Cell-mediated immunity to histocompatibility antigens : controlling factors, with emphasis on Graft-versus-host reactions in mice

Graft-versus-Host (GvH) disease is characterized by weight loss, diarrhea, skin lesions, hypofunction of the immune system with concomitant infections, etc. This syndrome is potentially lethal. GvH reactions, which underly this disease, may occur when immunocompetent T lymphocytes are transplanted into a host, which is unable to eliminate the intrusive donor lymphocytes and which confronts the graft with a sufficient degree of histoincompatibility. The type of T lymphocyte which plays a central role in GvH reactions seems to be the Lyt-1+ T cell, which probably is analogous to the helper T cell. This cell type may activate other subsets of T lymphocytes, viz., cytotoxic T cells and suppressor T cells, which may lead to GvH disease, depending on the experimental conditions and antigenic differences between donor and host, The GvH reaction is not only interesting from the point of view of the ensuing syndrome, but can also be used to study certain fundamental immunological problems, such as which histocompatibility antigens evoke the strongest immune reactions, which cell types are involved, do these cell types synergize, etc. We approached these questions in experimental studies with mice. To study such problems one has to have an appropriate assay. We made use of a delayed-type hypersensitivity (DTH) assay which is appropriate to measure the anti-host immune reactivity during acute and delayed GvH reactions in mice