In article <36518D70.4518020A at gengenp.rug.ac.be>, Geert De Jaeger
<gejae at gengenp.rug.ac.be> wrote:
> Is cross reactivity possible between MHCI molecules and an T-cell which
> normally interacts with proteins presented on MHCII molecules?
from your posting it is not clear at which 'level' you define
cross reactivity. E.g. you might have a T cell that recognizes a
peptide bound to a defined class II molecule, but will be alloreactive
on class I or even recognize a defined peptide on class I.
And to which extent are you shure this T cell was selected on class II
in the thymus and not on class I, but has some crossreactivity
to class II (+ your peptide) ?
Anyhow, here are some references describing some similar phenomenon:
Macphail, S. and O. Stutman. 1987. L3T4+ cytotoxic T lymphocytes specific
for class I H-2 antigens are activated in primary mixed lymphocyte
reactions J Immunol .139:4007.
(describe CD4+ cells that are alloreactive to class I MHC molecules)
McKisic, M. D., A. J. Sant and F. W. Fitch. 1991. Some cloned murine CD4+
T cells recognize H-2Ld class I MHC determinants directly. Other cloned
CD4+ T cells recognize H-2Ld class I MHC determinants in the context of
class II MHC molecules J Immunol .147:2868.
(Title says it)
De Bueger, M., A. Bakker and E. Goulmy. 1992. Existence of mature human
CD4+ T cells with genuine class I restriction Eur J Immunol .22:875.
(describe one human CD4+ T cell recognizing H-Y in the context of class I).
One very interesting paper in this context is
Nanda, N. K. and Sercarz, E. E. (1995). The positively selected T cell
repertoire: is it exclusively restricted to the selecting MHC ? Int
Immunol, 7, 353-358.
(They show the existence of T cells, selected in the thymus on I-A, that
will recognise a specific peptide presented by I-E. Not as much as
your class II/I jump in specificity, but indicating in a system where
you know about thymic selection, that a once generated T cell
repertoire will allow some unexpected flexibility).
Good luck, jorg
Joerg Kirberg Tel. 0031 - 20 - 512 19 98
The Netherlands Cancer Institute FAX 0031 - 20 - 512 20 11
Div. Molecular Genetics (H4) E_mail kirberg at nki.nl
NL - 1066 CX Amsterdam