TABLE 1.
Effect of Intravenous Injection of Different Human CRP Preparations on Acute Phase Proteins in Mice
| Control buffer only |
Natural CRP (n = 8) |
Bacterial recombinant CRP (n = 7) |
Dialyzed bacterial recombinant CRP (n = 8) |
P value | |
|---|---|---|---|---|---|
| Median (range) serum concentrations (mg/L) | |||||
| CRP at 24 hours | Not detected (n = 7) | 3.22 (2.16, 3.98) | 2.78 (1.74, 3.22) | 2.56 (1.76, 4.40) | 0.39 (excluding control group) |
| SAA at baseline | 12.9 (12.5, 16.9) | 14.0 (11.0, 16.0) | 16.6 (11.8, 20.2) | 22.3 (16.8, 32.2) | 0.0009 * |
| SAA at 24 hours | 12.2 (7.3, 15.3) | 10.6 (7.1, 22.5) | 460.0 (319.2, 847.1) | 410.8 (248.4, 741.2) | 0.0001 |
| Difference in SAA | −2.0 (−7.9, 2.7) | −2.3 (−8.4, 11.2) | 443.7 (301.3, 830.5) | 391.4 (223.7, 709.0) | 0.0001 |
| (24 hours - baseline) | (n = 6) | ||||
| SAP at baseline | 7.4 (6.6, 11.3) | 7.05 (5.6, 8.3) | 6.8 (5.0, 11.7) | 8.15 (6.0, 11.9) | 0.13 |
| SAP at 24 hours | 4.8 (4.2, 12.8) | 4.4 (2.3, 11.6) | 14.2 (13.1, 19.3) | 17.35 (12.5, 23.4) | 0.0001 |
| Difference in SAP | −2.5 (−7.1, 5.4) | −2.55 (−3.7, 3.3) | 7.8 (2.5, 10.3) | 9.35 (3.0, 13.6) | 0.0003 |
| (24 hours - baseline) | (n = 7) | ||||
| C3 at baseline | 513 (457, 651) | 410 (292, 504) | 499 (355, 621) | 471 (443, 626) | 0.05 + |
| C3 at 24 hours | 611 (448, 778) | 343 (319, 494) | 523 (436, 576) | 471 (337, 669) | 0.002 + |
| Difference in C3 | 45 (−99, 321) | −65 (−145, 41) | 15 (−121, 192) | −34 (−214, 149) | 0.12 |
| (24 hours - baseline) | |||||
Preparations containing 100 μg of the different human CRP preparations shown, in solution in Tris-buffered saline containing calcium, or this buffer only as a control, were injected intravenously into each mouse 48 hours after bleeding for baseline values. After 24 hours each animal was bled for assay of human CRP and murine SAP and SAA. The residual concentrations of human CRP were as expected for the ∼4 hour plasma half life of human CRP in mice.52
P values by Kruskal-Wallis test.
Although the baseline SAA values were significantly different between the groups, the absolute difference was trivial and they were all within the normal range for SAA in these mice. No sample was available for SAA assay from one mouse in the undialyzed recombinant CRP group which therefore comprised 6 animals for this analyte.
Baseline and 24 hour C3 values differed between groups but no treatment produced a significant positive or negative acute phase response.