I have been reviewing the literature on T cell epitopes mapped to viral
proteins, with an interest in finding out what eptitopes have been
shown to stimulate class II restricted T cell help in vivo. Most
papers use ex vivo T cell proliferation in response to synthetic
peptides as a measure of T helper cell function. It seems to me that a
tacit assumption is being made that CD8 cells are not contributing to
this proliferation, and my question is: why? and is this a correct
assumption? Should these results be taken at face value?
If one is immunized in vivo with whole protein antigen (viruses
efficiently stimulate class II and class I restricted cells), then PBMC
are isolated, peptide added and a cell proliferation assay performed,
is this strictly a measure of CD4 cell responses? Do CD8 memory cells
proliferate poorly or not at all in response to antigen or are they
generally present at a much lower frequency of antigen-specific memory
cells? Exogneous peptide can be used to map CTL function in
cytotoxicity assays, so both MHC responses should be present, I would
think.
Thanks in advance for correcting my ignorance.
David N. Levy
University of Alabama at Birmingham
Birmingham, AL
levy at uab.edu
