Pulmonary Disease in the Acquired Immune Deficiency Syndrome

T he acquired immunodeficiency syndrome (AIDS) is the most recent addition to the long list of primary and secondary immune deficiencies. Unfortunately, it has rapidly become the most common immune deficiency diagnosed in the United States today. Between the first report in 1981 and early 1984, over 3,000 cases of AIDS were recorded by the Centers for Disease Control.’ This article reviews the major features of the immune deficiency in AIDS, as well as the diagnosis and treatment of pulmonary manifestations occurring in the setting of this newest immune deficiency state. AIDS is defined by the Centers for Disease Control as the occurrence of a disease indicative of underlying cellular immune deficiency in persons without prior history of immunologic abnormality. The most common diseases which fit this definition are Kaposi’s sarcoma before age 60, Pneumocystis carinii pneumonia, and one or more other serious opportunistic infections. Pneumocystis pneumonia is the presenting manifestation in over 50 percent of AIDS cases.2 The overall case-fatality rate for AIDS is approximately 40 percent; however, the two-year mortality for patients who have experienced one or more opportunistic infections is in excess of 90 percent.2 While most cases have occurred in the United States, many cases have been reported from Western Europe, mostly in homosexual and bisexual males with the past history of sexual contacts from the United States. In addition, cases of AIDS are being reported with increasing frequency among heterosexual males and females in Haiti and Zaire. Groups recognized to be at increased risk include homosexual and bisexual males, intravenous (IV) drug users, hemophiliacs, Haitian immigrants, and sexual contacts of the above groups. The nature of the groups recognized to have an increased risk for developing AIDS suggests strongly that this immune deficiency has an infectious etiology. The available epidemiologic evidence points to an infectious agent transmissible by sexual contact, shared needle use, or blood. The putative AIDS agent has not been identified to date, recent studies point to involvement of double-stranded RNA viruses (retroviruses) of which the human T cell leukemia virus is the prototype of man.3 In view of its probable viral etiology, AIDS should be classified as a secondary immune deficiency. Patients with AIDS may have Pneumocystis pneumonia, Kaposi’s sarcoma, or other serious opportunistic infections. Fever of unknown origin (FUO) associated with diarrhea and 9-kg weight loss is a common presenting syndrome. In many patients with FUO, thrush or Pneumocystis develops within several weeks or months. It is well recognized that patients with AIDS who have Kaposi’s sarcoma often subsequently have opportunistic infections. Thus, a high index of suspicion for Pneumocystis pneumonia is warranted in AIDS-Kaposi sarcoma patients in whom cough and dyspnea develop. Another syndrome designated as the lymphadenopathy syndrome or AIDS-related complex (ARC) has recently been identified in the same population groups at increased risk for AIDS . Most patients are homosexual or bisexual males with chronic lymphadenopathy, sometimes associated with low-grade fevers and night sweats. Mild to moderate immunologic abnormalities are usually present, linking the syndrome with AIDS. It is clear that some patients with the ARC syndrome have progressed to AIDS during prospective follow-up; however, the true incidence of such progression will require many years of study. Two other illnesses that appear to be related to AIDS include idiopathic thrombocytopenic purpura (ITP) in young males,6 non-Hodgkin’s lymphoma, and possibly Hodgkin’s disease. Numerous functional and phenotypic abnormalities of the immune system are found in AIDS. The most significant defects involve cell-mediated immunity as evidenced by the spectrum of viral, fungal, protozoan, and mycobacterial infections. The most characteristic feature in established AIDS is depletion of helper T cells, as enumerated with the monoclonal antibodies OKT4 or Leu 3 47 The numbers of suppressor/cytotoxic cells are normal to increased. Elevated levels of IgG and IgA are frequently observed; however, primary antibody responses may be defective, a point