cDNA Sequence Analysis of Monoclonal Antibodies Against the Human Placental Acidic Isoferritin

Abstract

By using human placental acidic isoferritin (PAF) as antigen to immunize BALB/c mice and conventional cell fusion, we have established three mouse hybridoma cell lines that secrete IgG monoclonal antibodies (MAbs) to PAF, termed as Z-2-3, Z-2-5, and Z-3-6, respectively. In ELISA, the MAbs were shown to react specifically with human PAF. We then applied the polymerase chain reaction (PCR) technique to clone variable region genes of the heavy (V_H) and light (V_L) chains of these MAbs, and appropriate full-length cDNA clones were obtained and characterized by nucleotide sequence analysis. V_H and V_L segments of anti-human PAF MAbs belong to the J558 and V_κ19 family, respectively. The nucleotide sequence of Z-3-6 in the V_H segment is highly homologous to that of MAb 18.1.16 except for their diversity minigenes. The light chain sequences of these MAbs show high homology with that of MAb cc92. It is implied that the D segment and the nucleotides inserted at the V_H-D and D-J splice junctions are mostly responsible for the specificity of Z-3-6, and that the differences between the V_H and V_L sequences of these MAbs may determine their different affinity or recognition of different antigenic determinants.