Mycobacterium avium complex infection (MAC) is a major opportunistic infection in patients with AIDS. Disseminated MAC is a cause of significant morbidity and is an independent predictor of mortality. Current therapeutic and prophylactic regimens are only partially effective in eradicating MAC infection or preventing its occurrence. In this study, we will evaluate whether patients who are treated with the combination of Filgrastim and Rifabutin have enhanced ex-vivo killing of M avium and other opportunistic pathogens. This study will have clinical relevance because this regimen may be used as prophylaxis in AIDS patients who are at risk of developing MAC and other opportunistic pathogens.