Circumscribed intestinal protein loss with deficiency in CD4+ lymphocytes after the Fontan procedure

Abstract

Protein-losing enteropathy is an important complication after right heart bypass operations (Fontan procedure). Laboratory examinations usually reveal hypoalbuminaemia, hypoproteinaemia, elevated α₁-antitrypsin clearance, and lymphocytopenia. A case of protein-losing enteropathy after Fontan procedure is reported with a circumscribed protein loss in the region of the terminal ileum despite good haemodynamics. The patient developed only mild hypoalbuminaemia and no diarrhoea but severe cellular and humoral immune abnormalities, namely a markedly decreased proportion of CD4+ lymphocytes but normal proportion of CD8+ lymphocytes (CD4+ 14%, CD8+ 23%) and decreased serum levels of immunoglobulin G. Intestinal biopsies revealed normal mucosa. This report is unique as it is the first to describe a ratio of CD4+ to CD8+ lymphocytes <1 due to an almost selective loss of CD4+ lymphocytes and a circumscribed intestinal protein loss in a patient who developed protein-losing enteropathy after Fontan operation.

Conclusion There is a severe decrease of CD4+ lymphocytes of unknown origin in a patient with circumscribed intestinal protein loss after Fontan operation. Passive leakage of lymph fluid due to abnormal systemic venous pressure is not a sufficient explanation of the almost selective loss of CD4+ lymphocytes. Primary or secondary activation of the immune system may influence structural integrity and permeability of the intestinal wall and may play a triggering role in protein-losing enteropathy after the Fontan procedure.