lymphocyte /lim″fəsīt/ [L, lympha + Gk, kytos, cell] , a family of mononuclear, nonphagocytic white blood cells that circulate in blood, lymph, and peripheral lymphatic tissues. Lymphocytes are categorized as B and T lymphocytes and natural killer cells and are responsible for humoral and cellular immunity and tumor surveillance. Also called lymph cell. See also lymphokine. −lymphocytic, adj.
