The CD28 gene helps switch on T cells, the white blood cells that coordinate immune responses, and supports their survival after they recognize a threat. If it does not work properly, immune responses may be weaker or less well balanced, which can affect how the body handles infections and immune regulation. This gene plays an important role in how immune cells communicate. Public attention turned briefly to the CD28 gene after the 2006 TGN1412 trial, when an experimental antibody targeting CD28 triggered an extreme immune reaction in volunteers.
What is a gene?
Genes are pieces of DNA that hold instructions cells use to make molecules or regulate activities in the body. Some genes provide the directions for producing proteins, which are the parts of cells that do the work. Others are used mainly to manage when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body grows and works, and they can also influence your response to food, stress, and medicines. For a deeper look at this topic, more information is available in the LearnHub.
Overview
CD28Gene function
What if the gene works
The CD28 gene helps control how T cells switch on when they detect germs or other threats.
Its protein gives a needed second signal that supports immune responses, cell survival, and immune memory.
Risk
What if the gene does not work
More severe variants in the CD28 gene can cause a primary immune condition with poor T cell activation, leading to repeated infections, skin warts, or low antibody levels. Milder variants may reduce immune signaling with a broader range of symptoms.
Treatment
What does that mean for your treatment
No CD28-specific treatment or management approach is currently established for pathogenic or loss of function variants in the CD28 gene. The CD28 gene is part of an immune signaling pathway targeted by some cancer and autoimmune therapies, so it is being studied as a drug target and biomarker, but this has not led to variant-specific drug choices.
Conditions associated with CD28
Gene function
What if the gene works
Your immune system uses the CD28 gene to help T cells respond in a controlled, effective way. When a T cell notices a germ or another threat, signals from the CD28 gene help turn that first recognition into a fuller immune response. Understanding what the CD28 gene does in the immune system helps show how your body builds a measured defense.
The CD28 gene gives T cells an important second signal after they recognize a target. This added cue helps the cell move from early detection to a more complete immune response.
Its protein sits on the surface of T cells and binds partner proteins on immune cells that present a threat. This contact helps confirm that the T cell should respond.
Signals from the CD28 gene help T cells make cytokines (immune messenger proteins). These messages help nearby immune cells work together in a coordinated way.
The CD28 gene supports T cell growth and division after activation. This helps your body build enough responder cells during an immune response.
What is a variant?
A genetic variant is a small difference in the DNA sequence of a gene. These changes are common and help shape normal human diversity, such as differences in appearance, metabolism, or the way the body responds to environmental influences. Many variants have no noticeable effect and simply represent natural genetic variation. In some cases, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the CD28 gene can change immune cell signaling by reducing how much of the CD28 protein reaches the cell surface or by weakening its contact with partner proteins. Milder variants may only dampen signaling, while more disruptive variants can markedly reduce protein stability, shorten its lifespan in the cell, or block key signaling steps. Some changes may also affect how the receptor clusters at the cell membrane, which can further limit downstream activation signals.
How variants are linked to conditions
Information on CD28 gene variants linked to conditions centers on a rare inherited immune condition called CD28 deficiency. Pathogenic variants in the CD28 gene can cause this primary immunodeficiency, which may lead to repeated infections, ongoing viral illnesses such as Epstein-Barr virus infection, and sometimes enlarged lymph nodes or related blood complications. Common CD28 gene variants have also been studied in autoimmune diseases, but these links do not by themselves diagnose a condition.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are common in the general population. Most do not directly affect health and simply reflect natural human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when several genes and environmental factors play a role. In some situations, though, a single well characterized variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the CD28 gene itself. If a CD28 finding appears on genetic testing, its meaning depends a lot on the exact change and the health condition being evaluated, so personal guidance from a doctor or genetic counselor is important.
Inheritance of CD28 variants
There is not yet a broadly confirmed Mendelian pattern for how CD28 gene variants are inherited in relation to a specific inherited condition. In practice, CD28 gene inheritance follows the usual pattern for genes on the autosomes, but a clear disease specific autosomal dominant or autosomal recessive pattern has not been firmly established for inherited CD28 related conditions. The CD28 gene is located on chromosome 2, which means each person inherits one copy from each parent.
What does my CD28 result mean for my family?
There is not yet a broadly confirmed inheritance pattern tied to a specific, well-established inherited condition for the CD28 gene, and this picture may become clearer as research grows. If you have a specific CD28 result and want to understand what it could mean for your relatives, a doctor or genetic counselor can explain it in the context of your family history and the exact variant found.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a variant in the CD28 gene, a lab can analyze DNA from blood, saliva, or a cheek swab. Genetic testing for CD28 variants reads the gene's sequence and compares it with a reference to identify changes. Results may show a benign variant, an uncertain finding, or a variant linked to a health condition.
When should I consider getting a genetic test?
There isn't yet a broadly established, CD28-specific clinical reason for genetic testing in most people. Testing decisions are usually based on the full picture, including your symptoms, family history, and whether a doctor or genetic counselor thinks broader genetic testing may help.
A genetic result is only one part of your health story
A genetic finding can provide valuable information, but how much it reveals depends on the condition and the type of variant present. Over time, the way the body works is also shaped by factors such as lifestyle, environment, age, and medical history. In some conditions, especially those influenced by many genes, genetic information provides context rather than certainty and is best considered together with other parts of care. In other situations, a genetic result can offer a clear answer. In areas like medication response, genetic results can also help put personal experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Some people break down a drug more slowly or more quickly, while others may be more or less sensitive to its effects. This helps explain why the same treatment can work well for one person, have less benefit for another, or cause more side effects in someone else. These differences are common and are one part of why medication response can vary from person to person.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes can affect their response to medications. It studies links between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes influence both how strongly a drug works and how the body handles it. This information can support treatment decisions that are better informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the CD28 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding everyday medication choices. Questions about side effects, how well a medicine is working, or possible treatment changes are best discussed with your doctor.
History
The CD28 gene entered immunology research as scientists worked out how T cells need more than one signal to fully respond. In recent decades, awareness of this gene’s role has grown as laboratory studies showed CD28 was central to that second activating signal. From these first observations, research expanded steadily into transplant medicine, autoimmunity, and cancer immunotherapy. CD28 also became widely discussed after the 2006 TGN1412 clinical trial, in which a drug aimed at this pathway caused life threatening immune reactions in healthy volunteers. That event changed how early immune drug trials are designed and monitored. These historical steps shaped today’s understanding of CD28 as a major landmark in modern immune research.