Immune proteins and cytokine concentrations and activity were measured in skin tissue fluid-lymph and blood serum of patients with lower leg filarial lymphedema. High levels of lymph gamma-globulins, alpha-1-acid glycoprotein and IgG lymph/serum ratio were found. Lymph from filarial patients had an elevated lymph stimulatory effect on blood mononuclear cell culture with phytohemagglutinin. There was also a high concentration and activity of IL-1 beta but gamma-interferon was not detected. The deranged pattern of immune proteins and high activity of IL-1 suggest persistence of an ongoing local inflammatory process despite the absence of overt dermatitis. The high tissue-lymph IL-1 concentration and activity may signify a cytokine network promoting keratinocyte and fibroblast proliferation commonly seen on skin histology in patients with filariasis.