Defective in vitro migratory capacity of bone marrow cells from viable motheaten mice in response to normal thymus culture supernatants

"Viable motheaten" mice are severely immunodeficient and develop autoantibodies early in life. The thymus appears normal for the first 3-4 weeks, after which there is depletion of cortical thymocytes and a diminution in the size of the organ until it is atrophic. The present study utilized an in vitro migration assay, in which bone marrow cells from viable motheaten mice were found to have a greatly diminished capacity to migrate in response to normal thymus supernatant when compared to normal bone marrow cells. It was also determined that thymus supernatant prepared from newborn viable motheaten mice was chemoattractive to normal bone marrow but not to viable motheaten bone marrow. The results of in vivo reconstitution of lethally irradiated viable motheaten mice with normal bone marrow cells also show that the thymus of the mutant is normal in its ability to attract and be repopulated by normal donor bone marrow. Therefore, the premature thymic involution of viable motheaten mice is related to the inability of bone marrow cells from these mice to migrate or respond to signals from the thymus.