Detection and characterization of subvisible aggregates of monoclonal lgG in serum

To detect and characterize the aggregation of therapeutic monoclonal antibodies in undiluted biological fluids. Fluorescently labeled subvisible IgG aggregates formed by applying either heat stress or by pH-shift were investigated immediately after addition to human serum, and after 24 h. Unstressed and stressed IgG formulations were analyzed by fluorescence single particle tracking, confocal laser scanning microscopy and flow cytometry. Unstressed formulations remained free from subvisible aggregates in serum, whereas heat-stressed and pH-shift stressed formulations showed dissimilar aggregation behaviors. The aggregation profile of the heat-stressed formulation diluted in serum remained practically the same as the one diluted in buffer, even after the 24 h incubation period. The pH-shift stressed formulation had strikingly smaller and more numerous subvisible aggregates immediately after dilution in serum compared to buffer. These aggregates became noticeably larger in both diluents after 24 h, but in serum they appeared to be formed by other types of constituents than the labeled protein itself. These results show that subvisible therapeutic protein aggregates may undergo changes in number, type and size distribution upon contact with human serum. This emphasizes the importance of analytical strategies for monitoring aggregation in undiluted biological fluids

Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function

<p>Abstract</p> <p>Background</p> <p>Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFα and IL-1β, rather than as regulatory cytokine.</p> <p>Objective</p> <p>To investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease.</p> <p>Methods</p> <p>Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects.</p> <p>Results</p> <p>The levels of the proinflammatory biomarkers TNFα and IL-1β were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p < 0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p < 0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (r_S= 0.53, p < 0.05).</p> <p>Conclusions</p> <p>In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.</p