HLA-DR/CD3

Human lymphocytes may be divided into three major populations based on their biologic function and cell-surface antigen expression: T lymphocytes, B lymphocytes, and natural killer (NK) lymphocytes. T lymphocytes participate in antigen-specific cell-mediated immunity and regulate the secretion of immunoglobulin by B lymphocytes. T lymphocytes may also be classified based on their functional properties as helper/inducer, suppressor/cytotoxic, or activated T lymphocytes.
Activated T lymphocytes (HLA-DR + T lymphocytes) may be elevated in states of immune activation, which may be caused by infection or impending transplant rejection. The actual cause of immune activation must be verified by additional clinical and laboratory tests.