Overview of lung transplantation

Lung Transplantation

The therapeutic options for patients with advanced pulmonary parenchymal or vascular disorders are currently limited. Lung transplantation remains one of the few viable interventions, but on account of the insufficient donor pool only a minority of these patients actually undergo the procedure each year. Following transplantation there are a number of early and late allograft complications such as primary graft dysfunction, allograft rejection, infection, post-transplant lymphoproliferative disorder and late injury that is now classified as chronic lung allograft dysfunction. The pathologist plays an essential role in the diagnosis and classification of these myriad complications. Although the transplant procedures are performed in selected centers patients typically return to their local centers. When complications arise it is often the responsibility of the local pathologist to evaluate specimens. Therefore familiarity with the pathology of lung transplantation is important.

Pharmacotherapy of Lung Transplantation

Lung transplantation has become a viable treatment therapy for end-stage lung disease patients. The most common etiologies of end-stage lung disease, which can require a transplant are chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), pulmonary arterial hypertension (PAH), and pulmonary fibrosis (PF). Listing criteria are institution and program specific. Approximately 1500 lung transplants were performed in 2008; and at 5 years post transplant, one-half are expected to survive. The surgery itself is associated with various complications, including surgical, infectious, and mechanical. Immunosuppression is paramount to the management of these patients, the goal being prevention of T cell activation to prevent rejection of the new organ. The patients commonly receive an induction agent with a T cell depleting antibody and high-dose corticosteroids. Maintenance immunosuppression begins immediately after the surgery, consisting of a combination of a calcineurin inhibitor, antimetabolite, and corticosteroids. Side effect profiles from the various agents will determine the choice of agents, and patients may have modifications throughout the therapy. The role of the pharmacist spans the inpatient management of acute complications to medication selection, management of maintenance immunosuppression, as well as monitoring for adverse drug reactions and drug–drug interactions. A multidisciplinary collaborative approach must be taken to ensure the best outcomes for this patient population.

Increased erythrocyte C4D is associated with known alloantibody and autoantibody markers of antibody-mediated rejection in human lung transplant recipients

BACKGROUND

Immune responses to mismatched donor human leukocyte antigens (HLA) are important in the pathogenesis of chronic rejection. This study evaluated whether erythrocyte-bound C4d (E-C4d) is associated with known alloimmune and autoimmune markers of antibody-mediated rejection after human lung transplantation (LTx).

METHODS

Flow cytometry was used to analyze 22 LTx recipients and 15 healthy individuals for E-C4d. Development of antibodies to donor-mismatched HLA (donor-specific antibody [DSA]) and antibodies to HLA were determined using the solid-phase method by Luminex. Development of antibodies to self-antigens, K-alpha-1-tubulin (KA1T) and collagen V (Col-V), were measured by enzyme-linked immunosorbent assay. C3d deposition in lung biopsy specimens was determined by immunohistochemical staining.

RESULTS

Percent E-C4d (%E-C4d) levels were 19.9% in LTx patients vs 3.7% in healthy individuals (p = 0.02). DSA+ patients had higher E-C4d levels than DSA- patients (34.1% vs 16.7%, p = 0.02). In 5 patients with preformed anti-HLA, E-C4d levels were not significantly different vs 13 patients without detectable anti-HLA (p = 0.1). E-C4d levels were higher in patients who developed antibodies to KA1T (p = 0.02) and Col-V (p = 0.03). Recipients with C3d-positive tissue deposition had higher E-C4d levels than patients with C3d-negative biopsy results (p = 0.01).

CONCLUSIONS

Increased %E-C4d levels are found in patients with positive DSA, high antibody titers to KA1T and Col-V, and have C3d+ lung biopsy findings. Therefore, %E-C4d can serve as a potential marker for antibody-mediated rejection after LTx.