MOLECULAR CHARACTERIZATION OF THE V-REGION OF 4 IGE ANTIBODIES SPECIFIC FOR TRICHOSANTHIN

We report here the cDNA cloning and variable region nucleic acid seque nces of the heavy and the light chains of four monoclonal IgE and one monoclonal IgG1 antibodies against trichosanthin (TCS), all of which r ecognized a similar or related antigenic determinant. Sequence analysi s revealed that the V-H regions of the four IgE antibodies use differe nt V gene segments from the 7183, 36-60 and J558 families. The D-H gen es varied extensively in nucleotide sequence and length, with D segmen ts DSP2, DFL16 and DQ52 being used with equal frequency. All J(H) gene segments except J(H)1 were present in the epsilon transcripts. In con trast, there appeared to be restricted L-chain utilization. All four L -chain V genes cloned belonged to the V kappa 21 family and a bias in the use of J kappa 1 gene was also observed. The V-L sequences of the anti-TCS monoclonal antibodies showed much less diversity than the V-H sequences. We propose that the L-chain rather than H-chain may play a more significant role in specific binding with allergenic determinant on TCS.