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Abbreviations: CF = cystic fibrosis; CFTR = cystic fibrosis transmembrane conductance regulator; IL = interleukin; IRF = interferon regulatory factor; LPS = lipopolysaccharide; RT-PCR = reverse transcriptase-polymerase chain reaction Respiratory [...]

Human immunodeficiency virus (HIV) infection has been associated with a number of hepatic and biliary tract disorders. Case reports, series of liver biopsies, and postmortem studies that examined the hepatobiliary system were retrieved with a MEDLARS search and form the basis of this review. The liver and biliary tract are frequently involved with opportunistic infections (most commonly mycobacteria and cytomegalovirus) and neoplasms (mainly Kaposi's sarcoma) in patients with HIV infection. The patients are often asymptomatic but may have elevated levels of serum liver enzymes. these abnormalities are nonspecific. Sulfa drugs, pentamidine, and ketoconazole are the medications used in HIV-related infections that are most likely to results in abnormalities on liver tests. Acalculous cholecystitis and sclerosing cholangitis also occur in HIV infection. Cytomegalovirus and Cryptosporidium are the organisms most commonly associated with these conditions. Imaging studies of the liver may defect parenchymal abnormalities and guide liver biopsy. The role of this procedure in the diagnosis of opportunistic infections and neoplasms is controversial because these lesions are generally disseminated at the time liver abnormalities are evident. A liver biopsy is best used when other less invasive procedures have failed to provide a diagnosis. Endoscopic retrograde cholangiopancreatography is a useful diagnostic procedure with therapeutic potential in patients with abdominal pain, fever, or an elevated serum alkaline phosphatase level.

Several changes in the past decade have caused clinicians to modify the ways they treat infections in children with cancer. These include changes in the predominant microorganisms that cause infections in immunocompromised children (in particular, an increase in the proportion of infections caused by gram-positive pathogens); the introduction of new classes of antibiotics; and the greatly increased number of children who undergo chemotherapy and other immunosuppressive treatments. The consequence of this latter development is that children with cancer spend longer periods with reduced numbers of white blood cells (neutropenia), during which time they are particularly vulnerable to infections by a variety of agents. Part II of this review will be published in the December 1991 issue of The Journal of Pediatrics and will discuss the treatment of fungal and viral infections in children with cancer. Topics reviewed in this article include: the initial evaluation; patients with indwelling intravenous catheters; selection of the initial antibiotic regimen; the role of vancomycin (an antibiotic effective against gram-positive infections); other new antibiotics; prolonged granulocytopenia (one week or longer); changes in antibiotic therapy during granulocytopenia; and empiric treatment for fungal infections. Most preventive strategies concerning immunocompromised patients have focused on bacteria, because they are responsible for most infections in such hosts. Careful hand washing by health care staff is of paramount importance. Other preventive techniques include mechanical protection and the use of oral antibiotics and antifungal drugs. Drugs for preventing viral or parasitic infections are also mentioned. Patients' immune capabilities can be improved by passive immunization (administration of antibodies) for high-risk patients; administration of cytokines or lymphokines (factors produced by cells of the immune system); or administration of granulocyte-macrophage or granulocyte colony-stimulating factor (both stimulate the rate of development of mature blood cells). (Consumer Summary produced by Reliance Medical Information, Inc.)

Infection with the human immunodeficiency virus type 1 (HIV-1) is associated with various abnormalities of the immune system, including a decrease in a class of white blood cells known as CD4+ T lymphocytes. HIV disease is often complicated by opportunistic infections, which develop as a result of the weakened immunity of the patient. The risk of opportunistic infections is directly related to the CD4+ count in adults, suggesting that these immune cells may be involved in the development of opportunistic infections. Studies show that progressive deterioration of T helper (Th) cell function precedes the critical loss of CD4+ cells and predicts the development of AIDS. The pattern of loss in Th function, and the relation between Th function and risk of opportunistic infections were assessed in 34 HIV-1-infected children. Th function was evaluated by measuring the production of interleukin-2, a growth factor, by helper T cells after exposure to: (1) 'recall' antigens, such as influenza virus or tetanus toxoid; (2) allogeneic human leukocyte antigens (HLA), which are proteins found on all cells and can cause immune responses; and (3) phytohemagglutinin (PHA), a plant substance that causes red blood cells to clot. There were four patterns of Th function: response to all stimuli, which was observed in 34 children; a lack of response to recall antigens, in seven children; response only to PHA, in seven children; complete lack of response to any stimuli, in 13 children. The incidence of opportunistic and bacterial infections was greater in children with impaired Th function than in children with normal Th function. The findings show that distinct patterns of Th function loss occur in HIV-1-infected children and correlate with a greater frequency of infections. Evaluation of Th responses to antigens and PHA may help to monitor the progression of HIV disease. (Consumer Summary produced by Reliance Medical Information, Inc.)