Inflammatory competence of fetal rat: acute-phase plasma protein response of the fetus treated by turpentine in utero.

Using crossed immunoelectrophoresis, immunoelectrodiffusion, autoradiography, and equilibrium binding techniques, we demonstrate that the rat fetus, directly challenged in utero at 18 days by a single subcutaneous turpentine injection, presents a complex acute-phase plasma inflammatory response. A number of fetal serum proteins, 48 h after the injection, increase in concentration by factors of about 2-5. These positive acute-phase reactants (APR) are alpha 1-acute-phase globulin (alpha 1-AP), alpha 2-macroglobulin (alpha 2-M), alpha 1-acid glycoprotein (alpha 1-AG), haptoglobin (Hp), and hemopexin (Hpx). A number of proteins decrease, behaving like negative APRs. These are albumin, alpha 1-fetoprotein (AFP), transferrin, GHR-P63, thyroxine-binding prealbumin (TBPA), and transcortin (CBG). The marked fall in concentration of two of the high-affinity hormone-binding proteins of the fetal rat, i.e., the estrophilic AFP and TBPA, induce significant decreases (by 25-40%) of the estrogen- and thyroxine-binding abilities of the fetal serum. While the plasma inflammatory response of the fetus is qualitatively similar to that of the adult, the fetal reactions are, as a rule, quantitatively weaker. The characteristics of the plasma inflammatory response of the fetus are discussed in relation to the highly dynamic state of its development.