The syndrome of idiopathic CD4+ lymphocytopenia.

The syndrome of idiopathic CD4+ lymphocytopenia has recently been recognized and referred to as the persistent depletion of peripheral blood CD4+ T lymphocytes below 300 cells per cubic millimeter or less than 20% of total lymphocytes in the absence of either HIV infection or other known causes of immunodeficiency. The available literature indicates that neither human retroviruses (HIV-1, HIV-2, HTLV-I, HTLV-II) nor other transmissible agents play any clear-cut role in the pathogenesis. Furthermore, the epidemiologic, immunologic and clinical features of this syndrome differ substantially from those of HIV infection. The heterogeneity of both immunologic abnormalities, in addition to CD4+ depletion, and clinical course in patients with this disorder points out no common cause although in at least a subset of patients the pathogenetic pathways could be shared with common variable immunodeficiency.