Anti-CD19 Monoclonal antibody, clone IJC20 [PE/Cy7®]

We previously showed that anti-neutrophil extracellular trap (NET) rheumatoid arthritis (RA)-rmAbs derived from CD19(+) B cells within RA human synovial tissues frequently react against NETs. In this study, we aimed to characterize the importance of affinity maturation via somatic hypermutation (SHM) within the Ig variable H (VH) and variable L (VL) chains and Fab-N-linked glycosylation in RA synovial B cell clones reactive to NETs and NET-derived Ags such as citrullinated histones. Selected anti-NET RA-rmAbs derived from synovial RA CD19(+) B cells were subjected to overlap-PCR to generate germline (GL; VH and VL reverted into GL), hybrid clones (VH/VL region reverted into GL), and N-glycosylation mutants (N -> Q) and analyzed for anti-NETs and citrullinated histones (cit-H2B) immunoreactivity. Anti-NET/cit-H2B immunoreactivity of selected RA-rmAbs was abrogated in the VH and VL GL counterpart. In RA B cell hybrid clone RA015/11.88 and RA056/11.23.2, NETand/or cit-H2B immunoreactivity was solely dependent on SHM in the IgVH region whereas RA B cell hybrid clone RA015/11.91 required affinity maturation of both VH and VL for efficient binding to cit-H2B. In 7/80 RA-rmAb, SHM resulted in ex novo N-glycosylation sites in VH and/or VL regions. Removal of Fab-linked glycans in RA056/11.23.2 in the N-mutant counterpart resulted in 90% reduction in immunoreactivity to cit-H2B. Thus, SHM in the IgVH and/or VL regions of RA synovial B cells is necessary for the immunoreactivity to NET-Ags. Fab-N-linked-glycosylation introduction sites are observed in a minority of anti-NET B cell clones but can strongly influence NET-Ag binding.

Immunocompromised patients may be at increased risk to develop COVID-19 during the 2019 beta-coronavirus infection. We present the unique opportunity we had to monitor the liver, IL-6 and immune cell course before, during and after COVID-19 in a boy with autoimmune hepatitis (AIH) and type 1 diabetes (T1D). CD4(+)and CD8(+)T cells frequencies decreased because of prednisolone, followed by a plateauing increase whereas CD19(+)CD20(+)B cell increased strongly and was unaffected by COVID-19 infection. Moreover, the percentage of activated CD8(+)T cells expressing HLA-DR (CD8(+)HLA-DR+) increased during COVID-19 and subsided after its clearance. Total regulatory T cells (Tregs: CD4(+)CD25(+)CD127(low)FOXP3(+)) remained stable. Although activated Tregs (CD4(+)CD45RA(-)FOXP3(high)) strongly increased upon prednisolone, it decreased afterwards. Furthermore, regulatory B cells (Bregs: CD19(+)CD20(+)CD24(high)CD38(high)) declined sharply owing to prednisolone. Serum IL-6 remained undetectable at all times. We demonstrated for the first time immune monitoring in a child with AIH and T1D before, during and after COVID-19. We hypothesize that continuing with low level of prednisolone without azathioprine may have abrogated activated Tregs, Bregs and IL-6 production and therefore permitting the activation of CD8(+)T cells, clearing the virus. Copyright (c) 2020 Wolters Kluwer Health, Inc. All rights reserved.