ABSTRACT
CD44 glycoproteins are present on the surfaces of many hematopoietic cells and in some cases can bind hyaluronan, a major component of the extracellular matrix. In the present study, we have found that newly explanted human peripheral blood monocytes (PBMs) exhibit a major CD44 band of 85 kDa, whereas autologous alveolar macrophages (AM phi) express multiple isoforms ranging from 85 to 200 kDa. Within 4 h in culture, PBMs began expressing new CD44 isoforms of 120, 150, and 180 kDa. Newly explanted AM phi specifically bound [3H]hyaluronan (135 cpm/microgram protein), but newly explanted PBMs did not. However, in vitro cultured PBM progressively acquired the ability to bind [3H]hyaluronan and exhibited specific binding of hyaluronan similar to that of AM phi (113 cpm/microgram protein) after 4 days in culture. In both case, the binding of [3H]hyaluronan was specifically inhibited by the addition of monoclonal antibody directed against CD44. AM phi readily degraded [3H]hyaluronan and reached a plateau after 4 days in culture (115 cpm/microgram protein). Newly explanted PBM exhibit no hyaluronan degradation and only a small degradative activity after 4 days in culture (6 to 11 cpm/microgram protein). Thus, CD44 expression and function appear to change as PBM mature in vitro resembling more that found in AM phi.
Subject(s)
Carrier Proteins/physiology , Macrophages, Alveolar/chemistry , Monocytes/chemistry , Receptors, Cell Surface/physiology , Receptors, Lymphocyte Homing/physiology , Adult , Carrier Proteins/chemistry , Carrier Proteins/metabolism , Cells, Cultured , Female , Humans , Hyaluronan Receptors , Hyaluronic Acid/metabolism , Lymphocytes/metabolism , Male , Molecular Weight , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/metabolism , Receptors, Lymphocyte Homing/chemistry , Receptors, Lymphocyte Homing/metabolismABSTRACT
Since first described in 1984, nontraumatic pneumothoraces in patients with AIDS has become more common. When compared with spontaneous pneumothorax in the general population, pneumothoraces in patients with AIDS are often complicated by prolonged air leaks as well as higher recurrence rates. Chemical pleurodesis has an important role in the management of these complications. The most experience with chemical pleurodesis uses tetracycline hydrochloride as the sclerosing agent; however, this agent is no longer available. Doxycycline has been used in pleurodesis of malignant effusions, but its use in managing pneumothoraces is limited. We present five patients who have AIDS with a total of seven pneumothoraces. Each patient experienced a persistent air leak. Six of the pneumothoraces were managed successfully with doxycycline. Although the follow-up period was limited, there were no recurrences noted and the only side effect seen was chest pain in four which was easily controlled with narcotics. Doxycycline sclerotherapy can be used effectively for pleurodesis in the management of nontraumatic pneumothorax in the patient with AIDS.
