X-linked hyper-IgM Syndrome (XHIGM) is caused by a mutation of CD40 ligand (CD40L), which is normally expressed on activated CD4+ T cells and is responsible for immunoglobulin class switching. A 7-year-old boy with recurrent sino-pulmonary infections since the age of 3 months had normal CD3+, CD4+, CD8+T lymphocytes, and CD19+B lymphocytes and NK cells, but significantly elevated IgM and extrem...

Understanding how class switch recombination (CSR) is regulated to produce immunoglobulin E (IgE) has become fundamental because of the dramatic increase in the prevalence of IgE-mediated hypersensitivity reactions. CSR requires the induction of the enzyme AICDA in B cells. Mutations in AICDA have been linked to Hyper-IgM syndrome (HIGM2), which shows absence of switching to IgE as well as to I...

the link between il-13 and bronchial hyper-responsiveness has brought this cytokine as a potential therapeutic target for asthma and allergic diseases. at the present study, we address the role of b cell derived il-13 in the ige and other immunoglobulin development. antisense oligo for human il-13 m-rna was used to study ige down regulation. human b-lymphocytes were purified by positive selecti...

Somatic hypermutation normally occurs as a consequence of the expression of activation-induced cytidine deaminase (AID) by Ag-activated, mature B cells during T cell-dependent germinal center responses. Nonetheless, despite their inability to express CD154 and initiate GC responses, patients with type 1 hyper-IgM syndrome (HIGM1) support populations of IgM(+)IgD(+)CD27(+) B cells that express m...

B-chronic lymphocytic leukemias (B-CLL) represent expanded clones of resting B lymphocytes that mostly express surface IgM (sIgM). The present study shows that B-CLL cells, freshly isolated from two patients, were sIgM+, sIgG-, and sIgA- but expressed IgG and IgA transcripts. cDNA cloning and sequencing showed that the VDJ segments associated to gamma and alpha heavy chain transcripts are ident...