gamma delta T cells are secondary participants in acute graft-versus-host reactions initiated by CD4(+) alpha beta T cells

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 expressing one or the two prototypic V beta gene families were negatively isolated from adult blood samples and injected into allogeneic chick embryos, CD4(+) alpha beta T cells expressing either V beta 1 or V beta 2 receptors were equally capable of inducing acute GVH reactions. consistent with the idea that alpha beta T cell alloreactivity is determined by CDR3 variability. By themselves. the gamma delta T cells were incapable of inducing GVH reactions. However. host gamma delta T cells were 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.