ICT (Information Communications Technology) is a term widely used in the context of education. Even though there is no universally accepted definition for ICT, it mainly refers to utilizing digital technologies such as computers, television, email, etc to help individuals or organizations to use information.
Type IV (called also delayed hypersensitivity) involves sensitized T lymphocytes that react with cell bound or associated antigen and release lymphokines, causing mononuclear cell accumulation, tissue damage and inflammation, typically manifesting at least 24 hours after exposure to the antigen.
They are also termed type IV hypersensitivity reactions. Delayed hypersensitivity is a major mechanism of defense against various intracellular pathogens, including mycobacteria, fungi, and certain parasites, and it occurs in transplant rejection and tumor immunity.he central role of CD4 + T cells in delayed hypersensitivity is illustrated in patients with AIDS. Because of the loss of CD4 + cells, the host response against intracellular pathogens such as Mycobacterium tuberculosis is markedly impaired. The bacteria are engulfed by macrophages but are not killed.