CHU Nantes, Université de Nantes, Inserm, Centre de Recherche en Transplantation et Immunologie, UMR 1064, ITUN, F-44000 Nantes, France.
Labex IGO, 44000 Nantes, France; and.
J Immunol. 2020 Nov 1;205(9):2391-2401. doi: 10.4049/jimmunol.2000335. Epub 2020 Sep 18.
Granzyme B-expressing B cells have been shown to be an important regulatory B cell subset in humans. However, it is unclear which subpopulations of B cells express GZMB under normal conditions and which protocols effectively induce ex vivo expansion of GZMB B cells. We found that in the peripheral blood of normal individuals, plasmablasts were the major B cell subpopulation that expressed GZMB. However, when using an in vitro plasmablast differentiation protocol, we obtained only 2% GZMB B cells. Nevertheless, using an expansion mixture containing IL-21, anti-BCR, CpG oligodeoxynucleotide, CD40L, and IL-2, we were able to obtain more than 90% GZMB B cells after 3 d culture. GZMB B cells obtained through this protocol suppressed the proliferation of autologous and allogenic CD4CD25 effector T cells. The suppressive effect of GZMB B cells was partially GZMB dependent and totally contact dependent but was not associated with an increase in effector T cell apoptosis or uptake of GZMB by effector T cells. Interestingly, we showed that GZMB produced by B cells promoted GZMB B cell proliferation in ERK1/2-dependent manner, facilitating GZMB B cell expansion. However, GZMB B cells tended to undergo apoptosis after prolonged stimulation, which may be considered a negative feedback mechanism to limit their uncontrolled expansion. Finally, we found that expanded GZMB B cells exhibited a regulatory phenotype and were enriched in CD307b, CD258CD72, and CD21loPD-1 B cell subpopulations. Our study, to our knowledge, provides new insight into biology of GZMB B cells and an efficient method to expand GZMB B cells for future cell therapy applications.
颗粒酶 B 表达 B 细胞已被证明是人类中一种重要的调节性 B 细胞亚群。然而，目前尚不清楚在正常条件下哪些 B 细胞亚群表达 GZMB，以及哪些方案能有效地诱导 GZMB B 细胞的体外扩增。我们发现，在正常人的外周血中，浆母细胞是表达 GZMB 的主要 B 细胞亚群。然而，当使用体外浆母细胞分化方案时，我们仅获得了 2%的 GZMB B 细胞。尽管如此，使用含有 IL-21、抗 BCR、CpG 寡脱氧核苷酸、CD40L 和 IL-2 的扩增混合物，我们在 3 d 的培养后能够获得超过 90%的 GZMB B 细胞。通过该方案获得的 GZMB B 细胞抑制了自体和同种异体 CD4CD25 效应 T 细胞的增殖。GZMB B 细胞的抑制作用部分依赖于 GZMB，完全依赖于接触，但与效应 T 细胞凋亡的增加或 GZMB 被效应 T 细胞摄取无关。有趣的是，我们发现 B 细胞产生的 GZMB 通过 ERK1/2 依赖性方式促进 GZMB B 细胞增殖，从而促进 GZMB B 细胞的扩增。然而，GZMB B 细胞在长时间刺激后往往会发生凋亡，这可能被视为一种负反馈机制，以限制其不受控制的扩增。最后，我们发现扩增的 GZMB B 细胞表现出调节表型，并富集在 CD307b、CD258CD72 和 CD21loPD-1 B 细胞亚群中。据我们所知，我们的研究为 GZMB B 细胞的生物学提供了新的见解，并为未来的细胞治疗应用提供了一种有效扩增 GZMB B 细胞的方法。
