Nucleotide sequence of Ig variable genes of human anti-V3 mAbs was determined as previously described [60, 61] . The messenger RNA was extracted from hybridoma cell lines producing anti-V3 mAbs and reverse transcribed into cDNA using oligo dT primer. Amplification of the variable fragment was performed by PCR using different gene family-specific sets of primers and cDNA as template. were located at 5 0 end of V genes. Reverse primer [5 0 -CTTGGTGGARGCTGARGAGACGGTGACC-3 0 ] was located at the 3 0 end of JH segment and up to 12 nucleotides at the 5 0 of the constant region of IgG [69] . PCR amplification was performed using cycling program of 2 min at 94°C, 35 cycles of 60s at 94°C, 60s at 56°C, and 90s at 72°C, followed 8 min at 72°C. Ethidium bromidestained 0.8% agarose gels were used to visualize the PCR products. The bands of the appropriate size were excised and cleaned with GeneElute Minus EtBr Spin Column (Sigma, USA). PCR products were sequenced (Macrogen, South Korea) in both directions using the primers applied for amplification. The sequence data were analyzed using the International ImMunoGeneTics (IMGT) information system (http://imgt.cines.fr).