A prodromal phase of infection with the human immunodeficiency virus (HIV). Laboratory criteria separating aids-related complex (ARC) from aids include elevated or hyperactive B-cell humoral immune responses, compared to depressed or normal antibody reactivity in aids; follicular or mixed hyperplasia in arc lymph nodes, leading to lymphocyte degeneration and depletion more typical of aids; evolving succession of histopathological lesions such as localization of Kaposi's sarcoma, signaling the transition to the full-blown aids.