PRDM1, an 88kD novel transcription repressor protein is a human homolog of mouse Blimp1. It belongs to the family of PRDM protein family and contains a PR domain and 5 Kruppel Like-zinc finger motifs at the C-terminal region. It plays a pivotal role in inducing and regulating terminal differentiation of B-lymphocytes. It recruits HDAC and complex of Groucho/TLE family proteins to the DNA and actively represses vital genes required for B-cell proliferation including c-myc, CIITA promoter III, CD23b and PAX-5 promoter. PRDM1 silences IFNâ-gene expression by binding specifically to PRDI of the IFNâ gene promoter. It is continuously expressed in all Plasma cells, but is not detected in early bone marrow B-cells, memory B-cells in spleen and most germinal center B-cells. In myeloma cells, PRDI-BF1â, a truncated isoform of PRDM1 is expressed that has an impaired ability to repress transcription suggesting a clinical implication.