Induction of T-cell differentiation in the Bursa of Fabricius by a soluble thymus factor.

Bursal lymphocytes from White Leghorn chickens of different ages were incubated with a soluble thymus factor (STF), and tested for t-cell characteristics. Immunofluorescence staining with anti-T-cell serum showed a marked increase inthe percentage of bursal T lymphocytes in cell preparations from young chickensincubated with STF. In older chickens (17 weeks) no such effect was observed. Bursal cells treated with STF were also able to elicit splenomegaly showing thatnot only antigenic but also functional T-cell characteristics had been induced in apopulation of bursal cells. The fate of these bursal T-cell precursors is discussed in the context of known migratory patterns.