Kotloff D B, Zitron I M, Cebra J J
Eur J Immunol. 1987 Jan;17(1):21-6. doi: 10.1002/eji.1830170105.
A modified splenic fragment assay was used to assess the role of antigen-specific helper T cells in B cell isotype expression. Limiting numbers of carrier-specific helper T cells from lines or clones were injected along with a source of B cells into lethally irradiated unprimed recipients. The incidence of lodging of the T cell lines in recipient spleens at 18 h was determined by autoradiography to be 1.5 to 4.3% of the injected cells. These T cells were necessary and sufficient for the generation of T-dependent B cell responses within splenic fragments cultured in vitro with specific antigen. A comparison of isotypic responses from splenic and Peyer's patch B cells generated with the same T cell population revealed that a high proportion of the response from Peyer's patch B cells consisted of IgA antibody exclusively (46-57%) while the percentage of such responses from splenic B cells was much lower (7-10%). Thus, the isotype pattern of the response reflected the B cell source. Experiments in which cloned hemocyanin-specific T cells provided help to T-depleted spleen cells within splenic fragments from athymic recipients indicated that a single specificity of helper T cell is both necessary and sufficient to support the generation of antibody responses consisting of multiple isotypes. Isotype-specific T cells do not appear to be required in this system.
采用改良的脾细胞片段分析法来评估抗原特异性辅助性T细胞在B细胞同种型表达中的作用。将来自细胞系或克隆的数量有限的载体特异性辅助性T细胞与B细胞来源一起注射到经致死剂量照射的未致敏受体中。通过放射自显影法测定，18小时时受体脾脏中T细胞系的着床率为注射细胞的1.5%至4.3%。这些T细胞对于在体外与特异性抗原一起培养的脾细胞片段中产生T细胞依赖性B细胞反应是必需且足够的。对由相同T细胞群体产生的脾细胞和派尔集合淋巴结B细胞的同种型反应进行比较发现，派尔集合淋巴结B细胞的反应中很大一部分仅由IgA抗体组成（46 - 57%），而脾细胞B细胞的此类反应百分比要低得多（7 - 10%）。因此，反应的同种型模式反映了B细胞来源。在实验中，克隆的血蓝蛋白特异性T细胞为无胸腺受体脾细胞片段中T细胞耗竭的脾细胞提供帮助，这表明辅助性T细胞的单一特异性对于支持产生由多种同种型组成的抗体反应既是必需的也是足够的。在该系统中似乎不需要同种型特异性T细胞。
