Immunodeficiency and its relation to lymphoid and other malignancies.

The reasons why immunodeficiency leads to malignant disorders are multifactorial. The overall incidence of malignancies in persons infected with the human deficiency virus (HIV) is estimated to be 40%. Other infecting agents, especially herpesvirus species, play a pivotal role in HIV-associated non-Hodgkin's lymphoma (NHL) and Kaposi's sarcoma (KS). Mucosaassociated lymphatic tissue (MALT) lymphoma in the stomach may be a result of a chronic gastritis caused by Helicobacter pylori, a gram-negative bacterium. The Epstein-Barr virus (EBV) genome can be found in a high percentage of lymphoma cells of HIV-NHL (nearly 100% in the primary lymphoma of the CNS and about 50% in all other lymphoma entities). In body-cavity based NHL, characterized by the absence of EBV and c-myc oncogen, sequences of a herpesvirus were identified which corresponds to the gamma-herpes viremia found in KS. The Kaposi's sarcoma-associated herpesvirus (KSHV) was usually present in primary-effusion lymphoma (PEL). HIV-infection, which causes multiple dysfunctions within the immune system, triggers the cytokine dysregulation. An abnormal endogenous interferon (IFN)-alpha production is observed in HIV-infected patients with KS, especially in the later natural course of the disease. A monitoring of the IFN-system by MxA, a protein specifically induced by IFN's of type I, may be a necessary stratum of identifying patients who show superior effects and the greatest clinical benefit from treatment with IFN-alpha.