Determination of idiotype-specific T cells in idiotype-vaccinated mice.
Immunoglobulin idiotypes (Id) of malignant B lymphocytes and plasma cells are tumor-specific antigens that were extensively used in immunotherapy studies. The effector mechanisms, involved in resistance to tumor following Id vaccination, are a controversial issue. Since cell-mediated responses, rather than antibody responses, constitute powerful effectors against tumors, recent studies focused on the generation of Id-specific T cells. Traditional methods for assessment of cellular responses in murine models of Id vaccination are inadequate because of their low sensitivity and because they do not determine actual frequency of antigen-reactive T cells. Here, we use the highly sensitive enzyme-linked immunospot (ELISPOT) assay for enumeration of interferon gamma (IFN-gamma)-secreting cells in Id-vaccinated mice. Our experimental model consists of the murine B-lymphocyte tumor 38C-13, which expresses surface IgM, and the plasma cell tumor D2, which secretes IgM with idiotypic specificity identical to that of 38C-13. Vaccination of mice with purified 38C-13 IgM induced resistance to 38C-13 as well as to D2 tumor cells. Although immunized mice produced high levels of anti-Id antibodies that bound to 38C-13 cells, no binding of antibodies to D2 occurred, suggesting that cellular mechanisms mediated resistance to the plasma cell tumor. ELISPOT assays revealed that immunization induced a significant increase in the frequency of Id-specific IFN-gamma-secreting T cells. Depletion of T cell subsets demonstrated that both CD4(+) and CD8(+) T cells were involved in the response to Id. This is the first report on application of the ELISPOT assay for enumeration of Id-reactive T cells in a murine model of Id vaccination, providing a tool to study Id-specific T cell responses and to evaluate the efficacy of Id vaccines.
Heyfets
Alina
A
Department of Human Microbiology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
Haimovich
Joseph
J
Hollander
Nurit
N
D000818:Animals; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology*; D019496:Cancer Vaccines / Q000276:immunology; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D008223:Lymphoma / Q000276:immunology; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014612:Vaccines / Q000276:immunology*
D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D014612:Vaccines; D007371:Interferon-gamma