Pregnancy-associated glycoprotein (PAG) antibodies are immunological tools used to detect and study PAGs, a family of placenta-specific proteins critical in reproductive biology. First identified in ruminants in the 1990s, PAGs are secreted by trophoblast cells during pregnancy and are implicated in maternal-fetal communication, immune modulation, and placental development. While their exact physiological roles remain partially unclear, PAGs are hypothesized to regulate protease activity, hormone interactions, or immune tolerance to sustain pregnancy.
Structurally, PAGs belong to the aspartic proteinase family but exhibit limited enzymatic activity due to evolutionary mutations. This loss of catalytic function suggests a shift toward signaling or binding roles. Antibodies targeting PAGs enable researchers to quantify these proteins in maternal blood or placental tissues, facilitating pregnancy diagnosis in livestock (e.g., cattle, goats) and reproductive research. Commercial PAG-based pregnancy tests are widely used in veterinary medicine for early detection.
In humans, PAG-like proteins (e.g., PAPPA) are associated with pregnancy disorders like preeclampsia, spurring clinical interest. Cross-species studies using PAG antibodies highlight conserved and divergent functions, aiding evolutionary insights. Ongoing research focuses on elucidating PAG interactions with maternal systems, their diagnostic potential in gestational pathologies, and applications in improving reproductive management in agriculture and medicine.