Fusion of ascidPre-B Cell with a Wild Type (Myeloma) B Cell Results in Correct Rearrangement of a V(D)J Recombination Substrate

Mice with the scid mutation have a defect in the V(D)J recombinase. In order to determine whether the SCID product is normally present in mature B cells that do not have the recombinase activity, scid pre-B cells were fused with myeloma cells. It was found that in the hybrid cells, a rearrangement test gene was correctly joined immediately after fusion. The same test gene was aberrantly rearranged in the scid pre-B cells. Stable hybrids between the scid pre-B and the myeloma cells had lost the expression of RAG-1 and RAG-2 genes, supporting the previous finding of an inhibitor of rearrangement in myeloma cells that acts shortly after fusion. Thus, mature B cells apparently contain the SCID product, the wild type SCID function is not competitively interfered with by products present in scid pre-B cells, and the SCID product seems not to be a target for the recombinase inhibitor.