Jejunal mucosal enzyme activities, regulatory peptides and organelle pathology of the enteropathy of common variable immunodeficiency.

Jejunal biopsies from six patients having the small bowel enteropathy associated with common variable immunodeficiency have been subjected to analytical subcellular fractionation and enzymic and regulatory peptide microassay to define the organelle pathology of this syndrome. Compared with normal subjects, the immunodeficient patients had decreased activities of the three brush border enzymes: alkaline phosphatase, gamma-glutamyl transferase and alpha-glucosidase. The other organelle marker enzyme activities and all the regulatory peptide concentrations did not differ from the controls. Density gradient experiments showed a complete loss of particulate beta-glucosidase (lactase) with activity entirely located in the cytosol. The integrity of other organelles was normal. These data indicate that the enteropathy of common variable immunodeficiency is associated with abnormalities in the jejunal brush border analogous to those present in tropical malabsorption syndrome.