Administration of chemotherapeutic agents or use of immunomodulating agents such as high dose corticosteroids, interferons, pentoxifylline, G-CSF/GM-CSF, erythropoietin, growth hormone and other growth factors within one month of enrollment. However, patients on anti-inflammatory drugs or stable doses of immunoglobulins (including hyperimmune immunoglobulin) will be eligible unless the latter are directed at a T-cell specific antigen.