Intrapulmonary activation of leukocytes and release of cellular mediators and enzymes are involved in the pathophysiology of the adult respiratory distress syndrome (ARDS). To investigate a possible role of local cytokines, we measured bronchoalveolar fluid (BALF) and plasma levels of tumor necrosis factor alpha (TNF-alpha) and its soluble inhibitors (sTNF-RI + RII), interleukin-1 beta (IL-1 beta), interferon-alpha (IFN-alpha), and granulocyte elastase in 14 patients at risk for ARDS and in 35 patients developing ARDS after trauma, sepsis, or shock. During clinical development of severe ARDS, BALF cytokines increased markedly: TNF-alpha from 116 +/- 36 to 10,731 +/- 5,048 pg/ml (mean +/- SEM), p = 0.001; sTNF-RI + RII from 3.7 +/- 1.4 to 24.6 +/- 2.6 ng/ml, p less than 0.05; and IL-1 beta from 7,746 +/- 5,551 to 42,255 +/- 19,176 pg/ml, p = 0.01. Plasma cytokines were not increased in most patients, nor were they correlated with the development or severity of ARDS. BALF elastase was higher in patients developing ARDS than in those at risk but not going into pulmonary failure (0.97 +/- 0.26 versus 0.28 +/- 0.13 U/ml, p = 0.026), and the highest values were observed in the early stages of severe ARDS (1.85 +/- 0.39 U/ml). BALF elastase levels correlated with IFN-alpha (r = 0.72, p less than 0.001). In conclusion, local release of TNF-alpha and IL-1 beta, possibly by pulmonary macrophages or other cells, and/or accumulation in the lung is associated with the development of ARDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum concentrations of immunoreactive tumor necrosis factor/cachectin (TNF), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN gamma), and interferon-alpha (IFN alpha) were prospectively measured in 70 patients with septic shock to determine their evolution and prognostic values. In a univariate analysis, levels of TNF (P = .002) and IL-1 beta (P = .05) were associated with the patient's outcome, but not IFN alpha (P = .15) and IFN gamma (P = .26). In contrast, in a stepwise logistic regression analysis, the severity of the underlying disease (P = .01), the age of the patient (P = .02), the documentation of infection (nonbacteremic infections vs. bacteremias, P = .03), the urine output (P = .04), and the arterial pH (P = .05) contributed more significantly to prediction of patient outcome than the serum levels of TNF (P = .07). After 10 days, the median concentration of TNF was undetectable (less than 100 pg/ml) in the survivors, whereas it remained elevated (305 pg/ml, P = .002) in the nonsurvivors. Thus, in patients with septic shock due to various gram-negative bacteria, other parameters than the absolute serum concentration of immunoreactive TNF contributed significantly to the prediction of outcome.

Extracellular vesicles (EVs) are blebs of either plasma membrane or intracellular membranes carrying a cargo of proteins, nucleic acids, and lipids. EVs are produced by eukaryotic cells both under physiological and pathological conditions. Genetic and environmental factors (diet, stress, etc.) affecting EV cargo, regulating EV release, and consequences on immunity will be covered. EVs are found in virtually all body fluids such as plasma, saliva, amniotic fluid, and breast milk, suggesting key roles in immune development and function at different life stages from in utero to aging. These will be reviewed here. Under pathological conditions, plasma EV levels are increased and exacerbate immune activation and inflammatory reaction. Sources of EV, cells targeted, and consequences on immune function and disease development will be discussed. Both pathogenic and commensal bacteria release EV, which are classified as outer membrane vesicles when released by Gram-negative bacteria or as membrane vesicles when released by Gram-positive bacteria. Bacteria derived EVs can affect host immunity with pathogenic bacteria derived EVs having pro-inflammatory effects of host immune cells while probiotic derived EVs mostly shape the immune response towards tolerance.

To investigate the relation of tumor necrosis factor-alpha (TNF alpha) to Plasmodium falciparum infection, plasma TNF alpha concentrations were measured in Zairian children with severe malaria, mild malaria, or other illnesses. The initial geometric mean plasma concentration of TNF alpha among 61 children with P. falciparum infection, (71 pg/ml) was higher than the level in 26 severely ill, aparasitemic children (10 pg/ml; P less than .001). Among 29 parasitemic children, initial geometric mean TNF alpha levels decreased from 77 to 5 pg/ml (P less than .001) at day 7. TNF alpha levels increased with parasite density and were associated with hyperparasitemia, severe anemia, hypoglycemia, and young age but not with cerebral malaria or fatal outcome. However, TNF alpha levels were elevated equally in children with cerebral malaria and with other signs of severe malaria. With multiple linear regression, TNF alpha levels were elevated independently in children with hyperparasitemia (P = .001) and severe anemia (P = .04). In this study, high TNF alpha levels were associated with several manifestations of severe malaria and were not specific to cerebral malaria.