MALIGNANT T LYMPHOBLASTS BIND HUMAN IMMUNOGLOBULIN (Ig)

Human sera were tested by indirect immunofluorescence (IF) for antibodies to cells from 2 malignant T cell lines. By direct IF, these cells, like normal T cells, lacked surface Ig. However, when incubated with normal sera and then treated with fluoresceinated polyvalent anti-Ig, many cells showed patchy surface fluorescence, while similarly treated normal T cells from thymus and peripheral blood were negative, Surface fluorescence was also seen when malignant T cells obtained directly from 2 children with lymphoblastic lymphoma were first incubated in their own sera as well as in control sera. This indicates that positive staining reactions were not necessarily due to alloantibodies. Reactivity seemed related to serum Ig levels since negative or diminished reactions were seen with sera from many newborns and from patients with agammaglobulinemia, while sera from newborns with antenatal infections and elevated Ig levels gave positive reactions. When, following serum treatment, cells were stained for IgG, IgA and IgM, some sera resulted in positive staining for only one Ig class, whereas other yielded positive staining for 2 or all 3 immunoglobulins. These findings suggest that malignant T lymphoblasts differ from normal T cells by possessing surface receptors for Ig. These receptors may represent tumor-related antigens recognized by both the tumor host and by most normals.