BLOCKING CELLULAR DIVISION OF ACCESSORY/STIMULATOR CELLS
There are two situations in which inhibition of accessory or stimulator cell division should
be blocked. When purified T cells rather than unfractionated lymphoid populations are
used in Basic Protocol 1, cultures are frequently supplemented with accessory cells
syngeneic to the responder T cells. If accessory cell DNA synthesis is inhibited, one can
then be certain that the resultant proliferative response is comprised entirely of responder
T cells and does not contain a component of recruited B cell proliferation derived from
the accessory cell populations. In the MLR, the stimulator cells are spleen cells from mice
that differ from the responder cells in H-2 and/or Mls gene expression (see APPENDIX 1,
Tables A.1C.1 and A.1F.1) and they can also recognize alloantigens on the responder cells.
This responsiveness of stimulator cells against responder cells in an MLR (so-called
back-stimulation) must be prevented by blocking cellular division. This can be done by