DeFranco A L, Ashwell J D, Schwartz R H, Paul W E
J Exp Med. 1984 Mar 1;159(3):861-80. doi: 10.1084/jem.159.3.861.
Resting B lymphocytes are activated, proliferate, and differentiate into antibody-secreting cells when cultured with long-term lines of major histocompatibility complex (MHC)-restricted, antigen-specific T cell in the presence of the antigen for which the T cells are specific. Under optimal conditions, essentially all B cells are activated and approximately 35% enter S phase in the absence of antigens for which the B cells are specific. Activation and proliferation are observed in cells from both normal mice and mice with the xid-determined immune defect. Highly purified B cells bearing Ia molecules for which the T cells are "cospecific" can present antigen to T cells with the resulting T cell stimulation leading to the activation and proliferation of the antigen-presenting B cells. However, B cells that do not bear Ia molecules for which the T cells are cospecific are also activated and proliferate if antigen and a source of antigen-presenting B cells or macrophage-rich cells of proper histocompatibility type are present. Thus, resting B cells, both normal and "xid", can be activated by non-MHC restricted factors without receptor cross-linkage. Experiments are presented that support the concept that local production and action of such unrestricted activating factors may be responsible for the MHC-restriction of T cell-B cell interaction seen in many circumstances.
当在存在T细胞所特异性识别抗原的情况下，将静止的B淋巴细胞与主要组织相容性复合体（MHC）限制性、抗原特异性T细胞的长期细胞系共同培养时，B淋巴细胞会被激活、增殖并分化为抗体分泌细胞。在最佳条件下，即使不存在B细胞所特异性识别的抗原，基本上所有B细胞也会被激活，约35%的B细胞进入S期。在正常小鼠和具有xid免疫缺陷的小鼠的细胞中均观察到激活和增殖现象。带有T细胞“共特异性”Ia分子的高度纯化B细胞能够将抗原呈递给T细胞，从而导致T细胞受到刺激，进而使呈递抗原的B细胞激活和增殖。然而，如果存在抗原以及呈递抗原的B细胞来源或具有适当组织相容性类型的富含巨噬细胞的细胞，那些不带有T细胞共特异性Ia分子的B细胞也会被激活并增殖。因此，正常和“xid”的静止B细胞都可以被非MHC限制性因子激活，而无需受体交联。本文所展示的实验支持这样一种观点，即在许多情况下，此类非限制性激活因子的局部产生和作用可能是T细胞与B细胞相互作用的MHC限制性的原因。
