Giovarelli M, Santoni A, Jemma C, Musso T, Giuffrida A M, Cavallo G, Landolfo S, Forni G
Institute of Microbiology, University of Turin, Italy.
J Immunol. 1988 Oct 15;141(8):2831-6.
The biological role of the murine IFN-gamma endogenously secreted during cell activation has been probed by the use of a rat mAb (AN18) that specifically neutralizes its activity. When An18 mAb is added to the cultures of BALB/c and C57BL/6 nylon nonadherent spleen cells (naSpc) stimulated for 18 h with 1000 U of IL-2, the normally released IFN-gamma can no longer be detected in the supernatants and the IL-2-induced proliferative response is markedly reduced as compared with control cultures set up in the presence of an unrelated rat mAb. By contrast, the increased natural cytotoxicity is not affected. The 96-h culture of both BALB/c and C57BL/6 naSpc in the presence of 1000 U of IL-2 resulted in marked lymphocyte proliferation and generation of lymphokine-activated killer activity. The presence of An18 mAb strongly inhibited both functions. Similarly, when naSpc were stimulated with mitomycin C-inactivated allogeneic leukocytes in the presence of An18 mAb, the normal proliferative response and specific cytotoxicity were almost abolished, whereas the secretion of IL-2 was in no way affected. Lymphocytes recovered from 3-day cultures stimulated by IL-2 or allogeneic cells in the presence of An18 mAb displayed a decrease of the expression of the p55 chain of IL-2R, as shown by flow cytofluorimetry. Moreover, binding experiments with 125I-labeled IL-2 showed that lymphocytes from allostimulated cultures set up in the presence of An18 mAb display a decreased number of low affinity and almost no high affinity IL-2R as compared with control cultures. These data show that endogenous IFN-gamma plays an obligatory role for the de novo induction of cytolytic activity in lymphokine-activated killer cells and CTL, most probably by affecting the membrane expression of high affinity IL-2R.
利用一种能特异性中和其活性的大鼠单克隆抗体（AN18），对细胞活化过程中内源性分泌的小鼠γ干扰素的生物学作用进行了探究。当将An18单克隆抗体添加到用1000 U白细胞介素-2刺激18小时的BALB/c和C57BL/6尼龙非黏附脾细胞（naSpc）培养物中时，上清液中无法再检测到正常释放的γ干扰素，并且与存在无关大鼠单克隆抗体的对照培养物相比，白细胞介素-2诱导的增殖反应明显降低。相比之下，自然细胞毒性的增加不受影响。在1000 U白细胞介素-2存在的情况下，对BALB/c和C57BL/6 naSpc进行96小时培养，导致淋巴细胞显著增殖并产生淋巴因子激活的杀伤活性。An18单克隆抗体的存在强烈抑制了这两种功能。同样，当在An18单克隆抗体存在的情况下用丝裂霉素C灭活的同种异体白细胞刺激naSpc时，正常的增殖反应和特异性细胞毒性几乎完全消失，而白细胞介素-2的分泌则完全不受影响。如流式细胞荧光术所示，从在An18单克隆抗体存在的情况下用白细胞介素-2或同种异体细胞刺激3天的培养物中回收的淋巴细胞，显示白细胞介素-2R p55链的表达降低。此外，用125I标记的白细胞介素-2进行的结合实验表明，与对照培养物相比，在An18单克隆抗体存在的情况下建立的同种异体刺激培养物中的淋巴细胞，低亲和力白细胞介素-2R数量减少，几乎没有高亲和力白细胞介素-2R。这些数据表明，内源性γ干扰素在淋巴因子激活的杀伤细胞和细胞毒性T淋巴细胞中对细胞溶解活性的从头诱导起着必不可少的作用，很可能是通过影响高亲和力白细胞介素-2R的膜表达来实现的。
