Expression of neurotrophin receptors in normal and malignant B lymphocytes

In order to define a cellular model suitable for studying, in vitro, the mo lecular properties and functions of neurotrophin receptors in human lymphoc ytes, TrkA, TrkB, TrkC and p75(NTR) expression was investigated in a panel of EBV immortalized lymphoblastoid (LCL) and Burkitt lymphoma-derived cell lines (BLs) compared to primary B lymphocytes by RT-PCR and flow cytometric analysis, Our data show that trkA and trkB are transcribed in most B cell lines of normal and malignant origin, For several of them, we also gained f irst evidence of trkC expression in B cells. All cell lines and primary B c ells lack p75(NTR) expression. These data suggest that neurotrophin recepto rs expression in the B cell lines correlates to some extent with the phenot ypic maturation stage and endogenous viral activity levels, Our data sugges t that TrkA and TrkB, once activated, provide a partial rescue from apoptos is, whereas TrkC stimulates the progression through the cell cycle without affecting cell survival. Finally, the identification of a number of cell li nes showing single expression of one of the Trk receptors has disclosed the availability of a cellular tool for further studies on their function, and mechanisms of signal transduction in the B cell moiety in the absence of p 75(NTR).