Addition of Mac-1+ cells from the macrophage-rich fraction to the lymphocyte-rich fraction was essential for production of IL-4 and total IgE Abs in the lymphocytes (Figs. 5–7). Therefore, it is unlikely that cultured monocytes (8) or macrophages (present
study) internalize and degrade allergen to present peptides from internal proteins to T cells, implying antigen-nonspecific activation of T cells by macrophages. In conclusion: (i) the submandibular lymph nodes are the main organ responsive to i.n. injected cedar pollen; (ii) bulk cells in the submandibular lymph nodes from mice that have been treated i.n. once with allergen alone or with a mixture of Decitabine allergen and complete Freund’s adjuvant mainly produce IgE or IgG, respectively; and (iii) macrophages in the submandibular lymph nodes are essential for IL-4, IgE or IgG production by lymphocytes and are involved in class switching of Ig in B lymphocytes by controlling the amounts of IL-4 released from CD3+ T lymphocytes. We thank T. Ueno for his technical assistance. This work was supported in part by the Mori and Magari Memorial Research Funds of Osaka Medical College, and by a grant-in-aid for young scientists (B) (Grant No. 21791652) from the Ministry of Education, Science, and Culture, Japan. The authors have no financial conflicts of interest. “
“IFN-α and IL-4 induce Th1 and Th2 responses, respectively, and
often display antagonistic actions against each Rapamycin other. To elucidate 3-mercaptopyruvate sulfurtransferase the molecular mechanism of counter-regulation, we have investigated the signal interception by IFN-α and IL-4, employing a human B-cell line Ramos, sensitive to both cytokines. In these cells, IFN-α effectively inhibited IL-4-induced Fc epsilon receptor II (CD23) expression,
whereas IL-4 suppressed IFN-α-mediated IRF7 expression. The counter-regulatory action by IL-4 and IFN-α proceeded with a delayed kinetics requiring 4 h. Notably, IFN-α did not affect the IL-4-induced tyrosine phosphorylation of STAT6, but induced a time-dependent cytoplasmic accumulation of phosphotyrosine(pY)-STAT6 and a corresponding decrease in nuclear pY-STAT6. By confocal analysis and co-immunoprecipitation assays, we demonstrated the colocalization and molecular interaction of IL-4-induced pY-STAT6 with IFN-α-induced pY-STAT2:p48 in the cytosol. In addition, the over-expression of STAT2 or STAT6 induced the concomitant cytosolic accumulation of pY-STAT6 or pY-STAT2, leading to the suppression of IL-4-induced CD23 or IFN-α-induced IRF7 gene expression, respectively. Our data suggest that the signals ensued by IFN-α and IL-4 induce cytoplasmic sequestration of IL-4-activated STAT6 and IFN-α-activated STAT2:p48 in B cells through the formation of pY-STAT6:pY-STAT2:p48 complex, which provides a novel mechanism by which IFN-α and IL-4 cross-regulate their signaling into the nucleus.