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