Secretory Component, J Chain, and Immunoglobulins in Human Embryos and Fetuses of the First Trimester of Pregnancy: Immunohistochemical Study

Byline: Pavel Gurevich (), Asher Elhayany (), Herzl Ben-Hur (), Moisey Moldavsky (), Sergio Szvalb (), Judit Zandbank (), David F. Schneider (), Itshak Zusman () Abstract: In our previous studies, we described the development of the secretory (mucosal) immune system (SIS) in human fetuses in the second trimester of pregnancy. In the present study, we examined the presence and distribution of components of this system in human embryos and early fetuses in the first trimester. An immunohistochemical study was performed on 17 embryos and 9 fetuses (4 to 12 wk of development) using antibodies against secretory component (SC), joining (J) chain, immunoglobulins (IgA, IgM, IgG), subsets of T and B lymphocytes, and macrophages. Cells positive for SC, J chain, and IgG were found in epithelial tissues from wk 4 of pregnancy. In the internal organs, such as the myocardium and endocardium, capillary endothelium, epithelium of the kidney tubules and some others, only J chain and immunoglobulins were seen. IgA was weakly reactive in tissues where SC and/or J chain were presented. IgM was very weak or absent. Among the cellular components of the SIS, only macrophages were seen in 4-wk-old embryos. CD3+ and CD20+ lymphocytes were found at wk 7 to 8. IgA- and IgM-positive lymphocytes appeared at the end of wk 9. The SIS is widespread in embryonic and early fetal periods and begins to function before the appearance of the common immune system in the developing organism. The first functional components of the SIS, such as IgG and IgA observed in this study, are most probably of maternal origin. Author Affiliation: () Laboratory of Experimental Medicine, Institute of Pathology, Assaf Harofeh Medical Center, 12B Hamada Street, Park Rabin, Rehovot 76100, Israel, IL () Central District, Clalit Health Services, Rishon Leziyon, Israel, IL () Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Tserifin, Israel, IL () Department of Pathology, Rebecca Sieff Hospital, Safed, Israel, IL () Institute of Pathology, Assaf Harofeh Medical Center, Tserifin, Israel, IL () Koret School of Veterinary Medicine, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Box 12, Rehovot 76100, Israel, IL Article History: Received Date: 28/12/2001 Accepted Date: 14/03/2002