Alterations of N-glycan branching and expression of sialic acid on amniotic fluid alpha-1-acid glycoprotein derived from second and third trimesters of normal and prolonged pregnancies.
BACKGROUND
Alterations in the AGP glycoform pattern are not only disease related, but also can occur during physiological processes such as pregnancy. In this paper, possible changes in human amniotic fluid AGP glycan branching and in the type of sialic acid glycosidic attachment to glycans were analyzed with regard to different stages of human pregnancy.


METHODS
Crossed-affinity immunoelectrophoresis with concanavalin A was used to study AGP branching and lectin-ELISA with two agglutinins from Maackia amurensis and Sambucus nigra was applied to differentiate alpha2,3 and alpha2,6 type sialic acid attachments.


RESULTS
Despite almost unchanged levels of total amniotic fluid AGP during pregnancy, alterations in N-glycan branching and in the expression of sialic acid linkage on AGP were found to be associated with different stages of normal pregnancy. Amniotic fluid AGP glycans derived from third trimester compared with those from the second trimester had a higher percentage of tri- and tetra-antennary sialylated N-glycans. In the second trimester, sialic acid alpha2,6 linkage occurred twice as frequently as alpha2,3 linkage, while during the third trimester alpha2,3 linkage increased and both types of linkage appeared in equal proportion.


CONCLUSIONS
Branched and alpha2,3-sialylated AGP glycoforms in amniotic fluid could contribute to natural innate fetomaternal defense.
Orczyk-Pawiłowicz
Magdalena
M
Department of Chemistry and Immunochemistry, Wrocław Medical University, and Department of Obstetrics and Gynaecology, Clinic of Reproduction and Obstetrics, Wrocław, Poland.
Hirnle
Lidia
L
Katnik-Prastowska
Iwona
I
D000653:Amniotic Fluid / Q000737:chemistry / Q000378:metabolism*; D003208:Concanavalin A / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009961:Orosomucoid / Q000737:chemistry* / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011273:Pregnancy, Prolonged / Q000378:metabolism* / Q000473:pathology
D009961:Orosomucoid; D011134:Polysaccharides; D003208:Concanavalin A; D019158:N-Acetylneuraminic Acid