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. 2001 Feb;158(2):627–637. doi: 10.1016/S0002-9440(10)64004-7

Figure 5.

Figure 5.

Presence of immune complexes in baboon blood exposed to porcine lungs. Baboon blood that had been passed through porcine lungs, kidneys, or hearts (A and B) or that had been collected from recipients of pulmonary xenotransplants (C) was tested for the presence of porcine antigens by analysis of blocking of human xenoreactive antibodies. A: Blocking of human xenoreactive IgM by porcine antigen in baboon blood that had been passed through porcine lungs. Serum prepared from baboon blood before (pre) and after (post) perfusion through a porcine lung was diluted with PBS and treated with 10 mmol/L dl-dithiothreitol for 15 minutes at 37°C to depolymerize IgM and release bound antigen. The reduced serum was dialyzed against PBS in 10,000 MWCO cassettes to remove the dithiothreitol, and incubated with 5% human serum. The binding of human xenoreactive IgM to cultured porcine endothelial cells was tested by ELISA. Percent inhibition ±SE of triplicate determinations was based on the binding of 5% human serum IgM as a standard (standard errors are too small to be seen). The blocking of human xenoreactive antibodies indicated that the baboon blood contains porcine antigen that had been complexed with baboon antibodies. B: Porcine antigen in baboon blood perfused through various porcine organs. Porcine antigen was quantitated by measuring blocking of human xenoreactive IgM to porcine endothelial cells. Serum prepared from baboon blood before (pre) and after perfusion through a porcine lung, kidney, or heart was treated with dithiothreitol and dialyzed as described in A and incubated with 5% human serum. The binding of human xenoreactive IgM to cultured porcine endothelial cells was tested by ELISA. Percent inhibition ±SE of duplicate determinations was based on the binding of 5% human serum IgM as a standard. C: Blocking of human xenoreactive IgM by porcine antigen in the blood of baboons that received porcine pulmonary xenografts. Serum prepared from the blood of three baboons before (pre) and after (baboon 1, 2, and 3) pulmonary xenotransplantation was tested as described in A for the presence of porcine antigen. The “pre” result shown is the mean ±SE from the three baboons. Standard errors are too small to be seen. After pulmonary xenotransplantation, baboon blood contains antigen that is capable of blocking human xenoreactive natural antibodies.