Ek. Kristoffersen et R. Matre, COLOCALIZATION OF BETA-2-MICROGLOBULIN AND IGG IN HUMAN PLACENTAL SYNCYTIOTROPHOBLASTS, European Journal of Immunology, 26(2), 1996, pp. 505-507
The fetal syncytiotrophoblast cells in close contact with maternal blo
od circulation apparently lack surface expression of HLA molecules, in
cluding the HLA light chain beta 2-microglobulin. This is thought to c
ontribute significantly to a successful pregnancy. We find that syncyt
iotrophoblasts do express beta 2-microglobulin. beta 2-microglobulin i
s primarily localized intracellularly in apical granules, and co-local
ize with human IgG. The origin and function of syncytiotrophoblast bet
a 2-microglobulin is unknown, but its localization in the syncytiotrop
hoblasts may implicate beta 2-microglobulin in the transplacental tran
sport of IgG in conjunction with a recently identified class I HLA-lik
e receptor for IgG/Fc. Alternatively, beta 2-microglobulin may associa
te with a hitherto unidentified class I HLA molecule.