Immunocytochemistry in the diagnosis of Whipple's disease.

In six cases of Whipple's disease the characteristic macrophages could be stained immunocytochemically using a first layer antiserum to group B streptococci. Other types of periodic acid Schiff positive macrophages were negative. The staining appears to be due to a rhamnose containing polysaccharide as shown by a blocking test. The method may be useful for confirming the diagnosis in rectal biopsy and peripheral nodes, especially if small intestinal findings are atypical.