Foreign antigens

Antigen-presenting cells (APCs) are cells of the immune system that are able to process and present foreign antigens to effector cells. The antigen is presented in the context of an MHC-I or MHC-II molecule on APCs in the presence of so-called costimulatory molecules to activate the effector cells. 

There is only one known type II IFN, IFN-y, discovered in 1965 (Wheelock and Sibley 1965). IFN-y is exclusively produced by immune cells, such as activated thymus-derived T cells and natural killer (NK) cells, after stimulation by foreign antigens or mitogens in the early stages of the innate immune response (Boehm etal. 1997). The human IFN-y gene maps to chromosome 12. IFN-y is a noncovalent... 

An APC is a cell that displays a foreign antigen complex with MHC on its cell surface. Its major responsibility is to present these foreign antigens to T cells. T cells can identify this complex using their T-cell receptors (TCRs). There are three main types of APCs dendritic cells, macrophages, and activated B cells. Dendritic cells (DCs) are present in tissues that... 

Allorecognition Recognition of the foreign antigens present on the transplanted organ or the donor s antigen-presenting cells. 

The T-lymphocyte receptor (TCR) is involved in detection of foreign antigens, presented together with the major histocompatibility complex (MHC). Subsequendy, it regulates the clonal expansion of T cells. 

Antibodies are specialized molecules produced by the immune system to attack foreign antigens. Therefore, an individual with type A blood produces... 

B lymphocytes, white blood cells originating in the bone marrow, are widely distributed throughout the body and are the essential elements of the immune system, which is responsible for synthesising antibodies against foreign antigens. 

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