Rabbit-mouse hybridomas secreting intact rabbit immunoglobulin.

Rabbit-mouse hybridomas offer the potential for production of monoclonal rabbit antibodies by immortal cell lines. In previous studies, it was possible to produce and stabilize rabbit-mouse hybrid cells secreting either a rabbit heavy or light chain. These have been useful for structural characterization of the individual rabbit immunoglobulin polypeptides and for isolation of large amounts of immunoglobulin mRNA for molecular studies. For some studies, however, it would be useful to have intact rabbit immunoglobulin molecules comparable to the myeloma proteins available in the human and mouse. The availability of rapid, sensitive and specific assays for rabbit heavy and light chains and allotypes located on specific chains has now permitted the early identification of clones secreting intact rabbit immunoglobulin. Vigorous cloning efforts have resulted in isolation and partial stabilization of three such clones. The first, H105, secretes a product with a kappa light chain bearing the b6 allotype and a mu-chain bearing the a1 allotype. Biochemical and serologic analyses of the product show that it is secreted as a fully assembled IgM pentamer and that the rabbit heavy and light chains are covalently associated. No rabbit J-chain gene was detected in H105 by Southern blot analysis. The second hydridoma, H134, secretes a product with a mol. wt of 150 K, consisting of a b4 light chain and an a1 heavy chain. The third, H171, secretes an alb4 IgG with antibody specificity for group C streptococcal carbohydrate. An additional rabbit-mouse hybridoma, H89, have been produced which secretes a rabbit heavy chain lacking group a allotypic activity. The rabbit heavy chain, which is associated with a mouse light chain, has an N-terminal amino acid sequence identical to a2-positive molecules although thorough serologic analysis revealed no group a allotypic activity.