Nucleotide sequence analysis of a human monoclonal antibody 22-13 reactive with lung tumor-associated antigen.

A human monoclonal antibody (HuMAb) 22-13 (IgG1, kappa) recognizes a cytoplasmic antigen associated primarily with human lung tumors. This study reports the primary nucleotide and deduced amino acid sequences of the rearranged heavy and light chains of the HuMAb 22-13. This HuMAb uses a VH gene member of the V(H)Ia gene family, 51P1 and is productively rearranged with a D-D fusion product of the D(LR)2 and D(XP)2 germ line DH genes and the germ line JH3 gene. HuMAb 22-13 Vkappa belongs to the kappa light chain variable subgroup IIIb family and appears to be derived from the Humkv325 germ line gene and is rearranged with a germ line Jkappa5 gene. The results reveal that production of a HuMAb 22-13 is achieved by rearrangement of the 51P1/Humkv325 germ line variable region gene combination, associated with the autoimmune repertoire and that HuMAb 22-13 has a striking sequence homology to rheumatoid factors (RFs) of the Wa idiotypic family. HuMAb 22-13 and Wa RFs have in common V(H)Ia and VkappaIIIb gene segments, but use different DH, JH and Jkappa gene segments. However, in spite of this structural similarity, HuMAb 22-13 does not display rheumatoid factor activity. Taken together with the reported findings, these data indicate the representation of the shared usage of highly homologous variable region genes in entirely different humoral immune responses in the human system.