Table 1.
Thymic Export in Mice with Reduced Thymus Function
| Recent thymus migrants (×104) | ||
|---|---|---|
| Fraction of competent C57Bl6 Ly5 BM cells injected | CD4+ | CD8+ |
| 100% | 9.6 | 3.9 |
| 9.0 | 2.6 | |
| 8.6 | 4.9 | |
| 8.0 | 3.0 | |
| 6.5 | 2.5 | |
| 4.1 | 2.0 | |
| 4.9 | 2.7 | |
| 10% | 3.2 | 1.1 |
| 2.2 | 0.5 | |
| 1.2 | 0.4 | |
| 1.8 | 1.4 | |
| 1.4 | 0.8 | |
| 3.8 | 1.3 | |
| 2.3 | 0.9 | |
Thymus cell export varies according to the fraction of competent precursor cells. Rag2−/−B6 mice were lethally irradiated and reconstituted with BM cells from normal B6.Ly5a donors alone (100%) or from normal B6.Ly5a (10%) and T cell–deficient B6.TCRα−/−Ly5b (90%) mice. In these chimeras, the number of SP cells was proportional to the fraction of competent BM cells injected. Thymus export was evaluated 24 h after intrathymus injection of FITC.