A case is presented of an adult with Henoch Schonlein purpura (HSP) with widespread bullous skin lesions in whom serum and bullous fluid (BF) cytokines and complement proteins were analysed. In both serum and BF the total haemolytic complement was subnormal. Soluble CD25 (sCD25), which is important in B cell activation and proliferation, was over 13 times higher in the BF compared with serum. The serum and BF levels of interleukin (IL) 1, IL6, IL10, tumour necrosis factor alpha and interferon gamma were within the normal serum range of 30 healthy control subjects simultaneously analysed. The raised levels of sCD23 in BF suggest dysregulated humoral immunity in the cutaneous lesions of HSP.