Immunoglobulin A and secretory immunoglobulin A in the bronchoalveolar lavage from patients after lung transplantation

Secretory immunoglobulin A (sIgA) is the most important Ig on mucosal surfa ces. In bronchoalveolar lavage (BAL) fluid, sIgA is mainly produced by broo ch us-associated lymphoid tissue (BA LT). The presence of pre-formed antibo dies against donor tissue in kidney transplantation is associated with hype racute rejection, indicating a humoral (antibody-mediated) reaction. In hea rt and liver transplantation, humoral rejection has also been documented. T he goal of this study was to evaluate the role of IgA in patients after lun g transplantation. An enzyme-linked immunosorbent assay was established to determine the levels of sIgA, IgA, and total protein in the lavage. IgA and sIgA were both detectable in BAL from transplanted lungs. IEA and sIgA lev els were both higher during episodes of infection than during episodes of r ejection or during the control episodes. The level of IgA during episodes o f rejection equaled the level of IEA during the control episodes. The level of sIgA was significantly decreased during episodes of acute rejection (1. 8 +/- 1.0 mug/mL) when compared with the control (7.2 +/- 1.0 mug/mL; p = 0 .013). This study demonstrates that BALT retains the ability to produce Ig even after lung transplantation. The levels of IgA and sIgA and their ratio do not contribute to the differentiation between rejection and infection i n lung-transplanted patients.