CONGENITAL INHERITED TOLERANCE (not ereditary)
and organ trasplants
Published by "EOS" Journal of immunology and immunopharmacology,
Vol. XXII - 2002 - n. 2. 40-43.
Abstract (11th Meeting European
Federation of Immunological Societies - Finland 1991)
The laws of histocompatibility (HC) tell that an only difference in the
Mayor Complex of HC (MHC) brings to a quick rejet of the transplant. The
laws of Snell affirm also that transplants from a parent (A or B) to a
hybrid F1(A x B) aren't rejected (III law of Snell). The contradiction
is only apparent.
An embryo become definitively tolerant for any extraneous antigen whit
whom it comes into contact with during the development. In the human fecundated
ovule there are: all paternal antigens (Ags) introduced by the spermatozoon;
all cellular maternal Ags + the antigenical specificities of the substances,
produced outside of the ovule (in the liver), stored as nutritive material
for the embryo. The precursors of the immunocompetent cells come, toward
the 20th day of the embryonic live, in the wall of the vitellicle sac
(Wolf's isles of blood) and for several days they are into direct contact
with the nutritive substances contained in it. The contacts continue through
the Cecal Appendix (demonstrable in the human embryo of 6 weeks) and in
the liver primordium (intra-embryonal haemopoiesis since the end of the
2nd month). For all these direct contacts the immunocompetent cells of
the embryo become tolerant toward all the histocompatibility-Ags of the
parents, also the one that are not genetically trasmitted as HLA-Ags.
We have the CONGENITAL INHERITED TOLERANCE (not ereditary), or TCE.
Pointing out for which parental Ags each son has become tolerant in embryo,
we have that from HLA-AB x HLA-CD come: F1AC-Tabcd; F1AD-Tabcd; F1BC-Tabcd;
F1BD-Tabcd (were T indicate the Ags tolerated for TCE) and it shows why
a son accepts transplants from the HLA-semicompatible parents (III law
In the Man the genes of numerous "minor histocompatibility sistems"
are dislocated on at least 12 cromosomes (over the 6th of the MHC): in
each of them we can get some meiotic genetical variations. These variations
make highly improbable a complete identity in the phratry, even in presence
of HLA identity. However in the phratry the tolerance as grown for the
favourable intervention of TCE as regards the parental Ags (TCE in common).
Conclusion: considering also the Mitocondrial Maternal Heritage, in
the organ transplants the elective donor is the mother.