Expression of complement regulatory proteins on human eggs and preimplantation embryos.
OBJECTIVE
To investigate the relation between the complement system and reproduction, expression of complement regulatory proteins (C3b receptors and inhibitor of the membrane attack complex) were screened on unfixed human eggs and preimplantation embryos.


METHODS
Unfixed unfertilized oocytes and preimplantation embryos obtained from an in vitro fertilization program were stained by indirect immunofluorescence using monoclonal antibodies raised against membrane cofactor protein, (MCP or CD46), decay accelerating factor (DAF or CD55), protectin (CD59), human C3b/C4b receptor (CR1 or CD35), and major histocompatibility complex class I antigen (MHC class I).


RESULTS
CD55 and CD59 were both expressed by the plasma membrane of unfertilized oocytes and pre-implantation embryos. CD46 was not expressed by unfertilized oocytes but appeared at the 6-to-8 cell stage embryo when human gene expression first occurs. CD35 and MHC class I antigens were not expressed at all on oocytes and preimplantation embryos.


CONCLUSIONS
Selective expression of complement regulatory proteins (DAF and protectin) associated with the lack of MHC class I antigens may represent an immune protective mechanism by which human oocytes and preimplantation embryos escape complement-mediated damage during their travel through the female genital tract. Furthermore, participation of these complement regulatory proteins including MCP in cell to cell interaction during fertilization and/or implantation cannot be excluded.
Fenichel
P
P
INSERM U364, Faculté de Médecine, Nice, France.
Donzeau
M
M
Cervoni
F
F
Menezo
Y
Y
Hsi
B L
BL
D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D001755:Blastocyst / Q000737:chemistry / Q000378:metabolism*; D018958:CD55 Antigens; D018957:CD59 Antigens; D003169:Complement Inactivator Proteins / Q000096:biosynthesis* / Q000276:immunology; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006680:HLA Antigens / Q000096:biosynthesis / Q000276:immunology; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000276:immunology; D006801:Humans; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism*; D017463:Receptors, Complement 3b / Q000096:biosynthesis / Q000276:immunology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C497857:CD46 protein, human; D018958:CD55 Antigens; D018957:CD59 Antigens; D003169:Complement Inactivator Proteins; D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D017463:Receptors, Complement 3b