Apart from T & B lymphocytes, the other class of lymphocytes is -

Lymphoid cells The cells of the lymphoid system are lymphocytes. On the basis of function and surface markers, there are two major types of lymphocytes- T- cells B- cells When circulating lymphocytes are classified by their surface markers into T and B cells, about 5-10 percent of cells are found to lack features of either type they are called null cells/Large granular lymphocytes. Large granular lymphocytes include:            - Natural killer cells (N.K Cells)            - Antibody-dependent cytotoxic cells/killer cells (ADCC).            - Lymphokine-activated killer cells (LAK cells).