Induction of local and systemic IL-6 by PDT. Samples were collected from control animals (no treatment, HPPH alone) at 6 h ‘post-PDT’. The total amount of protein per tumour was determined using the Bio-Rad protein assay. (A) IL-6 levels were determined by ELISA and are reported as either pg μg⁻¹ of total protein (tumour) or pg ml⁻¹ serum. A minimum of three mice were analysed at each time point. Error bars represent the s.e. Tumour IL-6 👁 Image
; serum IL-6 👁 Image
. (B) EMT6 tumour-bearing mice were subjected to HPPH treatment. At 0 h, one group of five mice was exposed to light (135 J cm⁻²) (filled symbols), and another group of five mice was kept in the dark (control, open symbols). Every 24 h, a blood sample was collected for each mouse and the serum level of HP was determined by immunoelectrophoresis. The values were calculated in mg ml⁻¹ and the HP concentration for each mouse and bleeding was reproduced.