Rearrangements of T cell receptor loci can be found only rarely in B lymphoid cells.

We have studied the rearrangement status of the T cell receptor genes in 64 B lymphoid cell lines, and we found that, unlike the immunoglobulin heavy chain genes in T lymphocytes, T cell receptor beta and related gamma chain genes are almost always in germ-line configuration in B lymphoid cells. The only exception was a myeloma MOPC511 (IgA, chi) which contained all T cell receptor genes, beta 1, beta 2, gamma 1, gamma 2, gamma 3 and alpha, in rearranged configuration in both homologous chromosomes. This exception supports the concept that all immunoglobulin and T cell receptor genes exploit the same recombinase to build their complete variable regions. Obviously, in MOPC511 cells the regulation, which confers the tissue specificity i.e. T vs. B lymphocytes, has failed.