Detection of Breast Tumor Antigen-sensitive Circulating T-Lymphocytes by Antigen-stimulated Active Rosette Formation^1,2

Preoperative circulating human breast tumor-associated antigen (BTA)-sensitive T-lymphocytes were detected in breast carcinoma patients by the antigen-stimulated active rosette-forming T-cell (AgARFC) assay. Incubation of peripheral lymphocytes isolated from tumor-bearing patients with either of two soluble allogeneic BTA extracts (BTA₁ and BTA₂) produced higher percentages of AgARFC than did incubation in antigen-free media (ARFC). The circulating BTA-sensitive T-cell subpopulation, as %AgARFC — %ARFC, of 56 patients found to have invasive breast cancer was 6.4 ± 0.9% (S.E.) for BTA₁ and 7.4 ± 0.7% for BTA₂. These values were significantly higher than the mean responses to corresponding isologous lymphocyte histocompatibility antigen (HA) extracts (HA₁ and HA₂), 1.1 ± 0.5% for HA₁ and 2.2 ± 0.8% for HA₂ (p < 0.001). In contrast, mean AgARFC responses of lymphocytes from patients with benign mastopathy to BTA or to HA were not significantly increased. The means of paired BTA-HA differences in %AgARFC response for 56 breast carcinoma patients were significantly higher than values obtained for 87 patients with benign mastopathy (p < 0.001), for 16 patients with nonmammary carcinomas (p < 0.001), or for 18 clinically normal subjects (p < 0.001). Similarly, significant differences were found for the corresponding absolute numbers of circulating BTA-sensitive T-cells per cu mm of peripheral blood. Differences in peripheral lymphocyte counts, total T-cell levels, and ARFC levels were not highly significant in any of the groups of patients studied. The AgARFC assay provided a specific, rapid, and reproducible assay for detecting peripheral blood T-lymphocyte sensitized to BTA in breast cancer patients.