Mokyr M B, Colvin M, Dray S
Int J Immunopharmacol. 1985;7(1):111-22. doi: 10.1016/0192-0561(85)90016-5.
We have utilized 4-hydroperoxycyclophosphamide (4-HP-CY) as a probe for the immunomodulatory activity of the metabolites of cyclophosphamide (CY) since 4-HP-CY hydrolyzes spontaneously in aqueous solution to the same metabolites as those formed after in vivo conversion of CY by microsomal enzymes. Exposure of immunosuppressed MOPC-315 tumor bearer spleens to a low concentration of 4-HP-CY (0.1-3.0 micron) resulted in augmented antitumor immune potential. The level of antitumor immune potential exhibited by 4-HP-CY-treated tumor bearer spleen cells was not further augmented but was actually reduced by depletion of glass-adherent cells, a procedure which is effective in removing the cells known to have immunosuppressive activity (i.e. metastatic tumor cells and macrophages) from the spleen of untreated MOPC-315 tumor-bearing mice. In fac, 4-HP-CY was superior to depletion of glass-adherent cells in augmenting the antitumor immune potential of immunosuppressed tumor bearer spleen cells. When cells from the primary tumor nodule were incubated with a low concentration of 4-HP-CY which only marginally inhibited their proliferation, the drug completely abolished the suppressive activity of the cells for in vitro generation of antitumor cytotoxicity by normal spleen cells. Moreover, a high level of antitumor cytotoxicity developed when normal spleen cells were cultured in vitro with 4-HP-CY-treated tumor cells at a wide range of ratios of spleen cells to tumor cells. Thus, in the MOPC-315 tumor model, metabolites of CY eliminate the inhibitory effectiveness of splenic suppressor cells and induce the appearance of immunopotentiating activity. The results obtained with 4-HP-CY in vitro provide support for the hypothesis that low-dose CY therapy of mice bearing a large MOPC-315 tumor leads to the appearance of augmented antitumor immune potential in their hitherto immunosuppressed spleen cells as a result of the in situ immunomodulatory effect of the drug on cells in the spleen.
自4-氢过氧环磷酰胺（4-HP-CY）在水溶液中可自发水解为与环磷酰胺（CY）经微粒体酶体内转化后形成的相同代谢产物以来，我们一直将其用作CY代谢产物免疫调节活性的探针。将免疫抑制的MOPC-315荷瘤小鼠的脾脏暴露于低浓度的4-HP-CY（0.1 - 3.0微米）可增强抗肿瘤免疫潜能。4-HP-CY处理的荷瘤小鼠脾脏细胞所表现出的抗肿瘤免疫潜能水平，在通过去除玻璃黏附细胞（该方法可有效从未经处理的MOPC-315荷瘤小鼠脾脏中去除已知具有免疫抑制活性的细胞，即转移性肿瘤细胞和巨噬细胞）后，不仅没有进一步增强，实际上反而降低了。事实上，在增强免疫抑制的荷瘤小鼠脾脏细胞的抗肿瘤免疫潜能方面，4-HP-CY优于去除玻璃黏附细胞的方法。当将来自原发性肿瘤结节的细胞与仅轻微抑制其增殖的低浓度4-HP-CY一起孵育时，该药物完全消除了这些细胞对正常脾脏细胞体外产生抗肿瘤细胞毒性的抑制活性。此外，当正常脾脏细胞与经4-HP-CY处理的肿瘤细胞以广泛的脾细胞与肿瘤细胞比例在体外培养时，会产生高水平的抗肿瘤细胞毒性。因此，在MOPC-315肿瘤模型中，CY的代谢产物消除了脾脏抑制细胞的抑制作用，并诱导出免疫增强活性。在体外使用4-HP-CY获得的结果支持了这样一种假说，即对携带大的MOPC-315肿瘤的小鼠进行低剂量CY治疗，会导致其迄今免疫抑制的脾脏细胞中出现增强的抗肿瘤免疫潜能，这是由于药物对脾脏细胞的原位免疫调节作用所致。
