Human mucosal-associated invariant T (MAIT) cells express the semi-invariant T cell receptor Vα7.2 and are restricted by the MHC-Ib molecule MR1. While MAIT cells share similarities with other innate T cells the extent to which MAIT cells are innate and their capacity to adapt is unknown. We evaluated the function of Vα7.2 + T cells from the thymus, cord blood, and peripheral blood. While antigen-inexperienced MAIT cells displayed a naive phenotype these had intrinsic effector capacity in response to Mycobacterium tuberculosis infected cells. Vα7.2 + effector thymocytes contained sjTREC suggesting limited replication and thymic origin. In evaluating the capacity of Mtb-reactive MAIT cells to adapt, we found that those from peripheral blood demonstrated a memory phenotype and had undergone substantial expansion suggesting they responded to antigenic stimulation. MAIT cells, an evolutionarily conserved T cell subset that detects a variety of intracellular infections, share features of innate and adaptive immunity.

Anatomic repair of congenitally corrected transposition of the great arteries can be carried out with low early mortality. Excellent functional status can be achieved, with good midterm survival. Continued surveillance is necessary for patents with valved conduits and to determine the longer-term function of the aortic valve and the morphologically left ventricle in the systemic circulation.

Background-Some patients with a morphological right ventricle (mRV) in the systemic circulation require early intervention because of progressive systemic ventricular dysfunction or atrioventricular valve regurgitation. They may be eligible for anatomic repair (correction of atrioventricular and ventriculoarterial discordance) but require prior training of the morphological left ventricle (mLV). Methods and Results-Forty-one patients with congenitally corrected transposition of the great arteries or a previous atrial switch procedure embarked on a protocol of pulmonary artery (PA) banding with a view to anatomic repair. All had an mRV in the systemic circulation and a subpulmonary mLV that was not conditioned by either volume or pressure load. Two patients were not banded, and 39 were followed up for a median of 4.3 years (range, 25 days to 12.6 years). Sixteen patients achieved anatomic repair, with 3 in the early stages of the training protocol. After 2 years, 12 patients were not suitable for anatomic repair and persisted with palliative banding; 8 were functionally improved; and 4 died, underwent transplantation, or required debanding. PA banding improved functional class but did not improve tricuspid regurgitation in the long term for patients not achieving anatomic repair. mLV function was a critical determinant of survival with a PA band as well as survival after anatomic repair. Patients Ͼ16 years were unlikely to achieve anatomic repair. Conclusion-PA banding is a safe and effective method of training the mLV before anatomic repair. It is also an effective palliative procedure for those who do not attain this goal.

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In this contemporary series, the modified Fontan procedure was characterised by low early mortality, excellent midterm survival, and improved functional class independent of the morphology of the single functional ventricle. Nevertheless, a morphologic right ventricle was a risk factor for prolonged in-patient hospitalisation and may yet influence long term survival.