Early chimerism of macrophages and lymphocytes in lung transplant recipients is predictive of graft tolerance

Long-Term Persistence of Donor Alveolar Macrophages in Human Lung Transplant Recipients That Influences Donor-Specific Immune Responses

Steady-state alveolar macrophages (AMs) are long-lived lung-resident macrophages with sentinel function. Evidence suggests that AM precursors originate during embryogenesis and populate lungs without replenishment by circulating leukocytes. However, their presence and persistence are unclear following human lung transplantation (LTx). Our goal was to examine donor AM longevity and evaluate whether AMs of recipient origin seed the transplanted lungs. Origin of AMs was accessed using donor-recipient HLA mismatches. We demonstrate that 94-100% of AMs present in bronchoalveolar lavage (BAL) were donor derived and, importantly, AMs of recipient origin were not detected. Further, analysis of BAL cells up to 3.5 years post-LTx revealed that the majority of AMs (>87%) was donor derived. Elicitation of de novo donor-specific antibody (DSA) is a major post-LTx complication and a risk factor for development of chronic rejection. The donor AMs responded to anti-HLA framework antibody (Ab) with secretion of inflammatory cytokines. Further, in an experimental murine model, we demonstrate that adoptive transfer of allogeneic AMs stimulated humoral and cellular immune responses to alloantigen and lung-associated self-antigens and led to bronchiolar obstruction. Therefore, donor-derived AMs play an essential role in the DSA-induced inflammatory cascade leading to obliterative airway disease of the transplanted lungs.

Eight years of lung transplantation: experience of the National Research Institute of Tuberculosis and Lung Diseases

BACKGROUND

Lung transplantation has evolved from an experimental procedure to a viable therapeutic option in many countries. In Iran, the first single-lung transplantation was performed in the year 2000, more than 3 decades after the first successful procedure in the world, and the first double-lung transplantation was performed in the year 2006.

OBJECTIVE

To describe our 8-year experience in lung transplantation.

PATIENTS AND METHODS

During 8 years, we performed 24 lung transplantation procedures. Underlying lung diseases were pulmonary fibrosis in 16 patients (66.6%); chronic obstructive pulmonary disease in 2 (8.3%); bronchiectasis in 5, including 2 patients with cystic fibrosis (20.8%), and alveolar microlithiasis in 1 (4.16%). Data for all patients were collected and analyzed. Procedures were carried out using standardized methods. The induction suppression regimen consisted of cyclosporine and methylprednisolone. Maintenance immunosuppression drugs were cyclosporine and mycophenolate mofetil, and tapering dosage of prednisolone. Patients were followed up with physical examinations, 3 times a week, as well as and cycle ergometry 3 times a week and spirometry and laboratory tests once a week and chest radiography per needed for up to 3 months posttransplantation.

RESULTS

The longest survival time was 7.2 years, in a 60-year-old patient with idiopathic pulmonary fibrosis. Fourteen patients died, 8 as a result of hemodynamic instability and/or hemorrhage, 1 as a result of bone and fat emboli, 3 after cessation of drug and 2 of them after infection.

CONCLUSION

Although lung transplantation is a complex procedure it can be performed in developing countries such as Iran.

Upregulation of CD40, CD80, CD83 or CD86 on alveolar macrophages after lung transplantation

BACKGROUND

Alveolar macrophages (AMs) are known to be poor antigen-presenting cells, and lack the accessory molecules such as CD40, CD80 or CD86 to activate T cells. The question raised is about the potential changes in phenotypes after lung transplantation, particularly during acute rejection episodes.

METHODS

The present study analyzed the phenotype of AMs longitudinally in 45 lung transplant patients, between August 1997 and April 2002, with a follow-up period of 27.2 +/- 2.5 (mean +/- SEM) months. There were 7.7 +/- 0.6 bronchoalveolar lavage (BAL) assessments performed per patient (i.e., 345 BALs), simultaneously with transbronchial biopsies. Transplantation was soon followed by a progressive upregulation of CD40 on 49.7 +/- 8% of AMs during the first month, and this marker remained elevated at 60 +/- 8% after 5 years.

RESULTS

Both CD86 and CD80, as well as CD83, a marker of dendritic cells, were enhanced for most AMs during Grade A2 and A3 rejection episodes. A correlation was found between expression of CD83 and CD86, but not between CD1a and CD86. Immunohistology confirmed that CD40-positive cells in the alveoli corresponded to AMs and to some dendritic cells in the basal layers of the airways. In vitro studies showed that harvested AMs with these enhanced accessory molecules remained poor stimulators of allogeneic cells, a phenomenon that may be related to the ongoing immunosuppressive treatments.

CONCLUSIONS

AM phenotypes showed marked changes during early or late acute rejection episodes, acquiring CD80, CD83 and CD86, while CD40 expression was further enhanced. This finding may provide clues on how to monitor the tolerance of transplanted lungs and may also provide new insights into the pathophysiology of lung transplantation.