| Autor: |
Ning Gao, Paula Jennings, Dorothy Yuan |
| Předmět: |
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| Zdroj: |
International Immunology; May2008, Vol. 20 Issue 5, p645-645, 1p |
| Abstrakt: |
Upon interaction with resting B lymphocytes, IL-2-propagated NK cells can initiate the process of Ig constant region switch recombination (CSR) by inducing germ line transcripts for γ2a (Iγ2a) as well as increased levels of mRNA for activation-induced cytidine deaminase enzyme. Whereas both these processes are necessary for CSR, they are not sufficient because the cells do not proceed to the expression of mature mRNA for γ2a (VDJCγ2a). In addition, NK cells can also upregulate mRNA for the T-box transcription factor (T-bet) in B cells without being able to induce further differentiation. Using transgenic B cells with B cell receptor specificity for nitrophenol (NP), we have now shown that NP–Ficoll-stimulated B cells can be induced by NK cells to express IgG2a as well as IgG1 presumably due to the completion of the process of switch recombination. The inductive ability of NK cells does not require IFN-γ but does require signals transmitted via CD48 by direct cell contact. In addition, NP–Ficoll on its own can induce proliferation of antigen-specific B cells as well as germ line transcripts of γ1; however, expression of VDJCγ1 mRNA also requires NK cell interaction with B lymphocytes. Therefore, in the presence of antigen, NK cells can provide a necessary signal that substitutes for cytokines in the induction of IgG2a as well as IgG1 expression. This in vitro analysis provides a mechanistic basis for understanding the documented NK cell effects on T-independent B cell responses in vivo. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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