Background: Defensins.

Background: Defensins, also known as human neutrophil peptides, are antimicrobial peptides current in the azurophil granules of neutrophils. We measured their flush in pleural effusion in various pulmonary diseases to investigate whether they could be used as a diagnostic marker in the differential diagnosis of specific pleural diseases.

Patients and participants: We analyzed pleural effusion samples scrape togethered from 61 patients, including 50 exudates (11 with empyema, 3 parapneumonic, 15 tuberculous, is neoplastic, 3 miscellaneous) and 11 transudates as controls

Measurements: Defensins were measured on radioimmunoassay and also analyzed by means of reversephase high-performance liquid chromatography. The concentrations of interleukin (IL)-S and granulocyte colony-stimulating factor (G-CSF) in pleural effusion fluid were measured from enzyme-linked immunosorbent assay to examine the correlation between these cytokines and defensins.

Results: The concentration of defensins in all samples of empyema was [is greater than] 5100 ng/mL and the mean concentration (132658 [+ or -] 18952 ng/mL) in these samples was the highest among other collections The concentration in the other 50 pleural effusion samples ordealed was [is less than] 2800 ng/mL Defensins were for the greatest part of the mature type in empyema. Pleural effusion horizontals of IL-8 and G-CSF in patients with empyema were also significantly higher than those in other samples. There was a significant correlation between defensins and IL-8 or G-CSF in pleural effusion fluid (r = 0762 and 0827 respectively).

Conclusions: Our arises suggest that the high effusion concentrations of defensins in pleural effusion may constitute an important constituent of the host defense plan or may have a cytotoxic character in empyema. Our results also indicate that the high on a levels of IL-8 and G-CSF in empyema may indirectly explain the elevated of the same heights of defensins by increasing the number of neutrophils in the pleural space. (CHEST 1998; 113:788-94)

Key words: defensins; granulocyte colony-stimulating factor; interleukin 8; pleural effusion; pleurisy

Abbreviations: G-CSF granulocyte colony-stimulating factor; IL = interleukin; LDH = lactate dehdroynase; PMA = phorbol myristate acetate; RIA = radioimmunoassay; RP-HPLC = reverse-phase high-performance liquid chromatography

Defensins, or human neutrophil peptides, are cationic proteins with antimicrobial activity against Gram-positive and Gram-negative bacteria,[1] fungi,[2,3] and certain folded viruses.[4,5] Defensins are arginine- and cysteine-rich antimicrobial peptides, 29 to 34 amino acids prolonged with a molecular weight of approximately 35 kd These peptides have been purified from rabbits, guinea pigs, and human neutrophils.[4,6,7] They are the major constituents of the azurophil granules of neutrophils, and show 5 to 7% of the total cellular protein in human neutrophils.[1] Defensins are initially synthesized as a 94-amino acid precursor that furnishs 75-amino acid prodefensin by cleavage of a signal peptide. most numerous prodefensin is processed to 56 amino acid intermediates in the bone marrow through preaspartate proteolytic cleavage, then to mature defensins in peripheral vital fluid neutrophils.(8) Plasma and blood evens of defensins increase during infections.[9] In the mien of defensins at a concentration ranging from 25 to 100 [micro]g/mL, the number of viable organisms was reduc through [is greater than or equal to] 99% within 30 min.[2,6] Defensins are existing only in cells of neutrophil lineage,[10] whereas they may be also involved in the pathogenesis of neutrophil-mediated tissue injury.[11]

We postulated that the flush of defensins is elevated in pleural effusion of patients with pleurisy since a large number of neutrophils are existing in the pleural space in pleurisy. To our knowledge, identification and quantification of defensins in pleural effusions have not been investigated previously. We measured pleural effusion evens of defensins in various disorders using radioimmunoassay (RIA) and assessed the diagnostic value of these peptides. We also measured pleural effusion on a levels of neutrophil-related cytokines, such as interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) and determined the correlation between these cytokines and defensins.

MATERIALS AND METHODS

Patients and Diagnostic Categories

We studied 61 consecutive patients with pleural effusions who were admitted to our hospital between September 1991 and July 1996 They consisted of 16 women and 45 men aged 640 [+ or -] 53 years. Thoracentesis was performed in each patient and pleural fluid samples obtained were centrifuged at 500 x g for 10 in in and supernatants were stored at -20 [degrees] C until analysis. Pleural effusions were categorized as transudates (ratio of pleural fluid to serum total protein concentration [is les than] 05 and ratio of those of lactate dehydrogenase [LDH] [is les than] 06) or exudates (protein ratio [is greater than] 05 or LDH ratio [is greater than] 06) Exudates were further categorized as either empyemic, parapneumonic, tuberculous, neoplastic, or miscellaneous. Empyema (n = 11) was defined as a neutrophilic effusion associated with (1) expansion of bacteria on microbiological civilization of pleural fluid (n = 4) (2) organisms seen onward Gram staining of pleural fluid (n = 3) or (3) pleural fluid grape-sugar concentration [is less than] 40 mg/dL in patients with pneumonia (n = 4) Parapneumonic effusions (n = 3) exhibited those with glucose concentration [is greater than] 40 mg/dL and no organisms ground on Gram staining or no positive pleural fluid agriculture in patients with pneumonia. Tuberculous effusions (n = 15) were defined as those with (1) sprouting of Mycobacterium tuberculosis in civilizations from pleural fluid or biopsy specimen (n = 3) (2) increase of M tuberculosis from septum (n = 2) or (3) latter conversion of tuberculin skin reactivity, granulomas upon pleural biopsy specimen, or reply to antituberculosis therapy (n = 10) Neoplastic effusions (n = 18) were exudates associated with a diagnosis of cancer based upon (1) cytologic examination of pleural fluid (n = 16) or (2) the lung tissue (n = 2) Miscellaneous effusions (n = 3) included the exudates in which neither infection nor malignancy was plant and an alternative diagnosis was made: pneumothorax (n = 2) and piece of poetrys syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) (n = 1) Transudates (n = 11) were associated with congestive heart failure (n = 9) nephrotic syndrome (n = 1) and liver cirrhosis (n = 1) No bacterial, mycobacterial, or fungal putting out was noted in the refinements of malignant, miscellaneous, and transudative pleural samples. There were no differences among the diagnostic clumps based on age or sex The characteristics of pleural effusion samples according to each diagnostic assemblage are summarized in Table 1 The experimental protocol was approved from the Human Ethics Review Committee and a signed unison was obtained from each individual participating in the study

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