Tissue Biopsy and Imaging Studies in HIV-Infected Patients

This study will examine tissue from the tonsils, lymph nodes and large bowel of HIV-infected patients to investigate changes in viral load and certain white blood cells during treatment. Normal volunteers and HIV-infected patients 18 years of age or older may be eligible for this study. Candidates will be screened with a medical history, physical examination, blood and urine tests and possibly an electrocardiogram (EKG). Blood tests may include HLA typing, a genetic test of immune system markers. Participants may undergo the following procedures: * Blood tests (patients and volunteers) * Biopsies The frequency of biopsies for given patients may vary, depending on their specific therapy. Typically, biopsies are done at a single time, or for patients starting a new therapy, biopsies could be performed before starting therapy, during therapy and possibly after completion of therapy. * Tonsil biopsies (patients and volunteers) Volunteers will have one tonsil biopsy. Patients will have no more than six tonsil biopsies, with no more than three in a 10-day period. The biopsy is done by an ear, nose and throat specialist as an outpatient procedure. The tonsils are numbed with a local anesthetic, and one to four pieces of tissue are extracted. * Lymph node biopsies (patients only) Patients will have no more than four lymph node biopsies, performed no more frequently than once a month. The biopsy is done by a surgeon and may require a 2- to 3-day hospital stay. The skin above the lymph nodes is numbed with a local anesthetic, an incision is made and the tissue is removed. Alternatively, a needle biopsy may be done, in which a small amount of lymph tissue is withdrawn through a special needle injected into the site. * Intestinal biopsies (patients and volunteers) Volunteers will have one intestinal biopsy procedure. Patients may have up to six intestinal biopsy procedures, each separated by at least 10 days. This is done by a gastroenterologist as an outpatient procedure. A flexible tube (sigmoidoscope or colonoscope) with a light and special lens at the tip is inserted into the rectum and large bowel. Wire instruments passed through the tube are used to extract small tissue samples. * Bronchoalveolar lavage (BAL; patients and volunteers) Volunteers and patients will undergo bronchoscopy in which a flexible tube (bronchoscope) with a light and special lens at the tip is inserted through the nose or mouth into the lungs, and the lining of the lung is sampled by washing the airways with small amounts of saline. The procedure is performed by a pulmonologist or critical care specialist, usually as an outpatient.