Specificity of the Simultaneous Cell-mediated Immune Reactivity to RIII Murine Mammary Tumor Virus Glycoprotein 55 and Human Breast Cancer Tissues

The leukocyte migration test (LMT) reactivity of breast cancer patients to RIII murine mammary tumor virus (MuMTV) gp55 was studied and compared with simultaneous reactivity to the following: (a) RIII gp55 prepared in another laboratory; (b) gp68, gp34, and p28 of RIII MuMTV; (c) gp50 of A-strain MuMTV; (d) gp70 and gp45 of Rauscher leukemia virus; and (e) autologous and homologous lymphoreticuloendothelial (L-RE)-positive and-negative breast cancer tissues and extracts of MCF-7 tissue culture cells. LMT reactivity against the two gp55 preparations was essentially identical. A similar correlation was found in regard to LMT reactivity of L-RE-positive breast cancer patients, tested >11 months postoperatively against gp55 and autologous and homologous breast cancer tissues. Such a correlation was not demonstrable between LMT reactivity to gp55 and reactivity to other RIII MuMTV protein fractions, gp50 of A-strain MuMTV, Rauscher leukemia virus protein fractions, or L-RE-negative autologous breast cancer tissues. LMT reactivity to MCF-7 extracts was essentially limited to patients who were responsive to gp55. It appears that LMT reactivity of breast cancer patients to gp55 does not reflect a nonspecific increase in cell-mediated immunity randomly directed against glycoproteins and breast cancer tissue. To the contrary, it appears that the observed simultaneous LMT reactivity to gp55 and L-RE-positive breast cancer tissues reflects antigenic similarity in their cell-mediated immunity determinants. Information regarding the molecular nature of the cell-mediated immunity determinants should be of conceptual and clinical significance.