risk for biotin deficiency? People with health conditions that impact how the body absorbs nutrients, or who are on certain medications, can be at risk of developing biotin deficiency. Biotinidase deficiency (BTD) is the most common cause of biotin deficiency.

What happens if you don't have enough vitamin B7? ›

Biotin deficiency is very rare in the United States. Biotin deficiency can cause thinning hair and loss of body hair; a rash around the eyes, nose, mouth, and anal area; pinkeye; high levels of acid in the blood and urine; seizures; skin infection; brittle nails; and nervous system disorders.

What drugs inhibit T cells? ›

Cyclosporin A and tacrolimus inhibit T-cell proliferation in response to either specific antigens or allogeneic cells and are used extensively in medical practice to prevent the rejection of allogeneic organ grafts.

What is the role of CD28 in T cells? ›

The CD28 molecule acts as a major costimulatory receptor in promoting full activation of naive T cells. However, despite extensive studies, why naive T cell activation requires concurrent stimulation of both the TCR and costimulatory receptors remains poorly understood.

How a deficiency in CD28 could result in severe disease during an infection? ›

This study demonstrates that CD28 deficiency results in the generation of germinal-center independent IgM+ experienced B cells and the production of protective IgM during experimental malaria, providing evidence for an additional mechanism by which the immune system controls Plasmodium infection.

How long does it take to stimulate T cells? ›

Incubate culture plate for 1–3 days in 5% CO2 incubator at 37°C. By day 1, cells will produce transcription factors and cytokines. Most T cells will require up to 3 days to divide.

What does CD28 interact with? ›

CD28 is a homodimeric type 1 transmembrane protein that is a member of the immunoglobulin (Ig) superfamily and has a single Ig-like domain. CD28 interacts with CD80 (also known as B7-1) and CD86 (B7-2), which are expressed on the APC in response to activating signals that result from, for example, CD40 engagement.

Which checkpoint molecule works by preventing B7 CD28 interaction? ›

B7 homolog 3 protein (B7-H3) also known as CD276 is an immune checkpoint molecule that belongs to the B7-CD28 family and was discovered in 2001 (5). This molecule has been associated with costimulatory as well as coinhibitory functions in regulating T cell responses.

What binds to CD28? ›

CD28 can be bound by the ligands CD80 and CD86 (B7-1 and B7-2) presented by APCs. If the TCR binds a target without CD28 binding one of these two ligands, co-stimulation will not occur, and the T-cell will be anergic. CD28 is also expressed in high concentration, but is a low affinity receptor.

What are the members of the CD28 family? ›

The CD28 family of receptors (CD28, cytotoxic T-lymphocyte–associated antigen 4 [CTLA-4], inducible costimulator [ICOS], program death-1 [PD-1], and B- and T-lymphocyte attenuator [BTLA]) plays a critical role in controlling the adaptive arm of the immune response.

What happens to at cell if CD28 and CD80 86 do not interact? ›

The absence of either CD40L-CD40 or CD28-CD80/86 interactions results in a loss of thymic NKT cells, while not as severe as that observed in CD40/CD80/86 KO mice, is profound.

How can I improve my T cell function? ›

How To Boost Your Immune System
  1. Get some sun. The same t-cells that benefit from sleep form part of the body's response to viruses and bacteria, and one of the key ingredients that 'primes' those t-cells for action is vitamin D. ...
  2. Reach for vitamin C foods. ...
  3. Incorporate garlic in your diet.
Apr 12, 2020

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