Autoimmune panleukopenia.

A patient with episodic panleukopenia involving neutrophilic granulocytes, monocytes and lymphocytes had recurrent bacterial infections and a circulating cytotoxin that injured primitive myeloid cells as well as differentiated granulocytes and mononuclear cells. The cytotoxin was an immunoglobulin with activity against mouse, as well as human, myeloid stem cells. Clinical remission during cyclophosphamide therapy was associated with disappearance of the circulating leukocytotoxin. Serum from a period of active disease was cytotoxic for the patient's own lymphocytes obtained during clinical remission. Absorption of cytotoxic serum with granulocytes removed activity against both granulocytes and lymphocytes. These studies suggest an autoimmune disease in man characterized by episodic granulocytopenia, monocytopenia and lymphocytopenia due to humoral antibody against non-HLA antigens shared by several hematopoietic cell lines.