Immunogenicity of rhGH from formulation II as measured by anti-hGH antibodies in wild-type and hGH-transgenic BalbC mice
| Group | Animal | Form of rhGH | Treatment Duration (wk) | No. Mice Seroconverting on | Mean titer (day 100) | ||
|---|---|---|---|---|---|---|---|
| Day 30 | Day 51 | Day 100 | |||||
| 1 | wt | Solution | 4 | 12 /13 | 11 /12 | 6 /12 | 1.8 ± 0.7 |
| 2 | wt | Microspheres | 4 | 7 /13 | 6 /12 | 3 /13 | 1.4 ± 0.2 |
| 3 | hGH tg | Solution | 4 | 0 /12 | 0 /10 | ND | NA |
| 4 | hGH tg | Microspheres | 4 | 0 /9 | 0 /9 | ND | NA |
| 5 | wt | Solution | 12 | 9 /12 | 10 /12 | 11 /12 | 3.4 ± 1.0 |
| 6 | wt | Microspheres | 12 | 0 /13 | 11 /11 | 12 /12 | 3.7 ± 0.8 |
| 7 | hGH tg | Solution | 12 | ND | 0 /11 | 0 /8 | NA |
| 8 | hGH tg | Microspheres | 12 | ND | 0 /12 | 0 /10 | NA |
There were a total of 10 groups of BalbC mice, 5 nontransgenic (wt, wild-type) (groups 1, 2, 5, 6 and 9) and 5 rhGH transgenic (tg) groups (3, 4, 7, 8 and 10). Both transgenic and nontransgenic animals (groups 9 and 10) received no treatment and none of these animals seroconverted (data not shown). Groups 1 and 3 received a total of 12 s.c. injections of rhGH solution (10 μg/dose) delivered thrice weekly (a total dose of 120 μg protein) and groups 5 and 7 received 36 s.c. injections, thrice weekly, of protein solution for 12 wk (a total amount of 360 μg protein). Groups 2 and 4 received a single s.c. injection of microspheres formulation II (120 μg of rhGH, 800 μg microspheres) and groups 6 and 8 received three injections of the same dose of microspheres (days 0, 28, and 56) for a total dose of 360 μg rhGH (2.4 mg microspheres). Statistical analysis (using the Fisher exact test) showed that the percent mice in groups 1 and 2 seroconverting on days 30 and 51 were significantly different (P = 0.036 and 0.034, respectively) whereas the difference on day 100 was not. The difference in percent seroconversion between groups 5 and 6 on day 30 was very significant (P = 0.0001). ND; Not done. NA, not applicable.