Arianna Troilo, Germany

University of Freiburg Rheumatology and clinical immunology

Presenter Of 1 Presentation

Poster Display B Cell Biology

DYNAMIC IN VITRO MODELING OF HUMAN B CELL DEVELOPMENT DISSECTS EARLY DEVELOPMENTAL DEFECTS IN PRIMARY ANTIBODY DEFICIENCY.

Lecture Time
10:06 - 10:07
Room
Poster Area
Date
19.09.2019, Thursday
Session Time
10:00 - 17:00
Board Number
16
Presentation Topic
B Cell Biology

Abstract

Background and Aims

Bone marrow (BM) analysis shows that 20% of CVID patients harbor a defect at an early stage of B-cell development. The aim of this work is to study the mechanisms of the developmental block observed in a subgroup of CVID patients with increased risk of malignancy.

Methods

We set up a feeder-free cultivation system, that in healthy donors leads to the development of common lymphocyte progenitors (CLP) until the stage of IgM+ Immature B-cells. BM-CD34+ cells are expanded in the presence of a cytokine cocktail for two weeks and then cells are cultivated in cytokine-free medium up to day 49 and analyzed weekly by flow cytometry.

Results

CD34+ cells from 15 CVID patients, 9 of which presented a block at early stages of development, and 2 Btk-deficient patients were tested in vitro. As expected CD34+ cells from patients with normal B-cell development in vivo developed into lymphocyte progenitors until the stage of IgM+ Immature-B cells, while in Btk-deficient patients the development arrested at Pre-B-cell stage. Among CVID patients presenting a block in development, 3 could not reach the immature B-cell stage, while 6 could develop in vitro until the stage of IgM+ B cells, even though 2 of the latter patients presented a progressive exhaustion of the CLP compartment.

Conclusions

We identified four groups: (1) with intrinsic B-cell defect, (2) with possible defect in the BM microenvironment impairing early stages of B-cell development (3) with defect in repopulation of CLP compartment and (4) with normal B-cell development.

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