TABLE 1.

Attenuation of arthritis, but not carditis, by passive transfer of immune mouse serum into B. burgdorferi- infected B10.A^k-Igh-6^tm1Cgn mice^a

Panel and mouse group	Mean arthritis severity ± SDb	Carditis prevalence (no. of animals affected/total no. of animals)	Mean no. of spirochetes/μg of tissue ± SDc
Panel A
B10.Ak-Igh-6tm1Cgn	1.9 ± 0.6	6/6	ND
B10.Ak-Igh-6tm1Cgn	2.6 ± 0.4	0/7	ND
Panel B
B10.Ak + NMS	0	9/9	3 ± 1
B10.Ak-Igh-6tm1Cgn + NMS	1.2 ± 0.6	9/9	>25
B10.Ak-Igh-6tm1Cgn + IMS	0.5 ± 0.1d	11/11e	4 ± 0

^aResults are representative of two separate passive immunization experiments. 

^bValues reported are the mean of tibiotarsal joint scores from individual mice for each group, as assessed on a scale of 0 to 3. 

^cValues were rounded to the nearest integer; values equivalent to >25 spirochetes were above the cutoff for enumeration. ND, not determined. 

^dSignificantly different (P < 0.05, Fisher exact test) from value for B10.A^k-Igh-6^tm1Cgn mice treated with NMS. 

^eCarditis in this group was equivalent in severity to that observed in B10.A^k mice and B10.A^k-Igh-6^tm1Cgn + NMS.