Immunosuppression by a mouse tumor resembles antigenic competition

Area of Science:

• Immunology
• Oncology
• Cellular Biology

Background:

• The immune system can be suppressed by certain stimuli.
• Antigenic competition describes the phenomenon where one antigen can inhibit the immune response to another.
• Tumor cells can influence host immune responses.

Purpose of the Study:

• To investigate the effect of P-815 tumor cells on the immune response to sheep erythrocytes.
• To compare the immune suppressive effects of tumor cells with known antigenic competition.

Main Methods:

• Mice (syngeneic or allogeneic) received intraperitoneal injections of gamma-radiated, UV-radiated, or unradiated P-815 tumor cells.
• A subsequent intraperitoneal injection of sheep erythrocytes was administered.
• The immune response to sheep erythrocytes was measured and compared between groups.

Main Results:

• Intraperitoneal injection of P-815 tumor cells, regardless of radiation treatment, suppressed the immune response to sheep erythrocytes.
• This suppression was comparable to that observed with horse erythrocytes, consistent with antigenic competition.
• Maximal suppression occurred when sheep erythrocytes were injected intraperitoneally several days after tumor cells, at a dose of 10(8) or less.

Conclusions:

• P-815 tumor cells can induce immune suppression in mice.
• Tumor cell-induced immune suppression shares mechanisms with antigenic competition.
• The route, timing, and dose of antigen administration are critical factors in the observed immune suppression.