Auladell Maria, Nguyen Thi Ho, Garcillán Beatriz, Mackay Fabienne, Kedzierska Katherine, Fox Annette
Department of Microbiology and Immunology University of Melbourne at the Peter Doherty Institute for Infection and Immunity Melbourne VIC Australia.
WHO Collaborating Centre for Reference and Research on Influenza VIDRL at the Peter Doherty Institute for Infection and Immunity Melbourne VIC Australia.
Clin Transl Immunology. 2019 Nov 13;8(11):e01090. doi: 10.1002/cti2.1090. eCollection 2019.
A fundamental question in influenza research is whether antibody titre decline upon successive exposure to variant strains is consequent to recall of cross-reactive memory B cells that competitively inhibit naive B-cell responses. In connection, it is not clear whether naive and memory B cells remain phenotypically distinct acutely after activation such that they may be distinguished .
Here, we first compared the capacity of anti-Ig and Toll-like-receptor (TLR) 7/8 and TLR9 agonists (R848 and CpG) to augment human B-cell differentiation induced by IL-21 and sCD40L. The conditions that induced optimal differentiation were then used to compare the post-activation phenotype of sort-purified naive and memory B-cell subsets by FACS and antibody-secreting cell (ASC) ELISPOT.
Sort-purified naive and memory B cells underwent robust plasmablast and ASC formation when stimulated with R848, but not CpG, and co-cultured with monocytes. This coincided with increased IL-1β and IL-6 production when B cells were co-cultured with monocytes and stimulated with R848, but not CpG. Naive B cells underwent equivalent ASC generation, but exhibited less class-switch and modulation of CD27, CD38 and CD20 expression than memory B cells after stimulation with R848 and monocytes for 6 days.
Stimulation with R848, IL-21 and sCD40L in the presence of monocytes induces robust differentiation and ASC generation from both naive and memory B-cells. However, naive and memory B cells retain key phenotypic differences after activation that may facilitate discrimination and better characterisation of acute responses to variant antigens.
流感研究中的一个基本问题是，在连续接触变异株后抗体滴度下降是否是由于交叉反应性记忆B细胞的回忆，从而竞争性抑制幼稚B细胞反应。与此相关的是，尚不清楚幼稚B细胞和记忆B细胞在激活后短期内是否在表型上仍保持不同，以便能够区分它们。
在此，我们首先比较了抗免疫球蛋白、Toll样受体（TLR）7/8和TLR9激动剂（R848和CpG）增强IL-21和可溶性CD40配体诱导的人B细胞分化的能力。然后，使用诱导最佳分化的条件，通过荧光激活细胞分选术（FACS）和抗体分泌细胞（ASC）酶联免疫斑点法比较分选纯化的幼稚B细胞和记忆B细胞亚群激活后的表型。
分选纯化的幼稚B细胞和记忆B细胞在用R848刺激而非CpG刺激并与单核细胞共培养时，会经历强大的浆母细胞和ASC形成。这与B细胞与单核细胞共培养并用R848而非CpG刺激时IL-1β和IL-6产生增加相一致。幼稚B细胞产生的ASC数量相当，但在用R848和单核细胞刺激6天后，与记忆B细胞相比，其类别转换以及CD27、CD38和CD20表达的调节较少。
在单核细胞存在的情况下，用R848、IL-21和可溶性CD40配体刺激可诱导幼稚B细胞和记忆B细胞发生强大的分化并产生ASC。然而，幼稚B细胞和记忆B细胞在激活后仍保留关键的表型差异，这可能有助于区分和更好地表征对变异抗原的急性反应。
