Does analysis of bronchoalveolar lavage fluid provide a tool to monitor disease progression or to predict survival in patients with HIV-1 infection?

Human immunodeficiency virus type I (HIV-1), the aetiological agent of the acquired immunodeficiency syndrome (AIDS), causes slow but progressive destruction of the immune system. In addition to the loss ofimmune function, HIV-infected patients manifest various infectious and noninfectious pulmonary complications. In particular, despite improvements in therapy, Pneumocystis carinii pneumonia (PCP) still remains the most common cause of morbidity and mortality in patients with advanced HIV infection.' Since the early years of the AIDS epidemic, analysis of bronchoalveolar lavage (BAL) fluid associated with transbronchial lung biopsy has been considered the procedure of choice for the evaluation of the full spectrum of pulmonary diseases throughout the course ofHIV-1 infection.2 Apart from its diagnostic role, the analysis of cells in BAL fluid has greatly increased our knowledge of the inflammatory events taking place in the pulmonary microenvironment, as well as the effects of retrovirus on the host lung defence mechanisms.3 In particular, taking advantage of the availability of monoclonal antibodies, cell culture facilities, and the cloning of a number of immunologically relevant genes (including those encoding for cytokines and cytokine receptors), researchers have recently elucidated mechanisms underlying the accumulation of inflammatory cells in the lung. Furthermore, the introduction of the polymerase chain reaction (PCR), which permits specific amplification of discrete DNA sequences, has increased detection of proviral sequences in BAL fluid samples, thus answering some basic questions related to the cellular pattern of infectivity and the mechanisms behind the spread of HIV-1 into the lung. Most studies of BAL fluid have contributed to the comprehension of events leading to the impairment of local immunocompetence. Recently, however, the attention of some groups has turned to defining the potential usefulness of BAL in providing prognostic information in patients with AIDS. In a time in which BAL has come of age, attempts are being made to correlate the cells (or cell products) in BAL fluid with clinical aspects of AIDSassociated interstitial lung disease. In an attempt to answer the provocative question raised in the title we will critically analyse studies claiming that BAL yields additional information predictive of diminished prognosis or survival for the patient infected with HIV-1. With the ultimate goal of confirming that the evolution of studies in this field continues on an appropriate track, we will also provide a framework for further investigation on the relation between immunological aspects of the interstitial inflammation and the respiratory disorders occurring as HIV-1 disease progresses. Finally, we will briefly summarise the first sets of observations covering the contribution of analysis of BAL fluid in monitoring treatment of AIDS-related pulmonary complications.