Interleukin 21 (IL-21) has recently been identified as a multifunctional cytokine that induces the proliferation of T cells and B cells and differentiation of natural killer cells. To determine whether IL-21 regulates IL-4–mediated immune responses, we examined the effect of IL-21 on antigen-specific IgE production in mice. We also examined the effect of IL-21 on IL-4–induced IgE production from B cells and antigen-induced T-helper 2 (Th2) cell differentiation. The in vivo injection of IL-21 prevented antigen-specific IgE but not IgG2a production on immunization. IL-21 did not affect Th2 cell differentiation or IL-4 production from CD4+ T cells but directly inhibited IL-4–induced IgE production from B cells at single-cell levels. Moreover, IL-21 inhibited IL-4–induced germ line Cε transcription in B cells without the inhibition of signal transducer and activator of transcription 6 (Stat6) activation. Taken together, these results indicate that IL-21 down-regulates IgE production from IL-4–stimulated B cells through the inhibition of germ line Cε transcription and thus suggest that IL-21 may be useful for the treatment of IgE-dependent allergic diseases.

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Infliximab NRs comprise subtypes with distinct CRP patterns. Failure to suppress the CRP at week 2 identified the majority of patients who were NRs at week 12. CRP suppression at week 12 in the NRs was associated with a late clinical improvement with infliximab treatment (24 weeks), whereas failure to suppress the CRP at week 12 was associated with a good response on switching to etanercept.

To clarify the impact of comorbidities on treatment strategies and outcomes in patients with rheumatoid arthritis (RA) using a large observational RA cohort, the presence of comorbidities was assessed using the Charlson Comorbidity Index (CCI). Changes in medication, disease activity by Disease Activity Score-28 joint count (DAS28) over 6 months, disability assessed by the Japanese version of the Health Assessment Questionnaire (J-HAQ), and quality of life by EuroQOL-5-Dimensions (EQ-5D) over 1 year in patients with high disease activity (DAS28 > 5.1) at baseline were assessed according to age-adjusted CCI (CCI(A)) and categorized into four groups (CCI(A) 0, 1-2, 3-4, and ≥5). Among 5,317 patients, 975 patients (18.3%) had at least one comorbidity listed by CCI. DAS28, J-HAQ, and EQ-5D increased in severity with increased CCI(A) levels. Among patients with high disease activity (n = 267), treatment with methotrexate and/or biologics and improved DAS28 scores, shown by attenuated intensity, were associated with increased CCI(A) levels. J-HAQ improved from 1.29 ± 0.31 to 0.87 ± 0.37 in 1 year in the CCI(A) 0 group. The adjusted difference (standard error) in J-HAQ at 1 year in CCI(A) 1-2, 3-4, and ≥5 groups was worse than J-HAQ in the CCI(A) 0 group by 0.32 (0.09, p < 0.001), 0.45 (0.10, p < 0.001), and 0.45 (0.15, p < 0.01), respectively. The magnitude of improvement of EQ-5D was significantly attenuated with increasing CCI(A) levels. Thus, patients with comorbidities may not experience the same degree of benefit from recent RA treatments compared with patients without comorbidities in daily practice.