Figure 6

MBP-induced allodynia is T cell-dependent. (A) von Frey testing for mechanical allodynia in athymic nude (rnu^−/−) and wild-type heterozygous (rnu^+/−) rats after the MBP84-104 injection (50 μg in 5 μL) into the naïve sciatic nerve. The mean withdrawal thresholds (gram force, g) ± SEM of n = 6/group decline rapidly after the MBP84-104 injection into normal rats, corresponding to allodynia (arrow), but remain significantly higher in nude rats (**, P < 0.01; *, P < 0.05). (B) Hargreaves testing for thermal sensitivity. The mean paw withdrawal latency ± SEM of n = 6/group after thermal stimulation (radiant heat) before (baseline) and at the indicated days after the MBP84-104 injection were not different between the groups. (C) Spontaneous pain scoring of the MBP84-104 injected paw positioning for 6 min (3 x 120 s) using a 0–5 numerical scale demonstrates the absence of spontaneous pain-like behaviors in both rat types. The mean score ± SEM of n = 6/group.