The immunomodulatory effect of juice obtained from leaves of Kalanchoe brasiliensis (Kb) on zymosan-induced inflammation was investigated. C57B110 mice received a subcutaneous injection of 150 microg zymosan in the footpad. After 7 days, there was an increase in footpad thickness from 176 +/- 4 to 236 +/- 9 x 10(-2) mm and in blood flow in the footpad area, monitored by 99mTc, from 98 +/- 4 to 694 +/- 59 counts per minute (cpm). Zymosan induced a severe infiltration of leukocytes into the articular tissues and a 13-fold increase in the adjacent popliteal lymph node (PLN) weight. Beginning 2 days after the injection, mice were treated daily for 5 days with different concentrations of lyophilised Kb juice dissolved in water. Treatment with 480 mg/kg/day reduced footpad thickness to 193 +/- 5 x 10(-2) mm, leukocyte infiltration and blood flow to 150 +/- 18 cpm in the footpad area. PLN weight in zymosan-injected mice decreased from 6.5 +/- 0.5 to 1.5 +/- 0.4 mg, similarly to the decrease after treatment with indomethacin (3 mg/kg/day). Flow cytometric analysis of lymph node cells showed an important reduction in B cell number in Kb-treated mice. Treatment over a period of 10 days was also effective at reducing zymosan-induced inflammation, even when started 7 days after injection. These data suggest anti-inflammatory and immunosuppressive effects of K. brasiliensis that may account for its popularity in folk medicine against rheumatic diseases.