The frequency of interleukin-10- and interleukin-5-secreting CD4 + T cells correlates to tolerance of transplanted lung

Posttransplant bronchiolitis obliterans syndrome (BOS) results from a chronic immunological/inflammatory insult that leads to fibro-obliteration of the lumen of the allograft airways. The functional T-cell response that is associated with graft acceptance needs to be further clarified in humans. The aim of the present study was to assess the functional activity of peripheral CD4⁺ T lymphocytes in nine lung transplant recipients with BOS stage II or III (mean 5.4 years after transplant), in seven lung patients with stable clinical conditions (3.4 years posttransplant); and in six normal controls. Peripheral CD4⁺ T cells, obtained by magnetic bead vs negative purification, were studied using a computer-assisted enzyme-linked immunospot assay (ELISPOT) to assess the number of IFN-γ-, interleukin (IL)5-, and IL10-γ-producing cells (no./10⁶ CD4⁺ cells) after allogeneic stimulation. The frequencies of IFN-γ-producing CD4⁺ cells did not change significantly in stable patients compared to those with BOS. Interestingly in BOS, the number of IL5- and IL10-producing cells was significantly lower than in stable patients (P ≤ .05), suggesting a possible role of these Th2 cytokines in the modulation of graft tolerance.