Modification of the graft-versus-host syndrome by anti-lymphocyte serum treatment of the host

The effect of administering anti-lymphocyte serum (ALS) to the F₁ hybrid recipient at various time intervals before and after the injection of parental donor cells has been investigated. The graft-versus-host (GVH) response can be completely inhibited by a single ALS injection given a short while before the injection of parental cells. ALS injected after the injection of donor cells fails to influence the GVH response.

It is considered that these studies confirm the view that ALS acts mainly on circulating lymphocytes and that a single ALS injection does not influence lymphocytes resident in spleen and lymph nodes.

Modification of the graft-versus-host syndrome by anti-lymphocyte serum treatment of the donor

Spleen and lymph node suspensions prepared from parental donor mice pretreated with four daily anti-lymphocyte serum (ALS) injections have been demonstrated to be incapable of inducing a graft-versus-host (GVH) syndrome when injected into F₁ hybrid recipient mice. A single ALS injection to the parental donor renders thoracic duct lymphocytes incapable of inducing a GVH response but the activity of spleen cell suspensions is retained.

It is suggested that this observation supports the view that ALS acts mainly on circulating lymphocytes.