SYNTHESIS OF IMMUNOGLOBlJUNS IgG, IgM AND IgA DURING TIlE ONTOGENY OF FOETAL PIGS

Franz J., A. Milon, H. Salmon: Synthesis of Immunoglobulins IgG, IgM and IgA during the Ontogeny of Foetal Pigs. Acta vet. Bmo, 51,1982: 23-30. Using the modified micro-ELISA (enzyme linked immunosorbent assay) on the competitive principle immunoglobulins IgG, IgM and 19A were demonstrated in the blood serum, amniotic fluid and organ suspensions of 50to 150-day old pig foetuses. The predominant immunoglobulin (Ig) in the blood serum and amniotic fluid of foetal pigs between 50 and 105 days of gestation was IgG. On the other hand, IgM prevailed in the suspensions of foetal organs up to 80 days of gestation. On the 105th day of gestation mutual ratios of the individual Ig classes in the suspensions of foetal organs, except the thymus, changed in favour of IgG. There were significant changes in the concentration ofIgG, IgM and 19A during the period under study. Foetal pig, IgG, IgM, IgA, ELISA. Transfer of proteins from dam to foetus has not been demonstrated in animals with the epitheliochorial placenta which include the pig (Sterzl and Silverstein 1967). Foetal pigs are therefore not affected by maternal immunoglobulins during their intra-uterine life. All serum proteins of foetal pigs are produced by the foetuses themselves and their immune response and, consequently, synthesis of immunoglobulins are therefore unaffected by the presence of maternal antibodies. For this reason, the foetal pig is an excellent model for studies of defence mechanisms in both human and veterinary medicine and has been receiving due attention as to the development of immunity. From a number of studies concerned with the incidence of immunoglobulins in foetal pigs and colostrum-deprived piglets (Sterzl et al. 1960; Franek et al. 1961; Sokol and i>urikovil! 1967; MenSik und Franz 1969; Proke§ova et a!. 1969, 1970; Porter 1969; Franz and MenSik 1971; Prokdova and Rejnek 1971, 1973; Bourne et a!. 1974) it appears beyond doubt that their sera contain immunoglobulins, though in low concentrations. However, up to now there has been no unequivocal answer to the question what are the quantities and mutual ratios of individual immunoglobulin (Ig) classes, depending upon the age of the foetus. The object of the present'study was to extend contemporary knowledge on the ontogeny of the synthesis of IgG, IgM and IgA by their quantification in the blood serum, amniotic fluid and suspensions of some organs of foetal pigs from 50 to 105 days of gestation. Materials and Methods Experimental Animals and Preparation of Samples for Analysis The experiment involved three groups of pig foetuses obtained by hysterectomy at 50, 80 and 105 days of gestation. Bach group comprised 24 foetal pigs of 3 litters (8 foetuses of each litter). Collection was made of the amniotic fluid, blood, liver, lungs, intestine, spleen and thymus of each foetus. Serum was prepared from the blood. Organ specimens were weighed and homogenized