Antibody- and complement-independent phagocytotic and cytolytic activities of human macrophages toward porcine cells.
BACKGROUND
It has been speculated that host macrophages contribute to rapid clearance of transplanted xenogeneic cells. To address such a possibility, phagocytotic and cytolytic activities of human macrophages toward xenogeneic porcine cells were evaluated in vitro in the absence of antibodies and complement factors.


METHODS
Human peripheral monocyte-derived macrophages (P-macrophages) and reticulo-endothelial macrophages (RE-macrophages) were obtained from volunteers' peripheral blood and from the perfusion effluents of liver allografts for transplantation, respectively. 5-(and 6-) carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled human autologous red blood cells (auto-RBCs), ABO-incompatible RBCs (incom-RBCs) and xenogeneic porcine RBCs (xeno-RBCs) were incubated with the human macrophages; subsequently, the macrophages that had phagocytosed the RBCs could be identified as CFSE positive cells by FCM analyses and confocal microscopy. Cytolytic activity was quantified by calculating levels of lactate dehydrogenase in each culture supernatant.


RESULTS
Human RE-macrophages spontaneously phagocytosed and had a remarkable cytolytic activity toward xeno-RBCs, but not toward auto-RBCs or incom-RBCs. Elimination of alpha-galactosyl xenoantigen (alpha-Gal) epitopes on xeno-RBCs did not prevent phagocytotic or cytolytic activity of RE-macrophages.


CONCLUSIONS
These findings indicate phagocytotic and cytolitic activities of human macrophages toward porcine cells are initiated by a factor other than alpha-Gal in a mechanism independent of antibody/complement opsonization.
Ide
Kentaro
K
Department of Surgery, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Science, Hiroshima University, Japan.
Ohdan
Hideki
H
Kobayashi
Takaaki
T
Hara
Hidetaka
H
Ishiyama
Kohei
K
Asahara
Toshimasa
T
D000818:Animals; D000906:Antibodies / Q000502:physiology; D015478:Antigens, Heterophile / Q000502:physiology; D003165:Complement System Proteins / Q000502:physiology; D000939:Epitopes / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000502:physiology*; D009000:Monocytes / Q000166:cytology; D012157:Mononuclear Phagocyte System / Q000166:cytology; D009895:Opsonin Proteins / Q000502:physiology; D010587:Phagocytosis / Q000502:physiology*; D013552:Swine / Q000097:blood*; D014312:Trisaccharides / Q000502:physiology
D000906:Antibodies; D015478:Antigens, Heterophile; D000939:Epitopes; D009895:Opsonin Proteins; D014312:Trisaccharides; C076569:alpha-galactosyl epitope; D003165:Complement System Proteins; D007770:L-Lactate Dehydrogenase