Ultrastructure of lymphocytes in a case of pertussis syndrome.

A case of an 11-month-old black male with pertussis syndrome is described. He manifested a lymphocytic leukemoid reaction characterized by marked lymphocytosis and the presence of lymphoblasts in his circulation. A bone marrow examination did not reveal any evidence of acute leukemia. Electron microscopic examination of peripheral blood lymphoid cells revealed the presence of lymphoblasts and immature plasma cells, as well as unusual intramitochondrial and intranuclear bodies. The significance of these structures is discussed.