GAMMA-DELTA T-CELLS ARE SECONDARY PARTICIPANTS IN ACUTE GRAFT-VERSUS-HOST REACTIONS INITIATED BY CD4(-BETA T-CELLS() ALPHA)

To examine the role of T cell subpopulations in an acute graft-versus- host (GVH) reaction. gamma delta T cells and alpha beta T cells expres sing one or the two prototypic V beta gene families were negatively is olated from adult blood samples and injected into allogeneic chick emb ryos, CD4(+) alpha beta T cells expressing either V beta 1 or V beta 2 receptors were equally capable of inducing acute GVH reactions. consi stent with the idea that alpha beta T cell alloreactivity is determine d by CDR3 variability. By themselves. the gamma delta T cells were inc apable of inducing GVH reactions. However. host gamma delta T cells we re recruited into the donor alpha beta T cell-initiated lesions. where they were activated and induced to proliferate. The data suggest that gamma delta T cells may play a secondary role in GVH reactions.