Abstract
Lymphoid cells stimulated by soluble tumour antigens in the MCA-induced murine fibrosarcoma system have been identified by subclass and protective capacity in adoptive syngeneic hosts. Lymph-node or spleen cells taken at weekly intervals after inoculation of syngeneic chemically induced fibrosarcomas were enriched by 3 methods in T, B, and "null" cell subclasses, and assayed for proliferative kinetics in response to soluble membrane antigens. The stimulated subpopulations were found to be heterogeneous, their composition varying with time and tumour burden. Initial proliferative responses after tumour inoculation were limited to the T-enriched subpopulation. Later during tumour growth, T, B and null cell fractions were vigorously and equally stimulated by tumour antigen. The ability of the same T, B or null-cell subpopulations to inhibit tumour growth was measured in adoptive hosts by a modified Winn assay. Only the T-cell subpopulation responding to tumour antigen in vitro effectively and consistently retarded tumour growth in vivo. In contrast to the shared specificities on syngeneic tumours identified by the proliferative assay, tumour-growth inhibition was limited to the specific tumour borne by the cell donor.
Highlights
Summary.-Lymphoid cells stimulated by soluble tumour antigens in an MCAinduced murine fibrosarcoma system have been identified by subclass and protective capacity in adoptive syngeneic hosts
To determine which cells wiere responding to soluble antigens in vitro, normal and tumour-bearing spleen or lymph-node cells (LNC) suspensions were separated into subpopulations by 3 different methods: complementmediated cytolysis, nylon-wool columns and anti-mouse Ig (anti-Ig) columns
Spleen cells taken from tumourbearing and control animals at weekly intervals over a 4-week period of tumour growth were separated into T- and Benriched fractions by C'-mediated lysis
Summary
The mice, pooled, minced, and pressed through sterile 80-mesh stainless-steel screens. In all experiments soluble antigens were prepared from tumours of the same in vivo passage number as the tumours the experimental animals were bearing. "homologous" tumour antigens refers to the soluble preparation derived from the same tumour the experimental animals were bearing; "syngeneic" antigen refers to antigen prepared removed by resuspending the lymphoid cells in RPMI supplemented with 5% foetal calf serum (GIBCO) and passing the suspension dropwise through a sterile polypropylene funnel filled with glass wool (Pyrex Wool, Corning Glass Works, Corning, N.Y.) The efficacy of this procedure was tested by comparing carbon-particle phagocytosis of untreated spleen cells and cells from the same spleen passed once through glass wool. Antigen-induced 3H-dT incorporation in Nylon-wool column separation: T-enriched tumour-bearing cell populations (Forbes et spleen-cell fractions were eluted from nylonal., 1975). Two x the Winn procedure (1961) was used to test 108 spleen or LNC wvere incubated for 60 min specific anti-tumour activity of lymphoid at 37°C with the appropriate dilutions of tissues or their subpopulations.
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