1302 Cell Immunity in Graft Rejection

Measurement of cel l -mediated cytotoxic i ty (CMC) 1 directed to cell surface antigens has been faci l i ta ted by the e laborat ion of a re la t ively simple reproducible test in which ~lCr is released from labeled target cells (1-5). Other invest igators have examined certain facets of the test (6-18) and have appl ied the technique to studies of tumor allograft systems (3-5, 16, 19, 20) and soluble antigens bound to the surface membrane of ta rge t cells (18, 21-26). The purpose of this s tudy was to detect the appearance of cytotoxic lymphocytes (CL) in spleens and draining lymph nodes of ra ts graf ted with allogeneic skin b y means of a modified 51Cr release assay and to quan t i t a t e CMC during rejection and prolonged survival of allografts induced by enhancing antibodies. Wi th 5~Cr-labeled embryonic fibroblasts (EFB) as ta rge t cells der ived from donor s t ra in ra ts tha t were the source of immunizing skin grafts, and with cytotoxic lymphoid cells from sensitized recipients, the level of cellular immuni ty could be determined in recipients of skin allografts.