Monoclonal anti-VH141 antibodies that specifically recognize the heavy chain variable region of, and are closely related to, MOPC141 myeloma protein whose VH gene belongs to VHQ52 family

To raise monoclonal antibodies that specifically recognize the heavy chain variable region of MOPC141 myeloma protein (VH141), which belongs to VHQ52 family, rats were immunized with Fd'-conjugated keyhole limpet haemocyanin (KLH) (Fd': Fd' fragments of MOPC141), and the spleen cells were fused with mouse myeloma cells. The resulting 900 hybridomas were screened for antibody activity against Fd'1 fragments having no constant H-chain sequences, which were prepared by cleavage of the Fd' fragments with cyanogen bromide, and two monoclonal antibodies, designated 3-2-7h and 3-5-6f, were obtained. Radioimmunoassay inhibition test showed that the two monoclonal antibodies specifically recognized the VH141, but each was directed to a different determinant on the VH141. When the functional VH gene of Abelson virus-transformed mu-producing pre-B cells, which could be strongly stained with 3-5-6f monoclonal antibody, was cloned and sequenced, the VH gene was closely relate to that of MOPC141 (88% and 94% homology at amino acid and DNA level, respectively). Taken together, the results indicated that 3-2-7h had high specificity only for the VH141, whereas 3-5-6f specifically reacted not only with the VH141 but also with the VH region closely related to that of MOPC141, and that both the monoclonal anti-VH141 antibodies were specific for a limited range of VH regions within the VHQ52 family rather than being VHQ52 family specific. These monoclonal anti-VH141 antibodies should be very useful to determine at a single cell level by immunofluorescence the usage of the VH gene(s) identical or closely related to that of MOPC141 during early B-cell development.