Scanning electron microscopy of soy protein-induced damage of small bowel mucosa in infants

Observations are reported by scanning electron microscopy (SEM) of soy protein-induced villous atrophy and mucosal recovery in two infants aged 5 weeks and 4 1/2 months. Whereas, by light microscopy, the mucosal lesions appeared similar, i.e., a flat mucosa, their appearance by SEM was different: the damage appeared more severe in the younger infant, although there was a shorter period of exposure to soy protein. The mucosal architecture was restudied 6 weeks after the initial biopsy. The degree of mucosal reconstruction was more advanced in the older infant--the one who showed less severe damage by SEM on the first biopsy. Although these investigations by SEM of damaged small bowel mucosa in soy protein intolerance did not contribute definite information to clarify the pathogenesis of villous atrophy in this condition, the injury was consistent with a lectin-induced toxicity, similar to the one postulated for celiac disease. SEM seems eminently suited to study of the effect of interactions between environment and host at mucosal surfaces; and finer gradations of damage to small bowel mucosa can be determined better by SEM, while this is not possible by light microscopy. Of interest was the rather extensive colonization of the mucosal surface by microorganisms in one of the two patients. However, the contribution of microbial colonization to mucosal damage could not be assessed.