The antigen receptor of the MALT lymphoma cells provides crucial information, which may help to elucidate the pathogenesis of that tumor. Therefore hybridomas were produced from five MALT type lymphomas. The identity was proven by sequencing the VH chain of the tumor and the hybridomas. It could be shown the one step of subcloning and limiting dilution is necessary to obtain a monoclonal hybridoma in most cases. So it is indispensable to check the identity of the tumor antibody and the hybridoma antibody for each hybridoma. Otherwise it may be possible that bystander cells infiltrating the tumor, but not belonging to the malignant clone, get fused. Furthermore we provide evidence of an intra tumoral diversity within the MALT type lymphoma that was reflected by the different mutation pattern of the tumor derived hybridomas. Therefore the hybridomas are allowing investigation on the protein level about the hypermutation of the genes of the MALT lymphoma antibodies and the possible role antigenic selection within the tumor.
