Figure 1.

Equivalent inflammatory response to serum transfer arthritis. Response of Nik+/+ and Nik–/– mice to arthritogenic serum was evaluated from days 0 to 14 by clinical scoring (A) and measurement of hind paw thickness (B). Clinical scores were obtained by observation of all 4 paws, with a maximum score of 4 indicating whole-paw redness and swelling in all 4. Hind paw thickness was measured by digital gauge at the ankle, and the sum of the data for both paws was plotted. Graphs show mean ± SEM at each data point for 8 mice. There were no significant differences (P < 0.05) in either parameter between Nik+/+ and Nik–/– mice. (C) Semiquantitative RT-PCR analysis of RNA derived from hind paws at days 0, 3, and 4 shows that RANKL and TNF-α are both induced by injection of arthritogenic serum in Nik+/+ and Nik–/– animals.