Brett S J, Rhodes J, Liew F Y, Tite J P
Department of Cell Biology, Wellcome Research Laboratories, Beckenham, Kent, UK.
J Immunol. 1993 Apr 1;150(7):2869-84.
Rationally attenuated strains of Salmonella expressing foreign proteins represent a potentially important vaccine delivery system. The characteristics of Ag presentation of influenza nucleoprotein expressed in an AroA- strain of Salmonella typhimurium (SL3262-pNP-2) have therefore been compared with those of soluble purified nucleoprotein (NP) and infectious influenza virus. This represents three distinct modes of internalization of the same protein into APC. Human monocytes and the monocytic leukemia cell line THP-1 infected with SL3261-pNP-2 were found to present several different epitopes from NP to human CD4+ class II-restricted T lymphocytes. Ag presentation to these T cell clones was enhanced by pretreatment of THP-1 cells with IFN-gamma but not TNF-alpha. Bacterial phagocytosis and Ag presentation of NP were increased after opsonization of Salmonella with immune serum. Macrophages infected with SL3261-pNP-2 were unable to present NP to class I-restricted T cells. In contrast, cells infected with live influenza virus, although recognized by NP-specific class I-restricted CTL, were inefficiently recognized by NP-specific class II-restricted T cells. Ag presentation to CD4+ T cell clones by monocytes of SL3261-pNP-2, purified recombinant NP, and live influenza virus, but not the synthetic peptide 206-229, was inhibited by chloroquine and the protease inhibitors pepstatin A and leupeptin, suggesting that the major route of processing in each case was via the exogenous pathway. T cell recognition of NP via all of these Ag delivery systems was also abrogated by cycloheximide and brefeldin A treatment, indicating a requirement for recently synthesized MHC class II molecules in presentation of whole NP after processing but not for the corresponding synthetic peptide.
表达外源蛋白的鼠伤寒沙门氏菌合理减毒株代表了一种潜在的重要疫苗递送系统。因此，研究人员比较了在鼠伤寒沙门氏菌AroA-菌株（SL3262-pNP-2）中表达的流感核蛋白的抗原呈递特性与可溶性纯化核蛋白（NP）和感染性流感病毒的抗原呈递特性。这代表了同一蛋白进入抗原呈递细胞（APC）的三种不同内化模式。研究发现，感染SL3261-pNP-2的人单核细胞和单核细胞白血病细胞系THP-1能够向人CD4+ II类限制性T淋巴细胞呈递NP的几种不同表位。用IFN-γ预处理THP-1细胞可增强对这些T细胞克隆的抗原呈递，但用TNF-α预处理则无此作用。用免疫血清调理沙门氏菌后，细菌吞噬作用和NP的抗原呈递增加。感染SL3261-pNP-2的巨噬细胞无法向I类限制性T细胞呈递NP。相比之下，感染活流感病毒的细胞虽然能被NP特异性I类限制性细胞毒性T淋巴细胞（CTL）识别，但被NP特异性II类限制性T细胞识别的效率较低。氯喹以及蛋白酶抑制剂胃蛋白酶抑制剂A和亮抑酶肽可抑制SL3261-pNP-2的单核细胞、纯化的重组NP和活流感病毒向CD4+ T细胞克隆呈递抗原，但合成肽206-229则不受影响，这表明在每种情况下，主要的加工途径都是通过外源性途径。用放线菌酮和布雷菲德菌素A处理也会消除通过所有这些抗原递送系统对NP的T细胞识别，这表明在加工后呈递完整NP时需要最近合成的MHC II类分子，但对相应的合成肽则不需要。
