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Developmental Immunology
Volume 5, Issue 3, Pages 169-182
http://dx.doi.org/10.1155/1998/46801

Epidermal Growth Factor Modulates Fetal Thymocyte Growth and Differentiation

1Department of Immunology, Basic Research Center, National Cancer Institute of Rio de Janeiro, Brazil
2Department of Biochemistry, Institute of Biology, Rio de Janeiro State University, Brazil
3Laboratory on Thymus Research, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil

Received 22 July 1996; Accepted 29 April 1997

Copyright © 1998 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In the present study, we used the fetal organ culture (FTOC) technique in order to study a putative effect of epidermal growth factor (EGF) on the thymus ontogeny. Functional EGF receptors and more recently the EGF molecule itself, respectively, on the membrane of epithelial components of thymic stroma and on a few thymocytes in adult thymus, had been reported in the literature. We could observe a dose-dependent decrease in cellularity and a progressive retention of thymocytes in the double-negative (CD4-/CD8-) stage of differentiation when exogenous EGF was added. Epidermal growth factor interfered with both fetal stroma growth and thymocyte development at a precise moment, that is, in the passage from double-negative to the double-positive (CD4+/CD8+) stage. After a 7-day FTOC in the presence of EGF, most cells recovered were Thy-1.2+, c-kit+, TSA1-/int, CD3-, and one of CD44high/CD25int, CD44-/CD25int, or CD44-/CD25-. Some developed into γδTCR+ cells with a mature (CD3+) phenotype, but not into αβTCR+ thymocytes. It seems that EGF addition makes the cultures "nonpermissible" for αβTCR+ thymocyte generation. We report here the presence of a high Mr "EGF-like" molecule on the membrane of fetal thymocytes, which role in the observed effects is under investigation. Further biochemical characterization of this molecule is still required, because its presence was only evidenced on the basis of its antigenicity.