Tacrolimus (fk506) Induced Colitis in Pediatric Liver Transplant (Olt) Recipients. Is It Allergic in Nature?

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FK506 is a macrolide immunosuppressive that is increasingly being used for prevention of graft rejection in transplant recipients. It shares similar toxicity profiles with cyclosporine (CSA). However, very little is reported about its GI side effects. We retrospectively identified 3 patients who were started on FK506 post OLT and developed biopsy proven colitis, thought to be allergic in nature. Case 1 underwent OLT after a failed Kasai procedure for biliary atresia; 20 mos later, he developed guaiac positive diarrhea, neg for pathogens. Colonoscopy revealed focal colitis. He was also noted to have peripheral eosinophilia (24%) and positive RAST for milk protein. CSA was substituted for FK506 with resolution of symptoms on a milk restricted diet. Case 2 received OLT for Alagille syndrome at 33 mos of age (CSA primary therapy). FK506 was started a month later for mild rejection. He developed diarrhea 23 mos later, negative for pathogens. Flexible sigmoidoscopy revealed active as well as chronic inflammation. He had mild eosinophilia but normal IgE levels. A month later he developed PTLD along with marked eosinophilia (32%) and was switched to CSA as well as a milk restricted diet with resolution of symptoms. Case 3 underwent OLT for fulminant hepatic failure of unknown etiology, followed 4 mos later by BMT for aplastic anemia. 17 mos after OLT, he developed guaiac positive diarrhea, negative for pathogens. Peripheral eosinophilia (∼9%) was also found. Colonoscopy revealed increased mucosal eosinophils without activity or evidence of GVHD. RASTs were positive for milk, wheat, eggs, and oats. He was placed on a restricted diet but persistence of symptoms necessitated switch to CSA with subsequent resolution of symptoms.


In these patients, FK506 was associated with the induction of allergic colitis. Therapy was facilitated by discontinuation of FK506 and switch to CSA. More studies are needed in a controlled setting to identify the prevalence of similar findings among pediatric liver transplant recipients.

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