Lack of IL-21 signal attenuates graft-versus-leukemia effect in the absence of CD8 T-cells.

Previously, we have shown that IL-21R(-/-) splenocytes ameliorate GVHD as compared with wild-type splenocytes. Here, we investigated whether or not IL-21R(-/-) splenocytes diminish the graft-versus-leukemia (GVL) effect. Surprisingly, IL-21R(-/-) splenocytes efficiently eliminate leukemic cells as well as wild-type splenocytes, suggesting the retention of GVL effects in the absence of IL-21 signaling. To compare the GVL effect between IL-21R(-/-) and wild-type cells, we titrated the number of splenocytes required for the elimination of leukemic cells and found that the threshold of GVL effect was obtained between 5 × 10(5) and 5 × 10(6) with both types of splenocytes. Cotransplantation with CD8-depleted splenocytes but not with purified CD8 T-cells resulted in a significant reduction in anti-leukemic effect of IL-21R(-/-) cells compared with wild-type cells, suggesting that the lack of IL-21 signaling primarily impairs CD4 T-cell rather than CD8 T-cell function and the comparable GVL effect with IL-21R(-/-) bulk splenocytes results from cooperative compensation by CD8 T-cells.

IL-21 is critical for GVHD in a mouse model.

Immunological effects of IL-21 on T, B and natural killer (NK) cells have been reported, but the role of IL-21 in GVHD remains obscure. Here, we demonstrate that morbidity and mortality of GVHD was significantly reduced after BMT with splenocytes from IL-21R(-/-) mice compared with those from wild type mice. To further confirm our observation, we generated a decoy receptor for IL-21. GVHD was again less severe in mice receiving BM cells transduced with the IL-21 decoy receptor than control mice These results suggest that IL-21 critically regulates GVHD, and that blockade of the IL-21 signal may represent a novel strategy for the prophylaxis for GVHD.

Interferon-gamma and NF-kappaB mediate nitric oxide production by mesenchymal stromal cells.

Mesenchymal stromal cells (MSCs) have been shown to have an immunosuppressive effect. Previously, we demonstrated that nitric oxide (NO) is one of the immunomodulatory mediators of MSCs. We herein show that primary mouse bone marrow MSCs and three cell lines that mimic MSCs suppress both differentiation and proliferation in Th1 condition, whereas the suppression in Th2 condition is mild. NO production is inversely correlated with T cell proliferation in Th1 and Th2 conditions. NO is highly induced in Th1 and minimally induced in Th2. Moreover, an inhibitor of NO synthase restores both proliferation and interferon-gamma (IFN-gamma) production in Th1 condition. Furthermore, an anti-IFN-gamma antibody strongly inhibits NO production and an inhibitor of NF-kappaB reduces the level of induction of inducible NO synthase (iNOS) in MSCs. Taken together, our results suggest that NO plays a significant role in the modification of Th1 and Th2 differentiation by MSCs, and that both IFN-gamma and NF-kappaB are critical for NO production by MSCs.

Serum C-reactive protein in the differential diagnosis of childhood meningitis.

BACKGROUND: Although determination of serum C-reactive protein (CRP) is considered one of the most useful tests for differentiating between bacterial and aseptic meningitis, its diagnostic accuracy in comparison with other laboratory parameters is yet to be further evaluated. METHODS: A total of 192 pediatric cases, aged between 2 months and 14 years, comprising patients with bacterial meningitis (n = 66) and aseptic meningitis (n = 126), were retrospectively analyzed on the basis of data from the initial examination. The area under the best fit binormal curve of the receiver operating characteristics (Az) for CRP was determined and compared with that for several other analytic parameters, including white blood cell count and erythrocyte sedimentation rate of peripheral blood, standard cerebrospinal fluid analysis variables and the combination test (probability of acute bacterial meningitis (pABM)) derived from Hoen's model. RESULTS: Compared with each of the other variables, the Az for serum CRP (0.97 +/- 0.02) was found to be significantly greater (P < 0.01) for all except pABM (0.99 +/- 0.01; P > 0.05). False-negative cases among the CRP test results were found to have been examined too early. CONCLUSIONS: The diagnostic accuracy of a single CRP determination was found to be equivalent to that of the most effective combination test. Patients with meningitis in whom serum CRP values are determined at least 12 h after the onset of fever and are < 2 mg/dL are far less likely to have bacterial meningitis.