- Current or recent (<3 mos) treatment with any immunosuppressant medications (including but not limited to monoclonal antibodies to B and T cells, anti-TNF agents, glucocorticoids, antimetabolites (azathioprine, 6-mercaptopurine), calcineurin inhibitors (tacrolimus, cyclosporine), mycophenolate mofetil). Subjects who are otherwise immunocompetent and have discontinued any immunosuppressant medications 3 or more months prior to enrollment may be eligible to enroll.