Hydrolytic enzyme of the alveolar macrophage in diffuse pulmonary interstitial disease.

Hydrolytic enzymes [acid phosphatase, beta-glucuronidase, beta-D-N-acetyl glucosaminidase (beta-D-NAGA), lysozyme and angiotensin-converting enzyme (ACE)] are the major constituents of alveolar macrophages (AM). These enzymes play a crucial role in the pathogenesis of interstitial lung diseases. Cell-associated activity of several enzymes in alveolar macrophages obtained from control subjects (n = 5) and patients suffering five representative types of interstitial pulmonary diseases [sarcoidosis (n = 10), extrinsic allergic alveolitis (n = 5), idiopathic pulmonary fibrosis (n = 5), neoplastic infiltration of the lung (n = 5) and Pneumocystis carinii pneumonia (n = 5)] were evaluated. Cells were obtained by bronchoalveolar lavage and isolated by Ficoll-Hypaque gradient. Enzymatic activity was assessed by standardized tests. Bronchoalveolar lavage (BAL) lymphocyte counts were significantly elevated in the patients with active sarcoidosis (median: 57%), allergic extrinsic alveolitis (median: 51%) and neoplastic infiltration (median: 31%) as compared with the other groups, whereas BAL neutrophil and eosinophil counts were significantly elevated in the patients with idiopathic pulmonary fibrosis (neutrophil median: 29%; eosinophil median: 3%). The highest alveolar macrophage enzymatic activities were obtained in the active sarcoidosis group (median ACE: 23.38 microKat 10(-6) AM; median lysozyme: 8.64 nKat 10(-6) AM; median beta-glucuronidase: 324.22 U 10(-6) AM; median acid phosphatase: 0.78 nKat 10(-6) AM; median beta-D-NAGA: 1.85 nKat 10(-6) AM) which was significantly greater than in the control group (median ACE: 6.69 microKat 10(-6) AM; median lysozyme: 1.95 nKat 10(-6) AM; median beta-glucuronidase: 39.88 U 10(-6) AM; median acid phosphatase: 0.38 nKat 10(-6) AM; median beta-D-NAGA: 0.44 nKat 10(-6) AM). However, intracellular lysosomal enzymatic activities of alveolar macrophages from patients with allergic extrinsic alveolitis, a disease in which the degree of alveolar macrophage activation is maximal, were similar to those of the control group. These findings demonstrated a different pattern of expression of alveolar macrophage's hydrolytic enzymes in lymphocytic diffuse pulmonary interstitial disease. In sarcoidotic patients, hydrolytic enzymes were increased whereas in allergic extrinsic alveolitis, hydrolytic enzyme activities were similar to control groups. Indirect data suggest that the release of lysosomal enzymes by alveolar macrophages during allergic extrinsic alveolitis may be a factor involved in the pulmonary lesions appearing in this disease.

Possible role of bovine immunodeficiency virus in bovine paraplegic syndrome: evidence from immunochemical, virological and seroprevalence studies.

Bovine paraplegic syndrome (BPS) is a debilitating cattle disease of unknown origin that is characterized by leukocytosis, lymphocytopenia and monocytopenia. The major clinical signs are difficulties in locomotion affecting hind limbs, hypoalgesia in the hind quarters, posterior paralysis and death within 72 to 96 hours after recumbency. To investigate the aetiological basis of BPS, we examined a possible association of the syndrome with infection by bovine immunodeficiency virus (BIV), a lentivirus implicated in immune system dysfunction and central nervous system lesions in cattle. Serum samples (n = 1,278) were collected from both healthy and BPS-prevalent cattle herds in Venezuela, and organ extracts were prepared from euthanized animals (n = 11) suspected of having BPS. Sera were analysed for reactivity to recombinant BIV and bovine leukaemia virus gag precursor proteins by immunoblot procedures. Serum reactivity to BIV ranged from 12 to 66% between groups of BPS prevalent herds. The percentage of samples reactive to BLV antigen was much lower (2 to 17%). Rabbits inoculated with extracts from BPS-afflicted animals exhibited an anamnestic immune response to BIV antigens as well as the presence of BIV gag antigens in their tissues. We present evidence for a possible association between BPS disease and a viral agent related to BIV. The role of BIV, in combination with malnutrition, in BPS is discussed.

Role of lysosomal enzymes released by alveolar macrophages in the pathogenesis of the acute phase of hypersensitivity pneumonitis.

Hydrolytic enzymes are the major constituents of alveolar macrophages (AM) and have been shown to be involved in many aspects of the inflammatory pulmonary response. The aim of this study was to evaluate the role of lysosomal enzymes in the acute phase of hypersensitivity pneumonitis (HPs). An experimental study on AM lysosomal enzymes of an HP-guinea-pig model was performed. The results obtained both in vivo and in vitro suggest that intracellular enzymatic activity decrease is, at least partly, due to release of lysosomal enzymes into the medium. A positive but slight correlation was found between extracellular lysosomal activity and four parameters of lung lesion (lung index, bronchoalveolar fluid total (BALF) protein concentration, BALF LDH and BALF alkaline phosphatase activities). All the above findings suggest that the AM release of lysosomal enzymes during HP is a factor involved, although possibly not the only one, in the pulmonary lesions appearing in this disease.