Summary of KIT mutants and frequency of conferring IL-3–independent growth to FDC-P1 cells
Vector/KIT mutant . | Frequency of IL-3–independent growth . |
|---|---|
| Control vector (YFP alone) | < 6.3 × 10-8 |
| Wild-type hKIT | |
| With SCF | 1.8 × 10-3 |
| Without SCF | < 6.3 × 10-8 |
| Extracellular | |
| mT417Δ, Y418Δ, D419Δ InsV (exon 8) | 1.1 × 10-4 |
| hD419A | 8.2 × 10-5 |
| Transmembrane | |
| hV530I | > 7.0 × 10-6 |
| Juxtamembrane | |
| mV558D | 1.6 × 10-2 |
| Tyrosine kinase domain II | |
| mD814V | 7.3 × 10-3 |
| hD816V | 6.2 × 10-3 |
Vector/KIT mutant . | Frequency of IL-3–independent growth . |
|---|---|
| Control vector (YFP alone) | < 6.3 × 10-8 |
| Wild-type hKIT | |
| With SCF | 1.8 × 10-3 |
| Without SCF | < 6.3 × 10-8 |
| Extracellular | |
| mT417Δ, Y418Δ, D419Δ InsV (exon 8) | 1.1 × 10-4 |
| hD419A | 8.2 × 10-5 |
| Transmembrane | |
| hV530I | > 7.0 × 10-6 |
| Juxtamembrane | |
| mV558D | 1.6 × 10-2 |
| Tyrosine kinase domain II | |
| mD814V | 7.3 × 10-3 |
| hD816V | 6.2 × 10-3 |
The frequency of IL-3–independent growth was calculated by end-point dilution of infected cells plated in the absence of IL-3 and by applying the Poisson distribution.15 The frequency was corrected for the plating efficiency in IL-3 for each culture (between 42% and 96%). In 2 independent experiments, in which 107 cells were plated in the absence of IL-3, no factor-independent growth was observed in FDC-P1 cells expressing the control vector or wild-type hKIT. The frequency of obtaining cell growth in hSCF (100 ng/mL) was determined in FDC-P1 cells infected with the wild-type hKIT vector. The exact incidence of factor-independent growth was not determined for mutant V530I, but is between 7 × 10-6 and 5 × 10-5. SCF indicates stem cell factor.