BALB/c mice genetically susceptible to proteoglycan-induced arthritis and spondylitis show colony-dependent differences in disease penetrance

Table 1 Arthritis susceptibility, severity, and onset of different BALB/c colonies

Colony^a		Vendors	Arthritic/total number of animals		Arthritis score (acute)^b	Onset score^c
Number	Symbol		Incidence	Percentage
1	●	Portage P08; Charles River Laboratories, Inc. (Wilmington, MA, USA)	16/16	100%	11.0 ± 1.1	2.3 ± 0.3
2	●	Canada II; Charles River Laboratories, Inc.	15/15	100%	10.3 ± 1.3	2.5 ± 0.4
3	●	Harlan Laboratories, Inc. (Indianapolis, IN, USA)	12/13	92%	9.7 ± 1.5	2.8 ± 0.5
4	■	Kingston K72; Charles River Laboratories, Inc.	13/14	93%	8.8 ± 1.2	2.1 ± 0.4
5	■	Raleigh R02; Charles River Laboratories, Inc.	15/15	100%	7.6 ± 1.0	1.9 ± 0.3
6	■	Taconic Farms, Inc. (Hudson, NY, USA); Charles River Laboratories, Inc.	15/18	83%	7.5 ± 1.4	1.6 ± 0.3
7	■	NCI/Kingston (Charles River Laboratories, Inc.)	17/20	85%	6.8 ± 0.9	1.5 ± 0.2
8	■	BALB/cJ; The Jackson Laboratory (Bar Harbor, ME, USA)	16/19	84%	6.6 ± 1.1	2.1 ± 0.3
9	■	Raleigh R12; Charles River Laboratories, Inc.	10/13	77%	6.4 ± 1.5	1.2 ± 0.2
10	▲	Hollister H42; Charles River Laboratories, Inc.	10/15	67%	3.8 ± 0.8	1.1 ± 0.2
11	▲	Bailey's BALB/c ByJ; The Jackson Laboratory	15/20	75%	2.4 ± 0.7	1.0 ± 0.2

All animals were immunized with human cartilage proteoglycan aggrecan in dimethyldioctadecyl-ammonium bromide. Values represent mean ± standard error of the mean. ^aColony numbers indicate the different BALB/c colonies. ^bHighest arthritis score measured at any time point of the experiment. ^cOnset score was calculated at the end of the experiment (days 63 and 64) and ranged from the earliest onset of inflammation (5) to no arthritis (0). Circles (●) represent the most arthritis-prone colonies. Designation was based on the statistical analysis showing no significant differences between these three colonies (1 to 3) comparing two major clinical variables: onset and severity. Therefore, these three colonies were combined and designated as group I (Figure 1a). Squares (■) indicate the average clinical phenotype of arthritis (colonies 4 to 9) with no significant differences using onset and severity scores as clinical phenotype markers. This combined group is designated as group II (Figure 1a). Triangles (▲) represent the two least arthritic or least susceptible colonies, 10 and 11. Data of these two colonies were combined, and the two colonies together were designated as group III (Figure 1a). NCI, National Cancer Institute (Bethesda, MD, USA).

ISSN: 1478-6362