Ono S, Hayashi S, Takahama Y, Dobashi K, Katoh Y, Nakanishi K, Paul W E, Hamaoka T
J Immunol. 1986 Jul 1;137(1):187-96.
We demonstrated previously that cellfree supernatant of the B151K12 T cell hybridoma (B151-CFS) contained T cell-replacing factor (here in after referred to as B151-TRF1) capable of inducing growth and differentiation of antigen-activated B cells into antigen-specific plaque-forming cells (PFC). In the present study, we have identified in B151-CFS another unique lymphokine activity (referred to as B151-TRF2), which induces polyclonal differentiation of unstimulated B cells into IgM-secreting cells without concomitant stimulation of antigen, mitogen, or anti-Ig antibody. The B151-TRF2 activity induced polyclonal IgM PFC responses via the action on surface Ig-positive small resting B cells from normal unprimed mice. This activation was effective across an H-2 barrier, and apparently independent of the presence of T cells and accessory cells. Interestingly, the B151-TRF2 activity notably stimulated B cells of neonatal and mutant DBA/2Ha mice, which are nonresponders to B151-TRF1, whereas it failed to activate the xid B cells from CBA/N mice. To substantiate that B151-TRF1 and B151-TRF2 activities are mediated by mutually distinguishable molecules, an absorption experiment of B151-CFS was performed by utilizing DBA/2Ha B cells which are lacking in B151-TRF1 receptor. It was found that DBA/2Ha B cells could absorb B151-TRF2 activity but not B151-TRF1 activity. In contrast, murine chronic B cell leukemia BCL1 cells, which were shown to differentiate into IgM-secreting cells by stimulation with B151-CFS, selectively removed B151-TRF1 activity but not B151-TRF2 activity. Furthermore, biochemical analysis revealed that the B151-TRF2 was a heat (56 degrees C for 30 min)-sensitive protein with an apparent m.w. of 30,000 by gel filtration, whereas B151-TRF1 was a heat-resistant glycoprotein with m.w. of 50,000. In addition, it was shown that prostaglandin E2 selectively inhibited B151-TRF2-mediated B cell responses. These results demonstrate clearly that B151-TRF1 and B151-TRF2 are distinct B cell differentiation factors involved in the different activation pathways of distinct B cell subpopulations. The immunologic implication of B151-TRF2 activity in B cell differentiation is discussed in comparison with other lymphokines so far reported to activate small resting B cells.
我们之前证实，B151K12 T细胞杂交瘤的无细胞上清液（B151 - CFS）含有能够诱导抗原激活的B细胞生长并分化为抗原特异性噬斑形成细胞（PFC）的T细胞替代因子（以下简称B151 - TRF1）。在本研究中，我们在B151 - CFS中鉴定出另一种独特的淋巴因子活性（称为B151 - TRF2），它可诱导未受刺激的B细胞多克隆分化为分泌IgM的细胞，而无需抗原、丝裂原或抗Ig抗体的伴随刺激。B151 - TRF2活性通过作用于正常未致敏小鼠表面Ig阳性的小静止B细胞诱导多克隆IgM PFC反应。这种激活在H - 2屏障上有效，并且显然独立于T细胞和辅助细胞的存在。有趣的是，B151 - TRF2活性显著刺激新生和突变DBA/2Ha小鼠的B细胞（这些小鼠对B151 - TRF1无反应），而未能激活CBA/N小鼠的xid B细胞。为了证实B151 - TRF1和B151 - TRF2活性由相互可区分的分子介导，利用缺乏B151 - TRF1受体的DBA/2Ha B细胞进行了B151 - CFS的吸收实验。发现DBA/2Ha B细胞可吸收B151 - TRF2活性但不能吸收B151 - TRF1活性。相反，鼠慢性B细胞白血病BCL1细胞经B151 - CFS刺激后可分化为分泌IgM的细胞，它选择性去除B151 - TRF1活性而不是B151 - TRF2活性。此外，生化分析显示B151 - TRF2是一种对热（56℃ 30分钟）敏感的蛋白质，通过凝胶过滤法测得其表观分子量为30,000，而B151 - TRF1是一种分子量为50,000的耐热糖蛋白。另外，已表明前列腺素E2选择性抑制B151 - TRF2介导的B细胞反应。这些结果清楚地表明B151 - TRF1和B151 - TRF2是不同的B细胞分化因子，参与不同B细胞亚群的不同激活途径。与迄今报道的其他激活小静止B细胞的淋巴因子相比，讨论了B151 - TRF2活性在B细胞分化中的免疫学意义。
