Tuberculosis (TB) Screening for the Diagnosis of Latent TB in Immunocompromised Populations

Inclusion Criteria: Inclusion criteria for the study are broad. * Participants can be enrolled regardless of race, gender, risk of exposure to TB, metabolic disorders or coinfection with non-TB agents. * Only participants who have provided written informed consent will be included. * Patients belonging to the four following groups will be considered eligible for tuberculosis screening and inclusion in the T-SPOT ELISPOT study: * Patients with end stage renal disease receiving hemodialysis or peritoneal dialysis; * Recipients of solid organ transplants; * Recipients of, or candidates for, an allogeneic stem cell transplant for hematologic malignancies; * Patients with rheumatologic diseases (e.g., systemic lupus erythematosus \[SLE\], rheumatoid arthritis, psoriasis) who are receiving, or about to receive, immunosuppressive therapy, including corticosteroids and anti-TNF alpha inhibitors. Exclusion Criteria: * Individuals who have not signed an informed consent * Hemophiliacs or individuals who, on the advice of the enrolling physician, may otherwise be at increased risk of an adverse reaction to venipuncture or tuberculin skin test administration