A 15-year-old girl is scheduled to receive radiotherapy for a spinal tumor. The neoplastic cells of her tumor express T-lymphocyte receptor genes but do not express CD4 or CD8. Which of the following is the normal counterpart of these malignant cells?
Immunoglobulin-secreting plasma cells in bone marrow
Regulatory T cells
Early T lymphocytes in thymic cortex
Late T lymphocytes in thymic cortex
T lymphocytes in thymic medulla
