Marked tumor regression in advanced vaginal cancer was induced by adjuvant therapy with the biological response modifier sizofiran (SPG) in a 94-year-old woman. SPG was repeatedly injected into the tumor. To examine the relationship between tumor cell expression of human leukocyte antigens (HLA) and lymphocytic infiltrates in tumor tissues, we performed immunohistochemical examinations using monoclonal antibodies to HLA-ABC, HLA- DR, Leu2a, Leu3a, and Leu4. HLA-DR expression, which was not seen before the administration of SPG, was positive with the repeated SPG injections. The subsets of Leu4(CD3)-positive cells and Leu3a(CD4)-positive cells increased markedly as the infiltration advanced. These findings suggest that repeated intratumoral injection of SPG may enhance cell-mediated immune response via an increase in the expression of HLA-DR antigens.
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