Effector and suppressor lymphoid cells in tumor‐bearing guinea‐pigs

Abstract

AbstractThe immune reaction of guinea‐pigs against their growing tumors was studied. Strain 13 guinea‐pigs were killed 2 weeks after SC implantation of the transplantable methylcholanthrene‐induced sarcoma (MC‐D), when the tumor was 2–3 cm In diameter. Spleen, lymph‐node, bone‐marrow and peripheral blood leukocytes (PBL), and subsets of spleen cells and PBL were mixed with lethal doses (105) of tumor cells and inoculated SC into normal recipients. Spleen, lymph‐node and bone‐marrow cells either enhanced or did not influence tumor growth, while PBL exerted a strong inhibitory effect. Normal spleen and normal PBL did not affect tumor growth. The spleen cells of tumor‐bearing animals were separated on nylon wool columns: the first fraction containing T cells was responsible for tumor enhancement, the second fraction containing predominantly non‐T (Ia+) cells inhibited tumor growth. Adherent cells had no effect. Similarly, after removal of T cells from the spleens with a specific rabbit antiserum or of non‐T cells plus a minor portion of T cells with an anti‐la serum (produced in strain 2 guinea‐pigs), the remaining cell population had, respectively, an inhibitory or an enhancing effect on tumor growth. By contrast, removal of either T or la+ cells from PBL eliminated their anti‐tumor effect. The major portion of splenic T cells formed EA rosettes. EA rosette‐positive cells were restricted to a minor portion of peripheral T lymphocytes. Thus, splenic and peripheral T cells from tumor‐bearing animals were different both functionally and according to their surface markers. It is hypothesized that Fc+ T cells are suppressors which are triggered by immune complexes.