Expression of cell-surface latent allotypes: latent specificities are synthesized only by cells that display the nominal allotype.

The association of latent and nominal allotypes at the cell surface of rabbit peripheral blood lymphocytes (PBL) was studied in animals from 2 closed group colonies. The specificity of the anti-allotype antibodies used in the mixed antiglobulin rosette test was confirmed by radioimmune assay and by testing PBL from latent allotype-free homozygotes. PBL from rabbits exhibiting latent group a and b allotypes were treated with pronase to bring the rosetting population down to less than 1 to 2%; latent and nominal cell-surface allotypes were then regenerated overnight in serum-free culture. Latent and nominal allotypes were detected in the same cell in 16 to 57% of the total allotype-bearing population. The remaining cells displayed only nominal allotype. This was observed in rabbits bearing latent a1, a2, a3, b4, b5, and b6. Rosette-inhibition data indicated that some of the group a latent and nominal allotypes were contiguously associated at the cell surface but that the group b latent and nominal markers were spaced further apart. In addition, in rabbits exhibiting 2 latent group b allotypes, both single and double latent cell surface expression was seen. Rabbits from the Philadelphia and N.I.H. internally derived colonies gave similar results.