Tcellstimulering

Tcellstimulering refers to the process by which T lymphocytes, a crucial component of the adaptive immune system, are activated and begin to proliferate. This activation is a complex and tightly regulated series of events that allows T cells to recognize and respond to specific antigens. The primary mechanism for T cell stimulation involves the T cell receptor (TCR) on the surface of the T cell interacting with a peptide antigen presented by an MHC molecule on an antigen-presenting cell (APC). This interaction, known as signal 1, is essential for T cell activation.

However, for full activation and sustained immune response, a second signal, known as co-stimulation (signal 2), is also required. This signal is provided by co-stimulatory molecules on the APC, such as B7 proteins, binding to their corresponding ligands on the T cell, like CD28. Co-stimulation prevents T cell anergy, a state of unresponsiveness, and promotes proper T cell differentiation and function. Cytokines, secreted by APCs or other immune cells, can also provide a third signal (signal 3) that influences the type of T cell that develops, such as helper T cells or cytotoxic T lymphocytes.

Once stimulated, T cells undergo clonal expansion, producing a large number of identical T cells specific to the encountered antigen. These activated T cells then migrate to sites of infection or inflammation to carry out their effector functions, which include killing infected cells, helping B cells produce antibodies, and regulating immune responses. Tcellstimulering is therefore fundamental to mounting effective adaptive immunity against pathogens and maintaining immune homeostasis.