Immunological studies of lactoferrin in human placentae.
Lactoferrin (LF) and transferrin (Trf) are glycoproteins with strong affinities for ferric ions. Human syncytiotrophoblastic membranes analyzed by enzyme linked immunosorbent assay (ELISA) and immunoblotting were negative with monoclonal and polyclonal antibodies to LF. Immunohistological studies of 35 normal placentae showed that LF was absent from the trophoblast basement membranes, stroma and fetal stem vessel endothelium, but positive cells were occasionally noted in intervillous spaces and fetal stem vessels. In contrast, many LF-positive cells were identified within areas of immunopathology identified by the presence of T cells, HLA-DR-positive macrophages and platelets. Double-antibody experiments showed that the LF-positive cells in these areas reacted with CD15 and CD16 monoclonal antibodies (mAbs), indicating that the cells were polymorphonuclear neutrophils (PMN). PMN from peripheral blood analyzed by flow cytometry and immunocytology also showed reactivities with anti-LF, CD15 and CD16 and we consistently found that circulating PMN reacted better than placental PMN with antibodies to MHC class I antigens and gp 100, (CD67), which is a neutrophil activation marker. PMN adherent within placentae had no detectable MHC class I or CD67 antigens. These findings suggest PMN adherent to placental tissues down-regulate or alter plasma membrane markers. LF appears to play a role in placental inflammation, for LF-positive cells were significantly enriched in areas of immunopathology.
Thaler
C J
CJ
Center for Reproduction and Transplantation Immunology, Methodist Hospital of Indiana, Indianapolis 46202.
Labarrere
C A
CA
Hunt
J S
JS
McIntyre
J A
JA
Faulk
W P
WP
D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000096:biosynthesis; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004727:Endothelium / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D007781:Lactoferrin / Q000096:biosynthesis* / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D016256:Lewis X Antigen; D010920:Placenta / Q000378:metabolism*; D017452:Receptors, IgG / Q000096:biosynthesis; D017154:Stromal Cells / Q000276:immunology; D014327:Trophoblasts / Q000276:immunology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D016256:Lewis X Antigen; D017452:Receptors, IgG; D007781:Lactoferrin