Table 1.

SAP IC50 values for the inhibition of fibrocyte differentiation in human and murine cell cultures.

Cells	Mouse SAP IC50 μg/ml	Human SAP IC50 μg/ml
Human PBMC	0.78 ± 0.15	0.41 ± 0.05*
Murine PBMC	7.1 ± 1.0	1.6 ± 0.1**
Murine Spleen	9.0 ± 2.1	1.3 ± 0.3**
Murine Spleen + Cytokines	15 ± 3.7	1.9 ± 0.3**

Human PBMCs, murine PBMCs, and murine spleen cells were cultured for 5 days at 5 × 10⁴ cells per well, 2.5 × 10⁵ cells per well, and 3.5 × 10⁵ cells per well, respectively, in the presence of human and murine SAP. Murine spleen cells were also cultured in the presence or absence of the cytokines IL-13 and M-CSF. Cells were air dried, fixed, stained, and enumerated by morphology. Using fibrocyte counts normalized to SFM controls, IC₅₀ levels were calculated by fitting SAP bioactivity to a sigmoidal dose response curve with variable slope. Results are expressed as mean ± SEM (n=5 for spleens, n=3 for mouse PBMCs, n=6 for human PBMCs). For the inhibition of fibrocyte differentiation by murine SAP, no significant difference was observed between the IC50 values for murine PBMCs and murine spleen cells (1-way ANOVA, Tukey’s test). Human SAP was significantly more effective than murine SAP on both human cells (p<0.05) and mouse cells (p<0.01; t-test).

^*p < 0.05;

^**p < 0.01.