Biochemical and functional characterization of xenoreactive natural antibodies in hu-PBL-SCID mice.
An in vivo model system to understand the mechanism of xenograft rejection was established using human peripheral blood leukocyte-reconstituted SCID (hu-PBL-SCID) mice. Human xenoreactive natural antibodies (XNA), of IgM and IgG subtypes, capable of binding to pig aortic endothelial cells (PAEC) were detected in the sera of hu-PBL-SCID by ELISA and flowcytometric methods. Western blot analysis of PAEC lysates showed that IgM and IgG XNA from hu-PBL-SCID recognized xenoantigens with similar molecular mass as those recognized by XNA from normal human serum (NHS). This result demonstrated that hu-PBL-SCID contained XNA representing the same repertoire as that of the NHS. XNA from NHS and hu-PBL-SCID were also able to induce intracellular Ca2+ signals in cultured PAEC several fold above the basal level. This result revealed their functional similarity and demonstrated for the first time that XNA in the absence of C can activate PAEC, which may lead to the pathology of xenograft rejection. In vivo, PAEC transplanted under the kidney capsule of hu-PBL-SCID mice showed deposition of human IgM and mouse C. In summary, the present study demonstrates that hu-PBL-SCID can serve as a useful model to characterize innate immunity against xenograft.
Naziruddin
B
B
Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Shiroki
R
R
Shishido
S
S
Howard
T
T
Mohanakumar
T
T
D000818:Animals; D000910:Antibodies, Heterophile / Q000097:blood / Q000502:physiology*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006084:Graft Rejection; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*
D000910:Antibodies, Heterophile; D002118:Calcium