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This response involves the interaction of T cells, monocytes, and macrophages. This reaction is caused when CD4 + T h 1 cells recognize foreign antigen in a complex with the MHC class II on the surface of antigen-presenting cells. These can be macrophages that secrete IL-12, which stimulates the proliferation of further CD4 + T h 1 cells.
T cells are called T cells because they mature in the thymus. The two types of T cells that cause damage to tissues in type IV hypersensitivity are CD8+ T cells also known as killer T cells or cytotoxic T cells, as well as CD4+ T cells also known as helper T cells. CD8+ killer T cells do exactly what their name implies - they kill things.
In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as helper T cells , monocytes , macrophages , and dendritic cells .
The T helper cells (T h cells), also known as CD4 + cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines .
The CD family of co-receptors are a well-studied group of extracellular receptors found in immunological cells. [4] The CD receptor family typically act as co-receptors, illustrated by the classic example of CD4 acting as a co-receptor to the T cell receptor (TCR) to bind major histocompatibility complex II (MHC-II). [5]
Cytolitic activity: Tr1 cells can both express Granzyme A and granzyme B. It was shown recently, that Tr1 cells, in vitro and also ex vivo, specifically lyse cells of myeloid origin, but not other APC or T or B lymphocytes. [14] Cytolysis indirectly suppresses immune response by reducing numbers of myeloid-origin antigen presenting cells.
This discovery furthered the development of a previously hypothesized theory, the immunosurveillance theory. The immunosurveillance theory suggests that the immune system routinely patrols the cells of the body, and, upon recognition of a cell, or group of cells, that has become cancerous, it will attempt to destroy them, thus preventing the growth of some tumors.
The sensitization phase where the hapten is applied to the skin for the first time is characterized by the activation of innate immune responses, including migration of dendritic cells to the lymph nodes, priming antigen-specific naive T cells, and the generation of antigen-specific effector or memory T cells and B cells and antibody-secreting ...