A plasma cell can be distinguished by its eccentric nucleus, numerous ovoid mitochondria, abundant rough endoplasmic reticulum and prominent Golgi apparatus. It is well adapted for efficient production and packaging of antibodies. A small population of lymphocytes, called null cells, do not express characteristics of either T cells or B cells. They do not possess normal levels of the same CD, TCR or mIg surface markers. The majority of these cells are large granular lymphocytes that are derived form pluripotent stem cells in the bone marrow.
Null cells appear quite heterogeneous with respect to surface markers expressed.
They are spontaneously cytotoxic to a variety of targets, including a certain cancer cells.