n :  a T cell that participates in an immune response by recognizing a foreign antigen and secreting lymphokines to activate T cell and B cell proliferation, that usu. carries CD4 molecular markers on its cell surface, and that is reduced to 20 percent or less of normal numbers in AIDS - called also helper cell , helper lymphocyte , helper T lymphocyte  - compare KILLER T CELL SUPPRESSOR T CELL  .
 
 
 
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