Table 2. Immunological activity of fraction ΔlytB #20*.
| Dilution factor | CD69 expression (% Vγ9+ CD3+)† | Bioactivity (mm IPP)‡ |
|---|---|---|
| Medium control | 29·8±8·4 | – |
| 6·25×107 | 29·9±12·4 | – |
| 1·25×107 | 35·1±7·0 | 3759·5 |
| 2·5×106 | 40·4±1·4 | 1823·8 |
| 5·0×105 | 52·2±0·2 | 2592·5 |
| 1·0×105 | 63·0±1·3 | 3104·2 |
| 2·0×104 | 66·2±0·6 | 1065·9 |
| Mean±SEM§ | – | 2469·2±472·7 |
A calibration curve was obtained using serial dilutions of an isopentenyl pyrophosphate (IPP) standard, ranging from 80 nm to 10 µm and yielding the formula (at R2=0·99): Bioactivity (µm IPP)=0·000869×e0·167×(CD69 expression level).
Upregulation of CD69 expression was monitored after incubation of peripheral blood mononuclear cells for 18 hr in the presence of serial dilutions of fraction ΔlytB #20 (n=3).
Bioactivity of fraction ΔlytB #20 was calculated for each dilution using the formula: Bioactivity ΔlytB #20 (mm IPP)=(1/1000×[bioactivity (µm IPP)×dilution factor]).
Mean bioactivity from the five dilutions tested that resulted in upregulation of CD69 expression above the background value. An analogous experiment measuring γδ T-cell expansion after 6 days resulted in a bioactivity value of 2487·6±911·4 mm IPP.
SEM, standard error of the mean.