Antigen-Specific Monoclonal Antibodies Isolated from B Cells Expressing Constitutively Active STAT5

<div><h3>Background</h3><p>Fully human monoclonal antibodies directed against specific pathogens have a high therapeutic potential, but are difficult to generate.</p> <h3>Methodology/Principal Findings</h3><p>Memory B cells were immortalized by expressing an inducible active mutant of the transcription factor Signal Transducer and Activator of Transcription 5 (STAT5). Active STAT5 inhibits the differentiation of B cells while increasing their replicative life span. We obtained cloned B cell lines, which produced antibodies in the presence of interleukin 21 after turning off STAT5. We used this method to obtain monoclonal antibodies against the model antigen tetanus toxin.</p> <h3>Conclusions/Significance</h3><p>Here we describe a novel and relatively simple method of immortalizing antigen-specific human B cells for isolation of human monoclonal antibodies. These results show that STAT5 overexpression can be employed to isolate antigen specific antibodies from human memory B cells.</p> </div>