Mixed IgG Fc immune complexes exhibit blended binding profiles and refine FcR affinity estimates.

Immunoglobulin G (IgG) antibodies coordinate immune effector responses by interacting with effector cells via fragment crystallizable γ (Fcγ) receptors. The IgG Fc domain directs effector responses through subclass and glycosylation variation. Although each Fc variant has been extensively characterized in isolation, during immune responses, IgG is almost always produced in Fc mixtures. How this influences effector responses has not been examined. Here, we measure Fcγ receptor binding to mixed Fc immune complexes. Binding of these mixtures falls along a continuum between pure cases and quantitatively matches a mechanistic model, except for several low-affinity interactions mostly involving IgG2. We find that the binding model provides refined estimates of their affinities. Finally, we demonstrate that the model predicts effector cell-elicited platelet depletion in humanized mice. Contrary to previous views, IgG2 exhibits appreciable binding through avidity, though it is insufficient to induce effector responses. Overall, this work demonstrates a quantitative framework for modeling mixed IgG Fc-effector cell regulation.

Mixed IgG Fc immune complexes exhibit blended binding profiles and refine FcR affinity estimates.

Immunoglobulin (Ig)G antibodies coordinate immune effector responses by selectively binding to target antigens and then interacting with various effector cells via the Fcγ receptors. The Fc domain of IgG can promote or inhibit distinct effector responses across several different immune cell types through variation based on subclass and Fc domain glycosylation. Extensive characterization of these interactions has revealed how the inclusion of certain Fc subclasses or glycans results in distinct immune responses. During an immune response, however, IgG is produced with mixtures of Fc domain properties, so antigen-IgG immune complexes are likely to almost always be comprised of a combination of Fc forms. Whether and how this mixed composition influences immune effector responses has not been examined. Here, we measured Fcγ receptor binding to immune complexes of mixed Fc domain composition. We found that the binding properties of the mixed-composition immune complexes fell along a continuum between those of the corresponding pure cases. Binding quantitatively matched a mechanistic binding model, except for several low-affinity interactions mostly involving IgG2. We found that the affinities of these interactions are different than previously reported, and that the binding model could be used to provide refined estimates of these affinities. Finally, we demonstrated that the binding model can predict effector-cell elicited platelet depletion in humanized mice, with the model inferring the relevant effector cell populations. Contrary to the previous view in which IgG2 poorly engages with effector populations, we observe appreciable binding through avidity, but insufficient amounts to observe immune effector responses. Overall, this work demonstrates a quantitative framework for reasoning about effector response regulation arising from IgG of mixed Fc composition. Summary points: The binding behavior of mixed Fc immune complexes is a blend of the binding properties for each constituent IgG species.An equilibrium, multivalent binding model can be generalized to incorporate immune complexes of mixed Fc composition.Particularly for low-affinity IgG-Fcγ receptor interactions, immune complexes provide better estimates of affinities.The FcγR binding model predicts effector-elicited cell clearance in humanized mice.

Effectiveness of pranayama on cancer-related fatigue in breast cancer patients undergoing radiation therapy: A randomized controlled trial.

CONTEXT: Incidence of breast cancer is very high among women around the world. Breast cancer patients experience cancer-related fatigue at some points during the treatment for breast cancer. Since cancer-related fatigue is of multifactorial origin, there are no evidence-based treatment strategies for fatigue. This study tested the effectiveness of certain pranayama techniques in reducing cancer-related fatigue among breast cancer patients undergoing radiation therapy. AIMS: The objective of this study was to determine the effectiveness of pranayama on cancer-related fatigue among breast cancer patients undergoing radiation therapy as measured by cancer fatigue scale. SETTINGS AND DESIGN: Shirdi Sai Baba Cancer Hospital and Research Center, Kasturba Hospital Manipal. MATERIALS AND METHODS: Study was a randomized controlled trial done among breast cancer patients receiving radiation therapy. STATISTICAL ANALYSIS USED: Demographic characteristics of the participants are presented as frequency and percentage. Comparison of means of cancer-related fatigue between the two groups is done by Mann-Whitney U-test and comparison of pre- and pos t-test means of cancer-related fatigue among the experimental group is done by Wilcoxon sign rank test. RESULTS: There was a significant difference between the two groups with regard to the scores of cancer-related fatigue. The experimental group of patients who performed pranayama along with radiation therapy experienced less fatigue. CONCLUSIONS: Pranayama can be used as a supportive therapy for breast cancer patients undergoing radiation therapy.