Um. Abdelmotal et al., MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-I BINDING GLYCOPEPTIDES FOR THE ESTIMATION OF EMPTY CLASS-I MOLECULES, Journal of immunological methods, 188(1), 1995, pp. 21-31
Different forms of major histocompatibility complex (MHC) class I heav
y chains are known to be expressed on the cell surface, including mole
cules which are functionally 'empty'. Direct peptide binding to cells
is obvious during sensitization of target cells in vitro for cytotoxic
T lymphocyte killing and 'empty' MHC-I molecules are comparatively ab
undant on TAP-1/2 peptide transporter mutant cells, In the present wor
k we have estimated the fraction of 'empty' MHC class I molecules usin
g glycosylated peptides and cellular staining with carbohydrate specif
ic monoclonal antibodies. Synthetic D-b and K-b binding peptides were
coupled at different positions with different di- or trisaccharides, u
sing different spacing between the carbohydrate and the peptide backbo
ne. Binding of sugar specific mAbs was compared in ELISA and cellular
assays. An optimal D-b binding glycopeptide was used for comparative s
taining with anti-D-b and anti-carbohydrate monoclonal antibodies to e
stimate fractions of 'empty' molecules on different T lymphoid cells.
On activated normal T cells, a large fraction of D-b molecules were fo
und to be 'empty'. The functional role of such 'empty' MHC class I mol
ecules on T cells is presently unclear, However, on antigen presenting
cells they might participate in the antigen presentation process.