Macrophage migration inhibition with mouse tumor antigens: Properties of serum and peritoneal cells during tumor growth and after tumor loss

Immunity to Murine Sarcoma Virus Induced Tumours. III. Analysis of the Cell Populations Involved in Protection from Lethal Tumour Progression of Sublethally Irradiated, MSV Inoculated, Mice

“…Hellstrom (1969, 1970) have suggested that during the progressive phase of growth of the MSV induced sarcoma, anti-tumour immunity in vivo is blocked by factors in the serum, perhaps antigen-antibody complexes (Sjogren et al, 1971). The suggestion was made that these blocking factors themselves provided the environment which allowed tumour growth in the face of anti-tumour directed immunity (Halliday, 1972;Hellstrom, 1969,1970;Baldwin, Price and Robins, 1972). In an analogous fashion, it has been suggested that a cell which blocks T lymphocyte activity in a nonspecific manner may be in some way be responsible for tumour progression (Gorczynski, 1974c).…”

“…If similar effector cell types are responsible for activity in vitro and in vivo, the anomalous behaviour of progressor spleen cells in vitro may be due to an inhibition of activity which has little physiological significance, whether the inhibition is specific Hellstrom, 1969, 1970;Halliday, 1972) or nonspecific (Gorczynski, 1974c). However, the data of Table IV suggest an alternative explanation, namely, that in the adoptive transfer system used to investigate immunity in vivo, there is less likelihood of the cell contact necessary for inhibition, and this likelihood is increased by merely increasing the number of " suppressor " cells inoculated.…”

“…Blocking by serum factors is of an antigen specific type (Hellstr6m andHellstrom, 1969, 1970;Halliday, 1972). It is quite feasible that both types of suppression could be encompassed within the same model, perhaps even being caused by similar molecules .…”

“…While the tumour is in a regressing phase, or after tumour regression, cells can be detected which are capable of killing MSV tumour cells, or recognizing antigens expressed by those cells and then reacting in other immunological tests. In these latter assays (Gorczynski, 1 974b, c;Halliday, 1972) the reactive cells are T lymphocytes. When the tumour is in a progressive phase of growth such effector cells are detected less readily.…”

“…When the tumour is in a progressive phase of growth such effector cells are detected less readily. Indeed, there is evidence that serum factors exist at this time in progressor animals which can block the in vitro assays of cell mediated immunity Hellstrom, 1969, 1970;Halliday, 1972). It has also been reported that such " progressor animals " have in their spleen and lymph node organs a cell type capable of suppressing even the nonspecific T lymphocyte response to the mitogen phytohaemagglutinin, PHA (Gorczynski, 1974c).…”