Would anybody care to comment why activated T cells (human and rat)
express surface MHC class II molecules (Ia) ? If the role of Ia on B
cells is to present peptides to T helper cells in order to obtain
costimulatory signals (lymphokines), do T cells require cognitive help??
Some immunologists believe that cytotoxic T lymphocytes (CTL) need
signals from T helper cells to mature into killer cells. Do they receive
these signals directly by presenting peptide through their own Ia
molecules? What kind of peptides would be presented on the Ia of
activated T cells? One possibility would be peptides derived from their
T cell receptor molecules that would stimulate anti-idiotypic T helper
cells. What other kind of proteins would a T cell ingest to be able to
target into the endocytic pathway to produce Ia binding peptides? Do T
helper cells require help themselves? What happens in mice where no Ia
expression takes place in their activated T cells (although some claim
that they do)??
