Detection of HIV‐1 Protein and Nucleic Acid in Enterochromaffin Cells of HIV‐1‐Seropositive Patients

Diarrhea contributes significantly to the morbidity and mortality of patients with the acquired immunodeficiency syndrome (AIDS). Up to 50% of AIDS patients have diarrhea, and an etiologic agent for this cannot be identified in all of them. Recent evidence suggests that enterochromaffin cells may be infected by the human immunodeficiency virus type 1 (HIV‐1) and may contribute to the unexplained diarrhea. To test this hypothesis further, endoscopic biopsies of duodena from 22 HIV‐1 seropositive patients [17 with diarrhea (>500 g/day and >3 bowel movements/day), five without diarrhea] and from 15 normal controls (no HIV risk factors) without diarrhea were studied. Formalin‐fixed and paraffin‐embedded 5‐μm sections were examined by immunocytochemistry, using a monoclonal antibody to the HIV‐I gp41 protein, and by in situ hybridization with a full‐length biotinylated HIV‐1 DNA probe. Positive staining for gp41 was detected in crypt cells, consistent with the location, size, and morphology of enterochromaffin cells, in 11 of 17 HIV‐1‐seropositive patients with diarrhea, and in none of five without diarrhea. Nucleic acid hybridization staining was performed in five of the 11 patients who had positive gp41 staining; all showed HIV nucleic acid sequences in similar cells. All three of the five patients with positive staining for HIV nucleic acid sequences bad diarrhea for which no etiologic agent for diarrhea could be found, and one each had cryptosporidia or microsporidia. No staining was observed in any of the samples from normal control tissues. These results suggest that HIV‐1 may infect enterochromaffin cells and possibly alter their function. This, in turn, may contribute to the diarrhea associated with AIDS.