Alves-Rosa M F, Vulcano M, Beigier M, Breyer I, Isturiz M A
Divisíon Immunología, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina.
Immunol Lett. 1999 Nov 1;70(2):119-26. doi: 10.1016/s0165-2478(99)00125-x.
We have previously demonstrated that N-formyl-methionyl-leucyl-phenylalanine (FMLP) induces down-regulation of FcgammaRs on human neutrophils (PMN) modifying different FcgammaR-dependent functions. The aim of this work was to assess the cellular mechanisms by which FMLP exerts this effect on FcgammaRs. The role of the microfilament and cytoskeletal apparatus in this process was evaluated using cytochalasin B (CB), an inhibitor of microfilament functions. The expression of FcgammaRIIIB and FcgammaRII after CB + FMLP treatment was drastically diminished when compared to FMLP-treated cells. Neutrophil degranulation induced by FMLP affect only 22% of the cells in response to FMLP. However, the FcgammaRs of the whole PMN population were reduced, suggesting that secretory products could be responsible for the down-regulation induced by FMLP or FMLP + CB. In fact, supernatants from FMLP-treated PMN also induced FcyRs down-regulation on naive neutrophils. Moreover, supernatants from FMLP + CB-treated PMNs exerted a higher effect. Data obtained from permeabilized PMN show that after FMLP treatment there is an intracellular depletion of both FcgammaRIIIB and FcgammaRII. In addition, the FcgammaR down-regulation is abrogated by phenyl methyl sulfonyl fluoride (PMSF) but not by other protease inhibitors such as pepstatin, thiorphan, phosphoramidon and leupeptin, suggesting a role for serine protease(s) in this process.
我们之前已经证明，N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（FMLP）可诱导人中性粒细胞（PMN）上FcγRs的下调，从而改变不同的FcγR依赖性功能。这项工作的目的是评估FMLP对FcγRs产生这种作用的细胞机制。使用细胞松弛素B（CB）（一种微丝功能抑制剂）评估微丝和细胞骨架装置在此过程中的作用。与FMLP处理的细胞相比，CB + FMLP处理后FcγRIIIB和FcγRII的表达急剧减少。FMLP诱导的中性粒细胞脱颗粒仅影响22%对FMLP有反应的细胞。然而，整个PMN群体的FcγRs减少，这表明分泌产物可能是FMLP或FMLP + CB诱导下调的原因。事实上，FMLP处理过的PMN的上清液也能诱导未致敏中性粒细胞上FcyRs的下调。此外，FMLP + CB处理过的PMN的上清液作用更强。从透化的PMN获得的数据表明，FMLP处理后，FcγRIIIB和FcγRII在细胞内均有消耗。此外，苯甲基磺酰氟（PMSF）可消除FcγR的下调，但胃蛋白酶抑制剂、硫氧还蛋白、磷酰胺脒和亮抑酶肽等其他蛋白酶抑制剂则不能，这表明丝氨酸蛋白酶在这一过程中发挥作用。
