Impaired bacterial degradation by monocytes and macrophages from a patient with treated Whipple's disease.

A patient with Whipple's disease is described, and multiparameter flow cytometric examinations of several of the patient's phagocyte functions 3 and 9 mo after the start of oxytetracycline therapy are reported. Almost no intracellular degradation of Escherichia coli or Streptococcus pyogenes proteins and DNA occurred after ingestion by the patient's monocytes and macrophages. In addition, only minor digestion of phagocytized zymosan particles was detected. The mononuclear intracellular degradation was equally impaired 3 and 9 mo after the start of therapy. The monocyte and macrophage phagocytosis and intracellular killing, and all granulocyte phagocyte functions tested, were normal. The impaired mononuclear degradation of ingested material that was measured is consistent with the accumulation of periodic acid-Schiff-positive bacterial degradation products seen in macrophages of affected tissues in vivo, and suggests a key role of macrophage dysfunction in the pathogenesis of Whipple's disease.