Absence of natural killer cells in a child with pure red blood cell aplasia

A 16-year old boy was known to suffer from red blood cell (RBC) aplasia from the age of 4 years. Peripheral blood lymphocytes (PBL) from the patient were found to lack natural killer (NK) cytotoxic activity, even after stimulation with alpha-interferon. His PBL also lacked Leu-7+ and Leu-11+ cells, although his granulocytes showed normal expression of the Leu-11 marker. The lack of NK cells did not seem to result from the various immunosuppressive treatments he received, since the NK deficiency was noted 2 years after he stopped receiving such treatment. The possibility is discussed that lack of NK cells may lead to the development of RBS aplasia if NK cells play a role in promoting the production of RBC.