Interleukin-6 is a cytokine that plays an important role in both innate and adaptive immunity. Its primary function in adaptive immunity is stimulation of the growth of B cells (1). In a recent article by Chu et al. (2), the authors measured IL-6 production in B cells derived from four different genotypes under five different conditions as a part of their research to examine the functional overlapping of two proteins, A20 and CYLD. In this letter, we propose a hypothesis on the mechanism of the production of IL-6 in B cells.
We grouped the 20 different measurements of IL-6 shown in the bottom panel of Fig. 4B of the article into five groups based on proximity of values (Fig. 1A). We found that the relationship between the quantum level (x) and the IL-6 amount (y) is described by a linear equation, y = ax + b (Fig. 1B). The slope a corresponds to the quantized amount of IL-6. This means that IL-6 production in B cells may be quantized with constant spacing between each level. This type of quantized behavior has been previously observed in the release of neurotransmitters from presynaptic cells (3).
(A) The amount of IL-6 produced in B cells in ascending order. They are combined into five groups. When a group contains multiple elements, then the average value is taken as the representative value of the group. Each group is treated as a quantum level. (B) Quantized production of IL-6 as a function of quantum level. The relationship is fitted to a linear equation, y = ax + b, where a = 417 ± 17 and b = 860 ± 58, respectively (R2: 0.9948). The IL-6 amount is expressed by mean fluorescence intensity (MFI). Fitting was conducted using SigmaPlot (version 11, Systat Software, San Jose, CA).
To test our hypothesis, we would like to suggest that further experiments be conducted to verify if A20/CYLD-deficient and A20-deficient B cells produce IL-6 in a quantized pattern responding to combined stimuli (such as LPS and CpG).
- Copyright © 2013 by The American Association of Immunologists, Inc.
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