The influence of T-lymphocyte precursor cells and thymus grafts on the cellular immunodeficiencies of the BB rat.

To determine whether abnormal T-lymphocyte precursor cells or an abnormal thymus is responsible for the immunologic deficiencies of spontaneously diabetic BB rats, thymus grafts or T-cell-depleted bone marrow cells were exchanged between diabetes-prone and non-diabetes-prone animals. Analysis of peripheral lymphocyte populations from these recipients with monoclonal antibodies, a fluorescence activated cell sorter, and mixed lymphocyte culture tests indicate that an abnormal thymus is not responsible for the immunodeficiency of BB rats, but that the defect resides within the lymphocyte precursor pool.