Receptor analysis of idiotype antibodies derived from MALT type B-celilymphoma hybridomas

Abstract

The generation of human antibodies derived from extranodal MALT type B-cell lymphomas allows to evaluate steps in their pathogenesis as well as to establish potential immunological therapies. Intraclonal diversity and the existence of bystander nonmalignant B-cells outline the need for reliable identification of the tumor immunoglobulin representing hybridomas. Human heterohybridomas were generated from five cases of MALT type B-cell lymphomas (4 low grade, one high grade) by the fusion of lymphoma B-cells with the murine myeloma cell line NSO and tested for isotype identity with the tumor. RT-PCR using VH Frl/JH primers was performed with RNA of tumors and hybridomas that share the same isotype with the tumor. PCR-products were sequenced directly. In each case lymphomas were hybridized with a comparable fusion efficiency. DNA sequence analysis of the immunoglobulin heavy chain identified one or more hybridomas derived from the tumor. However some other hybridomas which share the same isotype with the tumor, maybe different in their VH family or their sequence. Hybridomas can be used as a tool for the research on the MALT lymphoma immunoglobulin receptor. For the identification of tumor immunoglobulin, secreting hybridomas sequencing and the check of molecular identity is indispensable after isotype determination.