The aim of this WP is to develop new in vitro models for PAD study. Each partner has his own approach but all are complementary and converge to the same objective, i.e. the molecular characterization of PAD. By a close collaboration between all groups, 3 main objectives will be reached.
A.Better characterization of PAD, including phenotypic and functional B cell studies.
B.Validation of gene mutations
C.In vitro search for new genetic defects
TACI C104R accounts for about 50% of all TACI-mutated alleles in CVID patients. One of the aims of U. Salzer's group in this study is to use existing monoclonal or polyclonal antibodies or generate these reagents to analyse the mutated C104R protein.
Study of normal antibody maturation processes in normal and pathological conditions.
Immunoglobulin class switch recombination (CSR)-deficiencies are a rare (1/200,000 births) inherited disease characterized by increased (or normal) IgM serum levels contrasting with a strong decrease or an absence of other isotypes (IgG, IgA). According to the molecular defect, this Ig-CSR deficiency is associated or not with a defective generation of somatic hypermutations (SHM). Several molecular defects underlie this condition. We have contributed to the description of CD40-ligand and CD40-deficiencies which both lead to a severe cellular and humoral immunodeficiency.
Plasma cell development and potential defects in functions required to generate plasma cells were studied in Freiburg and in Brescia through the collaboration between the groups of A. Plebani and H. Eibel.
The expansion of specific B cell subsets expressing low levels of CD21 in patients with PAD is an expression of an underlying pathogenetic dysregulation. These B cell subsets will be used to define subgroups of patients for specific functional as well as molecular characterization. Circulating B cell populations with a low expression of CD21 contain transitional B cells, activated CD21low B cells and possibly plasmablasts.
In order to identify transcripts affected by BTK deficiency, E. Smith's group has performed several experiments. First, they have created a new database for immune-related genes as an important tool for screening targets for shRNA-based knockdown. This database contains 1982 immune genes and combines information from 3 already existing databases: Immunogenetic Related Information Source (IRIS) - a database surveying known human immune system genes, Immunome Knowledge Base (IKB) - an integrated service for immunome research, and Gene Ontology assigned 'immune response' genes.