In article <3rlheu$r8i at jhunix1.hcf.jhu.edu>, ejf at welchlink.uoregon.edu (Ephraim Fuchs) writes:
> Dr M.R. Clark (mrc7 at cus.cam.ac.uk) wrote:
>> : I accept fully that the logical way out of this is to say that a naive B-cell
> : presents for tolerance. However what about activated B-cells undergoing somatic
> : hypermutation. Experimental evidence shows us that activated B-cells make
> : highly efficient antigen presenters. So how do you deal with altered
> : specificity
> : and idiotype during hypermutation?
>>> The solution that Polly Matzinger and I have arrived at is that both
> resting and activated B cells are tolerogenic APCs for naive but not
> memory T cells. We believe that all experiments showing activated B
> cells as good APCs used responder T cells that contain some memory cells
> (even from T cell receptor transgenic mice).
>> By not allowing naive T cells to become activated by antigens presented
> by B cells, the idiotype presentation problem is avoided.
>> Ephraim Fuchs
>ejf at welchink.welch.jhu.edu>>Ron Schwarz presented some very convincing data at the Taos dendritic cell
meeting in March. If I remember (I don't have notes to hand), he used T cells
rigorously selected for markers of "naievety" from TCR TG mice, and used
limiting dilution assays to determine the frequency of responding T cells with
increasing numbers of APC. He showed that activated, but not resting B cells
were effective APC for naive T cells, but that they were less effective than
dendritic cells on a cell-to-cell basis.
Gordon MacPherson
macpherson at molbiol.ox.ac.uk
