Case 41

Published on 18/02/2015 by admin

Filed under Allergy and Immunology

Last modified 18/02/2015

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CASE 41

Geoffrey is a 14-month-old child born with biliary atresia (absence of the biliary tree). His parents are advised that the only possibility of cure and a normal life is a liver transplant. Given the shortage of donors, the surgeon discusses the risk/benefit of living related transplants. Both parents are eager to consent, although the best match is deemed to be the father. Surgery involves transplantation of the left lobe of the father’s liver to his son. Both surgeries go well, and both patients make excellent recoveries, returning home within a week after surgery. There are no further complications of the father’s care. Some 4 weeks after the transplant, Geoffrey develops a desquamating, erythematous rash over his trunk, legs, and arms, a low-grade fever, and some diarrhea. His parents return him to the transplant center and are very concerned.

There has been no dramatic change in Geoffrey’s post-transplant immunosuppressive regimen. Blood work looks relatively normal, with some moderate elevation of liver function tests. The diarrhea is quite profuse, although stool cultures are negative for infectious organisms. In fact, blood cultures, urine, induced sputum, and even a lumbar puncture fail to identify an infectious cause of disease, despite evidence for a continuing low-grade fever. During the third hospitalization day he actually becomes quite tachypneic (short of breath), although again a chest radiograph fails to document any obvious pathologic process. He is holding reasonable oxygen saturation only when receiving high-flow 100% oxygen. Of particular concern, you have not been able to discern the cause of the rash, and he is only maintaining normal urine output with vigorous fluid resuscitation. The nurse in the intensive care unit comments that only in burn patients has she seen a rash this bad.

QUESTIONS FOR GROUP DISCUSSION

1. Acute and chronic rejection of a graft by a host is referred to as host-versus-graft disease (HvGD). Compare these two types of HvGD with respect to effector cells, time of onset, and treatment (see Case 42).

2. Explain why immunosuppressive therapy is essential for all transplants except for those from an identical twin.

3. Patients on immunosuppressive therapy have risk factors that are unrelated to the graft itself. Discuss these factors.

4. None of the risk factors (see question 3) will present as a desquamating rash (shedding of the outer layer of skin/epidermis). Furthermore, this complication occurs only with intestinal, bone marrow, and liver transplants. What do these tissues have in common?

5. Graft versus host disease (GvHD), as the term implies, refers to the immunologic assault of the host tissues by the graft. Given that one of the prominent features of GvHD is the desquamating rash, to what host antigens is this immunologic response directed?

6. Immunologic responses in HvGD and GvHD involve the same components of the immune system. In HvGD the host is targeting the graft, whereas in GvHD the graft is targeting the host tissues. In both these scenarios, CD4+ Th1 cells play a significant role. Review immunologic responses that require Th1-derived cytokines. (Begin by listing the type 1 cytokines.)

7. With reference to question 6, how would you treat GvHD?

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