Exaggerated humoral response develops in TLT.

<p><b>A.</b> The number of CD3+ cells (black line) and the proportions of CD4+ and CD8+ subsets (histogram) infiltrating the adventitia of rat aortic allografts were measured 10 days, 1 month and 2 months post-transplantation. The low number of cells at 2 months precluded the analysis of T lymphocyte phenotype at this time point. <b>B.</b> The distribution of CD4+ and CD8+ subpopulations among CD3+ cells was similar in the three lymphoid organs one month post-transplantation. <b>C.</b> Transversal sections of aortic allografts were stained with an anti-B lymphocyte monoclonal antibody. The scattered pattern of infiltration observed in the adventitia at 10 days <b>(left panel)</b> was replaced by an organized tertiary lymphoid tissue at 1 month <b>(right panel)</b>. <b>D.</b> The amount and the specificity of the antibodies present in the supernatants from tissue cultures of adventitia of chronically rejected aortic allograft, draining lymph nodes, and spleen was analyzed by flow cytometry using a Lewis (recipient) fibroblast cell line (LEW-F; negative control) and the same cell line transfected with the RT1.A1ⁿ (LEW-F+A1ⁿ) or the RT1.A2ⁿ (LEW-F+A2ⁿ) donor MHC I molecules. Cells were incubated with 100 µl of each supernatant. The binding of antibodies on the cell surface was determined with a FITC-conjugated anti-rat Ig κ light chain antibody by measuring the mean fluorescence intensity in a flow cytometer. Cell suspensions from the spleen, the draining lymph nodes and the adventitia of chronically rejected aortic graft were obtained from 10 recipient rats 1 month post-transplantation and analyzed by flow cytometry. Adventitia <i>vs</i> spleen: ‡‡‡ p<0.001; adventitia <i>vs</i> draining lymph node: *** p<0.001.