Immunology

Neonatal Porcine Sertoli Cells Inhibit Human Natural Antibody-Mediated Lysis

Abstract
Sertoli cells protect co-transplanted cells from allogeneic and xenogeneic rejection. Additionally, neonatal porcine Sertoli cells (NPSCs) survive long-term as xenografts in non-immunosuppressed rodents. This has led to the hypothesis that NPSCs could be used to prevent cellular rejection in clinical transplantation, thereby eliminating the need for chronic immunosuppression. Prior to transplantation of NPSCs in humans it is necessary to determine if they are also protected from humoral-mediated xenograft rejection. The presence of Gal(1,3)Gal(1,4)GlcNAc-R (Gal epitope) as well as binding of human IgG and IgM to NPSCs was examined by immunocytochemical and FACS analysis. Gal was detected on 88.5 ± 3.0 % of NPSCs. Consistent with this, 71.7 ± 1.0 and 65.4 ± 5.2 % of NPSCs were bound by IgG and IgM, respectively. When cultured NPSCs underwent an in vitro cytotoxicity assay by incubation with human AB serum plus complement, no increase in cellular lysis was observed, while controls, porcine aorta endothelial cells, were shown to contain >60% dead cells. Finally, activation of the complement cascade was examined by immunohistochemistry. C3 and C4 were deposited on the surface of the NPSC membrane indicating activation of complement. Although the complement cascade was activated, the membrane attack complex (MAC) was not formed. These data demonstrate that, despite expression of Gal, binding of xenoreactive antibodies, and the activation of complement, NPSCs survive human antibody/ and complement-mediated lysis by preventing MAC formation. This suggests NPSCs may be able to survive humoral-mediated rejection in a clinical situation.

Key words: Immunology • Male Reproductive Tract • Testis • Sertoli cells