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Ex‐vivo expanded baboon CD4 + CD25 Hi Treg cells suppress baboon anti‐pig T and B cell immune response
Author(s) -
Singh Avneesh K.,
Seavey Caleb N.,
Horvath Keith A.,
Mohiuddin Muhammad M.
Publication year - 2012
Publication title -
xenotransplantation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.052
H-Index - 61
eISSN - 1399-3089
pISSN - 0908-665X
DOI - 10.1111/j.1399-3089.2012.00697.x
Subject(s) - il 2 receptor , ex vivo , foxp3 , biology , immune system , baboon , cd28 , t cell , immunology , regulatory t cell , cytotoxic t cell , peripheral blood mononuclear cell , interleukin 21 , microbiology and biotechnology , in vivo , in vitro , endocrinology , biochemistry
Singh AK, Seavey CN, Horvath KA, Mohiuddin MM. Ex‐vivo expanded baboon CD4 + CD25 Hi Treg cells suppress baboon anti‐pig T and B cell immune response. Xenotransplantation 2012; 19: 102–111. © 2012 John Wiley & Sons A/S. Abstract: Background: CD4 + CD25 + FoxP3 + regulatory T (Treg) cells play an important role in regulating immune responses. A very small number of Treg cells are present in peripheral blood and lymphoid organs, but due to their ability to suppress the immune response, they have a high potential for immunotherapy in clinics. Successful ex‐vivo expansion of naturally occurring CD4 + CD25 + T cells has been achieved after TCR stimulation in the presence of T cell growth factors. In this study, we evaluated the role of these Treg cells in suppressing proliferative response of baboon T and B cells to pig xenoantigens. Methods: Naturally occurring baboon CD4 + CD25 + regulatory T cells (nTreg) were sorted from peripheral blood and expanded in the presence of either anti‐CD3/CD28 beads or irradiated pig peripheral blood mononuclear cells with IL‐2. Treg cells were also enriched directly from CD4 + T cells cultured in the presence of rapamycin (0.1–10 n m ). Mixed lymphocyte culture and polyclonal B cell stimulation with ex‐vivo Treg cells were performed to assess the function of ex‐vivo expanded Treg cells. Results: The nTreg cells were expanded to more than 200‐fold in 4 weeks and retained all the nTreg cell phenotypic characteristics, including high levels of FoxP3 expression. 2‐fold increase in enrichment of CD4 + CD25 + FoxP3 + Treg cells from CD4 + cells was observed with rapamycin compared to cultures without rapamycin. The ex‐vivo expanded Treg cells obtained from both methods were able to suppress the baboon anti‐porcine xenogeneic T and B cell immune response in‐vitro efficiently (more than 90% suppression at 1 : 1 ratio of T regulatory cells: T effector cells), and their suppression potential was retained even at 1 : 256 ratio. However, freshly isolated nTreg cells had only 70% suppression at 1 : 1 ratio, and their suppressive ability was reduced to ≤50% at 1 : 16 ratio. Furthermore, we have found that ex‐vivo expanded Treg can also suppress the proliferation of B cells after polyclonal stimulation. Forty to 50 percent reduction in B cell proliferation was observed when ex‐vivo expanded Treg cells were added to the culture at a 1 : 1 ratio. The addition of CD4 + CD25 Neg cells however induced vigorous proliferation. Conclusion: Ex‐vivo expanded CD4 + CD25 + FoxP3 + Treg cells can be used to efficiently suppress xenogeneic immune responses by inhibiting T and B cell proliferation. These ex‐vivo expanded Treg cells may also be used with other immunosuppressive agents to overcome xenograft rejection in preclinical xenotransplantation models.