ExprEssion of CD40 anD CD40L by DiffErEnt tumor CELLs

CD40 — a type I glycosilated phosphoglycoprotein with the molecular weight of 48 kDa — belongs to the superfamily of type I TNF receptors. This molecule was firstly identified on normal and transformed B-lymphocytes, and also on the cells of bladder tumor as early as at 80th of last century [1, ]. The discovery of CD40 molecules on normal B-lymphocytes has encouraged the researches aimed on the estimation of their role in immunologic response that began after identification of the ligand for this molecule on T-lymphocytes — CD40L (CD154). As a result, it has been shown that CD40 and CD40L play a key role in intercellular interactions of the abovementioned two main populations of cells of immune system [3]. Later it has been revealed that CD40 is expressed also by a number of antigen-presenting cells (dendritic cells, monocytes, macrophages) eosinophils, basophils and also by keratinocytes, epithelial, neural and other types of cells, and its expression possesses pronounced costimulatory properties [4–6]. The structure of CD40 includes extracellular, transmembrane and intracellular parts. The patterns of CD40 structure allow to suppose that the molecule can act as a trimeric receptor able to activate different messengers, and its functional activity is manifested at the highest degree when CD40 acts as a trimeric receptor complex. The structure of CD40 molecule is presented on the Figure [5]. This information finally allows to determine CD40 as a structure playing an important role in different forms of immunologic response, because it is taking part in activation, proliferation, differentiation of different types of cells of immune system [5, 7–9].