Measurement of interleukin-6 in bronchoalveolar lavage fluid by radioimmunoassay: differences between patients with interstitial lung disease and control subjects

Abstract

SUMMARY Bronchoalveolar lavage fluid (BALF) from subjects with a variety of interstitial lung diseases (active sarcoidosis, pigeon breeders' disease (PBD), asymptomatic pigeon breeders, patients with idiopathic pulmonary fibrosis) and from control subjects were assayed for interleukin‐6 (IL‐6) using a novel radioimmunoassay system. IL‐6 was detectable in BALF from all groups, with disease groups showing significantly increased IL‐6 levels compared with controls (P < 0.01 in all cases). When these results were standardized, using urea to compensate for dilution effects in the BALF, only the asymptomatic pigeon breeders had significantly higher IL‐6 levels than the controls (P < 0.025), with all other groups showing no difference. When albumin was used for standardization, both the PBD group (P < 0.001) and the sarcoidosis patients (P < 0.01) had considerably lower levels of IL‐6 than the control subjects. Using either albumin or urea for standardization, the PBD patients had significantly lower levels of IL‐6 than do their asymptomatic counterparts (P < 0.001 in both cases). This is contrasted by the finding of greatly elevated levels of IgG in the BALF of the PBD patients compared with asymptomatics (P < 0.001). There was, however, no relation between IL‐6 and IgG in any patient group, although the PBD patients had the lowest IL‐6 and highest IgG as a group. These findings may suggest a mechanism by which asymptomatic subjects remain free from clinical complaints.

Evaluation of soluble IL-6 receptor concentration in serum and epithelial lining fluid from patients with interstitial lung diseases

“…The present study showed significantly elevated sIL-6R levels in serum, BALF and ELF from patients with interstitial lung diseases. This finding is consistent with the implication that the ligand of the receptor, IL-6, plays a role in the pathogenesis of interstitial lung diseases [18]. Since sIL-6R is only generated in culture supernatants of constitutively IL-6R-bearing cells [15], and T lymphocytes and macrophages are able to express IL-6R, sIL-6R would be produced by such inflammatory cells in patients with sarcoidosis and IP.…”

Effects of a leukotriene B4 receptor antagonist on bleomycin-induced pulmonary fibrosis

“…IL-6 also exhibits a negative feedback on the process of fibrosis. In fact, the IL-6 level of BALF is greatly increased in patients with IPF and in the bleomycin-induced model of pulmonary fibrosis [27]. High IL-6 levels are correlated with alveolar hypercellularity and neutrophil counts in IPF [28].…”

“…However, compared with these cytokines, the IL-6 level in BALF was extremely elevated on day 7 in our bleomycininduced mouse model, and ONO-4057 clearly reduced IL-6. Several studies have demonstrated that IL-6 has both proinflammatory and anti-inflammatory properties [27]. IL-6 also exhibits a negative feedback on the process of fibrosis.…”

Inflammation, Allergy and Asthma, Complex Immune Origin Diseases: Mechanisms and Therapeutic Agents

“…Alternatively, cytokines can be defined as group of cell derived polypeptides, which orchestrate the inflammatory events like cellular infiltration, the state of cellular activation, and the systemic responses to inflammation. Increased concentrations of cytokines in synovial fluids (arthritis) [36], in cerebrospinal fluid (infection or inflammatory disease) [37] or trauma [38], in follicular fluid (ovulation disturbances) [39] and bronchiolar fluid (lungs disorder) [40]. Cytokines, IL-1, TNF-, IL-6, IL-11, IL-8 along with chemokines (G-CSF, and GM-CSF) play a major role in inflammatory reactions (see Table 1).…”