In this report, we describe studies to examine the repertoire of freshly isolated human T lymphocytes to 400 distinct antigen fractions of Mycobacterium tuberculosis separated by a novel method involving two-dimensional gel electrophoresis. Separated antigens were probed with T cells from tuberculosis patients and purified protein derivative (PPD)-positive (PPD+) and PPD-negative (PPD-) contacts as well as normal healthy donors. T cells from all donors tested responded to separated antigens. Stimulation profiles for tuberculosis patients and PPD+ contacts were extremely heterogeneous, formally demonstrating that an enormous number of different antigens serve as targets of the cellular immune response to M. tuberculosis. Stimulation profiles for tuberculosis patients and PPD+ contacts were indistinguishable. However, stimulation profiles for tuberculosis patients and PPD+ contacts were easily distinguishable from those for PPD- contacts. Normal healthy donors showed T cell responses similar to those of either PPD+ or PPD- contacts.