Abstract
Absorption procedures which allow the production of a selectively cytotoxic anti-human lymphocyte serum are described. Although the production of a reagent whose reactivity is restricted. Although the production of a reagent whose reactivity is restricted exclusively to lymphocytes may be achieved by exhaustive absorption steps using fresh human erythrocytes, CML cells, and fetal liver cells, a more realistic alternative is the use of appropriately selected cultured human leukemia cell lines. Data are presented which show how these cell lines may be employed to selectively manipulate the cross-reactivity spectrum of ALS. Pre-treatment of donor bone marrow cells prior to transplantation with a selectively lymphocytotoxic ALS has been shown to allow transplantation of bone marrow across major histocompatibility barriers in rodents without the occurrence of GvH reactions, and it is the purpose of the present investigations to show that an analogous anti-human ALS can be prepared which possesses the required degree of selectivity to allow its application for human bone marrow transplantation.