Specificity of tumor antigen recognition by T-lymphocytes in the leukocyte adherence inhibition (LAI) assay in patients with breast cancer

In an attempt to enhance the specificity with LAI assay in the diagnosis of cancer, we explored the possibility of using highly purified, ⁵¹Cr-prelabeled-PBL-subpopulations in performance of the assay. Leukocyte separation was achieved in 2 stages which involved E(AET) rosetting for the isolation of T-lymphocytes followed by Percoll gradient for separation of monocytes. These procedures provided excellent cellular yield, viability and cellular enrichment. By comparing the reactivity of various isolated subpopulations from breast cancer patients we established the critical role of T-lymphocytes in the recognition of tumor antigen in the LAI reaction, i.e. T-lymphocytes exhibited a breast cancer extract-specific response, reflected in a significant reduction of leukocyte adherence, while B-lymphocytes did not respond. In contrast, monocytes of breast cancer patients showed a non-specific LAI response to several unrelated tumor extracts. Similarly, T-lymphocytes from all patients with benign breast diseases as well as from healthy subjects showed no LAI response while false positive responses were detected in the unseparated PBL and monocytes of these individuals. It is concluded, therefore, that a differential diagnosis of cancer can only be made if isolated T-lymphocytes from PBL are used in the LAI assay procedure.