Eosinophil disorders are a range of heterogeneous diseases, which manifest as persistent increase of eosinophile granulocyte in blood and tissue, and may cause microenvironment change and irreversible chronic organ damage. According to World Health Organization, eosinophil diseases were divided into hypereosinophilia (HE) and hypereosinophilia syndrome (HES) by whether the organ is involved. Besides familial HE, HE were also divided into secondary (reactive) HE, primary (clonal/neoplastic) HE, and idiopathic HE. Lymphocytic variant HE is a special kind of secondary HE. With the study of the molecular mechanism of lymphocytic variant HE, the diagnosis is gradually clear. Moreover, some targeted therapeutic drugs, such as anti IL-5 monoclonal antibody (Mepolizumab) and anti CD 52 monoclonal antibody (Alemtuzumab) were also appeared. In this paper, the current basic and clinical researches of lymphocytic variant HE are reviewed.

Toll-like receptors(TLR) are widely exist in antigen presenting cells as a kind of pattem recognition receptor involved in the recognition of molecular structures specific for microbial pathogens,and have an important effect on innate and adaptive immune responses.There are 10 types of TLR in human beings which can be grouped into two main categories:cell surface receptors and receptors localized in the endosome.Among all the TLRs,TLR7 and TLR9,which expressed widely in human B cells,are important to B cells' functions.Two signal transduction pathways of TLR including MyD88 pathway and non-MyD88 pathway associate with B cells activation,proliferation,differentiation and antibody secretion.TLR7 and TLR9's stimulus,such as CpG-containing oligodeoxynucleotides(ODN) can activate memory B cells and naive B cells,promote cells proliferation,plasma cells generation,cytokine secretion and protect them from apoptosis.More than that,TLR7 and TLR9 can stimulate the production of IgG and IgM,make antibody shift to IgG2a and block the production of IgG1 and IgE.Interestingly,TLR-MyD88 pathway is recently confirmed to have connection with STAT3 signal pathway.However,the mutation of STAT3 will cause autosomal dominant hyper-IgE syndrome (HIES),a primary immunodeficiency characterized by elevated IgE levels,eczema,recurrent infections,pneumonia as well as multi-system symptoms.Therefore,the pathogenesis of HIES maybe related to the inhibition of TLR-MyD88-STAT3 signal pathway.As a result,we write a review about TLR in B cell activation and STAT3 signal pathway,and discuss their connection between HIES.