What are antigens, and how do lymphocytes “recognize” them?

Question

blurbendy · Answer

Lymphocyte antigen receptors, in the form of immunoglobulins on B cells and T-cell receptors on T cells, are the means by which lymphocytes sense the presence of antigens in their environment. source: http://www.ncbi.nlm.nih.gov/books/NBK10774/

shiraz14 · Answer

Antigens are often proteins expressed on a cell's surface membrane although some of these may be flagged by separate antigen presenting cells to lymphocytes & thymocytes in the vicinity. Lymphocytes recognize these antigens as they have specific receptors which bind to the heavy chain region of antibodies produced by the lymphocytes. It is VDJ recombination which allows for the production of a large variety of antibodies which are able to recognize and bind to different antigens.