Studies on the B cell development and its microenvironment

我们描述了胸腺中的B细胞祖细胞。虽然成熟的胸腺B细胞为sIg^+、B220^+，但胸腺中的CD 43 ^-、B祖细胞为sIg^-、B220^<med>+、CD 43 ^+。当通过PCR扩增来自分选的B细胞祖细胞的DNA时，大多数祖细胞显示重排的IG D-J和V-D-J模式。当从胸腺中纯化B细胞祖细胞并将其胸腺内注射到Ig同种异型不同受体中时，在胸腺中检测到携带供体型Igh 6的B细胞，但在外周中未检测到。由这些祖细胞产生的胸腺B细胞是CD 5 ^+细胞，尽管CD 5分子的表达范围很广。此外，从接种了B细胞祖细胞的胸腺纯化的B细胞能够在CD 40配体加IL-10的影响下分化为抗体形成细胞，并分泌具有供体Igh 6同种异型的IgM。将胸腺前体B细胞静脉注射给scid小鼠后，胸腺前体B细胞可分化为成熟的B细胞，静脉注射后胸腺中检测到的CD 5 ^+ B细胞百分比明显升高。注射组明显高于脾脏和淋巴结组。这些发现表明B细胞的表面表型可能受到微环境的影响。目的：阐明支持胸腺祖细胞B细胞、基质细胞分化的体外条件。在IL-7的存在下，胸腺基质细胞，而不是来自骨髓的基质细胞或胸腺细胞系，可以支持胸腺祖B细胞的分化。

We characterize B cell progenitors in the thymus. Though mature thymic B cells are sIg^+, B220^+, but CD43^-, B cell progenitors in the thymus were found to be sIg^-, B220^<med>, and CD43^+. Most progenitors showed rearranged Ig D-J and V-D-J patterns when DNA from sorted B cell progenitors was amplified by PCR,blotted and probed. When B cell progenitors were purified from the thymus and injected intrathymically into Igh-allotype disparate recipients, B cells bearing donor-type Igh6 were detected in the thymus but not in the periphery. Thymic B cells generated from these progenitors were CD5^+ cells, though there was a broad range of expression of CD5 molecules. Furthermore, B cells purified from thymus that had been inoculated with B cell progenitors were able to differentiate into antibody-forming cells under the influence of CD40 ligand plus IL-10, and secreted IgM with donor Igh6-allotype. When thymic progenitor B cells were intravenously injected into scid mice, thymic progenitor B cells can differentiate to mature B cells, and the percentage of CD5^+ B cells detected in the thymus after iv. injection was significantly higher than those in the spleen and lymph nodes. These findings indicate the possibility that the surface phenotye of B cells is influenced by the microenvironment. To clarify the in vitro condition that supports the differentiation of thymic progenitor B cells, stroma cells. In the presence of IL-7, thymic stroma cells, but not stroma cells from the bone marrow nor thymic cell lines, could support the differentiation of thymic progenitor B cells.