Rat transplantation antigens. V. A variation of the KCl-method releasing low molecular weight antigen

Extraction of soluble histocompatibility antigen from normal rat lymphoid cells by hypertonic salt (3 M KC1) releases high mol. wt material. It the original lymphoid cell suspension is washed more than once before extraction, antigenic acitivity disappears as measured by inhibition of cytotoxic antibody. This activity is mostly retained in the supernatants of the washing procedures. Extraction of these cell-free supernatants produced an antigenic material with a mol. wt of approximately 60,000. This suggests that at least part of the material accessible for KCl-extraction is released very early from the cell surface from the mechanical action, necessary for preparing the cell suspension.