T SPOT

T-SPOT™ Technology

T-Cell Immunology
Over the past 20 years, there has been a growing realisation of the importance of T-cells, rather than just antibodies in controlling disease.
T-cells are now known to be critical governors of the body's immune response to pathogens and as such give a unique way to examine disease: for diagnosis, prognosis and treatment monitoring.

The Cellular Immune Response
The body has two branches of its adaptive immune response: the humoral and cellular immune response. The humoral immune system consists of antibodies, produced by B-cells that are designed to bind to, and therefore neutralise, foreign organisms invading the bloodstream. Antibodies are very important in the protection of humans against disease, and the production of antibodies is the basis of the protection afforded by almost every vaccine currently used.

The other branch of the immune response is called the 'cellular immune response', which is primarily made of T-cells. Unlike antibodies, T-cells are not necessarily confined to the bloodstream and can attack pathogens wherever they may be in the body. Recent discoveries in immunology have enabled us to classify these T-cells into two groups: effector T-cells and memory T-cells.

Memory Cells
Memory T-cells carry the body's long-term immunity or 'memory' of an infection-causing pathogen and are present after any infection. Memory cells are generally not able to fight the infection directly, but they enable the body to react quickly and control the pathogen if encountered later in life. These cells have a long life and are present in small numbers, circulating around the body acting as sentinels for infection. On re-encountering a pathogen, memory cells rapidly send messenger molecules, known as cytokines. These cytokines attract further cells to the area that initiate proliferation of the memory cells through cell division, producing an army of effector T-cells.

Effector Cells
Effector T-cells fight the pathogen directly and come in various forms, designed to kill different pathogens in different ways. Most are short-lived and die off when the pathogen is cleared from the body, however a small subset are programmed to become memory cells, ensuring that the body is again protected against future re-infection.

Due to the short life of effector T-cells, their continuing presence indicates the cellular immune response is currently encountering and fighting a pathogen somewhere in the body. Measuring the presence of effector T-cells in a sample therefore diagnoses an ongoing infection. (In contrast, the presence of memory T-cells, for example, would only indicate that someone had been infected with the pathogen at some point in the past).

Further, measuring how the levels of effector T-cells change over time illustrates how well the body is coping with the infection, giving potential indications on disease prognosis. Finally, since effector T-cells die off when the pathogen has been cleared from the body, monitoring the levels of the effector T-cells over time and seeing whether they drop to zero could identify whether the body has been successful in clearing the infection; that is, whether the patient is cured. The T-SPOT™ technology is a revolutionary new method to detect and quantify these effector T-cells.