Introduction: Although major changes of the immune system have been described in sepsis, it has never been studied whether these may differ in relation to the type of underlying infection or not. This was studied for the first time. Methods: The statuses of the innate and adaptive immune systems were prospectively compared in 505 patients. Whole blood was sampled within less than 24 hours of advent of sepsis; white blood cells were stained with monoclonal antibodies and analyzed though a flow cytometer. Results: Expression of HLA-DR was significantly decreased among patients with severe sepsis/shock due to acute pyelonephritis and intraabdominal infections compared with sepsis. The rate of apoptosis of natural killer (NK) cells differed significantly among patients with severe sepsis/shock due to ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP) compared with sepsis. The rate of apoptosis of NKT cells differed significantly among patients with severe sepsis/shock due to acute pyelonephritis, primary bacteremia and VAP/HAP compared with sepsis. Regarding adaptive immunity, absolute counts of CD4-lymphocytes were significantly decreased among patients with severe sepsis/shock due to community-acquired pneumonia (CAP) and intraabdominal infections compared with sepsis. Absolute counts of B-lymphocytes were significantly decreased among patients with severe sepsis/shock due to CAP compared with sepsis. Conclusions: Major differences of the early statuses of the innate and adaptive immune systems exist between sepsis and severe sepsis/shock in relation to the underlying type of infection. These results may have a major impact on therapeutics.

Purpose of review This review evaluates recent research findings and proposes an up-to-date diagnostic approach for patients with suspected chylothorax. Recent findings Typically, chylothorax is a milky exudate with high triglyceride content (>110 mg/dl). However, milky appearance is not always the case and triglyceride levels can be less than 110 mg/dl, especially in fasting or malnourished patients. Transudative chylothoraces have been reported when cirrhosis, nephrosis or heart failure co-exist. In addition, although the vast majority of the white blood cells in chyle are lymphocytes, chylothoraces can be neutrophilic, especially the postsurgical ones. Summary Chylothorax is the accumulation of chyle into the pleural cavity usually due to thoracic duct leak and should be suspected not only in patients with milky effusions but also in the presence of certain co-morbidities or history of chest/neck trauma. Fluid triglycerides more than 110 mg/dl or less than 50 mg/dl virtually establish or exclude the diagnosis, respectively; ambiguous cases with values 50–110 mg/dl require lipoprotein analysis for the demonstration of chylomicrons. In fasting or malnourished patients lipoprotein analysis is suggested even with triglycerides less than 50 mg/dl. Typical pleural fluid in chylothorax is a lymphocytic exudate with low lactate dehydrogenase; atypical fluid characteristics (i.e. transudative nature, neutrophil-predominance or high lactate dehydrogenase) may be a sign of additional causes of pleural fluid accumulation.

This article summarizes current data regarding the accuracy of pleural fluid tests assisting the diagnosis of tuberculous pleuritis (TBP). No pleural fluid test reliably rules-in TBP in settings with low TBP prevalence. Interferon-γ) alone or in combination with adenosine deaminase (ADA) is more reliable than ADA for this purpose in nonlow prevalences. ADA can reliably rule-out TBP in prevalences of less than 40% although in higher prevalences the product of interleukin-27 and ADA is the most accurate rule-out test. The definite diagnosis of TBP requires the isolation of Mycobacterium tuberculosis from pleural fluid or biopsies. Because of the low sensitivity of pleural fluid cultures and the invasiveness of pleural biopsy techniques, the concept of a pleural fluid test that accurately establishes or excludes TBP diagnosis has been proposed. Numerous pleural fluid tests have been evaluated for this purpose with ADA being the most widely accepted one. During the last years, it has been demonstrated that the ability of ADA to rule-in or rule-out TBP is affected by the prevalence of TBP in the setting where the test is used. The complementary use of interferon-γ or interleukin-27 increases the ability of ADA to rule-in or rule-out the disease, respectively.

Background: Interleukin-27 (IL-27) has been proposed to be useful for diagnosing tuberculous pleural effusion (TPE). Adenosine deaminase (ADA) has been long used for the same purpose. The aim of this study was to compare the performance of IL-27, ADA, and their product (IL-27•ADA) in the diagnosis of TPE. Methods: Pleural fluid samples from patients with exudative pleural effusions were assessed for IL-27 and ADA levels. Receiver operating characteristic (ROC) curves were constructed to compare the overall diagnostic accuracy of IL-27, ADA, and IL-27•ADA. Curves of false-positive (FPR) and false-negative (FNR) rates as a function of TPE prevalence were also constructed, and mean rates of false results in low (1–10%), intermediate (11–40%), and high (41–70%) prevalences were estimated to evaluate the ability of the three markers in ruling in or ruling out TPE. Results: We studied 121 exudates. IL-27 and ADA were higher in TPEs compared with non-TPEs and they presented similar accuracies for the diagnosis of TPE. The product of IL-27 and ADA (IL-27•ADA) was more accurate than ADA for the same purpose. IL-27 and IL-27•ADA presented the lowest overall FPR and FNR, respectively. The FPR of IL-27, ADA and IL-27•ADA was > 9%, even in high prevalence settings. Although their FNR was < 2% in low prevalence settings, only IL-27•ADA exhibited sufficiently low FNR (< 1%) in intermediate and high prevalences. Conclusions: ADA, IL-27, and IL-27•ADA cannot reliably ‘rule in’ TPE in any prevalence setting. TPE can be ‘ruled out’ by each of the biomarkers in low prevalence settings. In intermediate and high prevalence settings, IL-27•ADA is a reliable ‘rule out’ test in the diagnostic approach to TPEs.