Effects of Yunke (technetium-99 conjugated with methylene diphosphonate; (99)Tc-MDP) and/or colloidal chromic phosphate phosphonium-32, alone and in combination, in rats with adjuvant arthritis.

1. The present study investigated the therapeutic effects of both single and combination treatment with Yunke (technetium-99 conjugated with methylene diphosphonate; (99)Tc-MDP) and colloidal chromic phosphate (32)P (phosphonium-32) in rats with adjuvant arthritis (AA). 2. Rats were randomly allocated to one of five groups: (i) normal control group (sham operated and treated with normal saline); (ii) AA control group (arthritis induced with adjuvant and treated with normal saline); (iii) (32)P colloid group (arthritis induced with adjuvant and treated with a single intra-articular injection of colloidal chromic phosphate phosphonium-32 (0.02 mCi) and i.p. injections of normal saline every other day); (iv) Yunke group (arthritis induced with adjuvant and treated with i.p. Yunke (2.5 x 10(-3) microg/kg) every other day and single intra-articular injection of normal saline); and (v) combination group (arthritis induced with adjuvant and treated with a combination of both therapies). 3. The left-to-right diameter (LRD) of the left hind ankle, serum levels of tumour necrosis factor (TNF) and interleukin (IL)-1b and histological sections of the ankle joints were examined at different time points. 4. The LRD of the left hind ankle was smaller for the combination group compared with (32)P colloid alone at Week 4 (7.11 +/- 0.28 vs 7.57 +/- 0.24 mm, respectively; P < 0.001). The combination treatment was more effective than (32)P colloid alone in decreasing serum TNF (1.614 +/- 0.368 vs 1.977 +/- 0.255 ng/mL, respectively; P = 0.002 for Week 4) and IL-1b (0.271 +/- 0.027 vs 0.308 +/- 0.020 ng/mL, respectively for Week 4; 0.209 +/- 0.023 vs 0.255 +/- 0.016 ng/mL, respectively for Week 6; both P = 0.001). Histologically, the combination group exhibited less synovium proliferation compared with Yunke treatment alone and decreased inflammatory cell infiltration compared with (32)P colloid alone. 5. In conclusion, the combination of Yunke and (32)P colloid is more effective in the treatment of AA in rats compared with Yunke or (32)P colloid alone.