Moreno J, Lipsky P E
J Immunol. 1986 May 15;136(10):3579-87.
The capacity of paraformaldehyde-fixed human antigen-presenting cells (APC) to induce responses by autologous, freshly isolated peripheral blood T4 cells was examined and was compared with their ability to stimulate allogeneic T4 cell DNA synthesis. Fixation of glass-adherent cells (AC) with as little as 0.06% paraformaldehyde abolished leucine incorporation, whereas fixation with 0.75% paraformaldehyde caused death of greater than 98% of the AC. Control APC were able to take up and present the soluble antigens streptokinase-streptodornase (SK-SD), tetanus toxoid, or tuberculin-purified protein derivative to autologous Ia-depleted T4 cells. Fixation with greater than 0.06% paraformaldehyde eliminated such ability. When AC were incubated with antigen overnight and were then fixed, however, they were able to present nominal antigen to autologous T4 cells in a genetically restricted manner that was blocked by monoclonal antibodies directed against monomorphic determinants on class II major histocompatibility complex (MHC) molecules. Despite the ability to present nominal antigen, paraformaldehyde-fixed AC were unable to induce allogeneic T4 cell proliferation. Similar results were observed when non-T cells or spleen cells were used as stimulators. The inability of fixed APC to stimulate allogeneic T4 cell DNA synthesis was not reversed by increasing the number of fixed APC or by the addition of control AC autologous to the responding cells. Moreover, interleukins 1 and 2 either alone or in combination also failed to permit maximal T cell proliferation in response to fixed allogeneic APC. The differential effects of fixation on nominal antigen and alloantigen presentation could not be explained by the loss of membrane thymocyte stimulatory activity on fixed AC. These results indicate that antigen-bearing fixed APC are competent to stimulate proliferation by antigen-reactive T4 cells, but are deficient at inducing allogeneic T4 cell DNA synthesis. The differential sensitivity of these two Ia-restricted functions of APC to chemical denaturation (reductive methylation) by paraformaldehyde suggests that the allodeterminants and restriction elements for nominal antigen on MHC class II molecules can be functionally dissociated.
研究了多聚甲醛固定的人抗原呈递细胞（APC）诱导自体新鲜分离的外周血T4细胞反应的能力，并将其与刺激同种异体T4细胞DNA合成的能力进行了比较。用低至0.06%的多聚甲醛固定玻璃贴壁细胞（AC）可消除亮氨酸掺入，而用0.75%的多聚甲醛固定则导致超过98%的AC死亡。对照APC能够摄取并将可溶性抗原链激酶-链道酶（SK-SD）、破伤风类毒素或结核菌素纯化蛋白衍生物呈递给自体Ia耗尽的T4细胞。用大于0.06%的多聚甲醛固定会消除这种能力。然而，当AC与抗原孵育过夜后再固定时，它们能够以基因限制的方式将名义抗原呈递给自体T4细胞，这种呈递被针对II类主要组织相容性复合体（MHC）分子上单一型决定簇的单克隆抗体所阻断。尽管能够呈递名义抗原，但多聚甲醛固定的AC无法诱导同种异体T4细胞增殖。当使用非T细胞或脾细胞作为刺激物时，也观察到了类似的结果。固定的APC无法刺激同种异体T4细胞DNA合成，增加固定APC的数量或添加与反应细胞自体的对照AC也无法逆转这种情况。此外，白细胞介素1和2单独或联合使用也无法使T细胞对固定的同种异体APC产生最大增殖反应。固定对名义抗原和同种异体抗原呈递的不同影响不能用固定AC上膜胸腺细胞刺激活性的丧失来解释。这些结果表明，携带抗原的固定APC有能力刺激抗原反应性T4细胞增殖，但在诱导同种异体T4细胞DNA合成方面存在缺陷。APC这两种Ia限制功能对多聚甲醛化学变性（还原甲基化）的不同敏感性表明，MHC II类分子上名义抗原的同种异体决定簇和限制元件在功能上可以分离。
