The major findings of our study may be summarized as follows: (a) human CRCs harbor B cells (i.e. TiBc) that can be long-term cultured subsequent to EBV-immortalization; (b) TiBc harvested from these are antigen-experienced and secrete Ig of the three main Ig isotypes (IgG, IgA, IgM) in amounts sufficient for functional studies; (c) IgG derived from several TiBc clones strongly bind to antigenic structures present on several allogeneic tumor cell lines; and (d) TiBc show no evidence for latent EBV-infection in vivo. Here, CD79A is linked to Epstein-Barr virus infection.