INTERLEUKIN (IL)-10 AND IL-6 ARE PRODUCED IN-VIVO BY NON-HODGKINS-LYMPHOMA CELLS AND ACT AS COOPERATIVE GROWTH-FACTORS

The in vivo production of interleukin (IL)-10, IL-6, IL-2, and tumor n ecrosis factor (TNF)-alpha in tumor samples was investigated by immuno histochemistry in 54 non-Hodgkin's lymphomas (NHLs). Respectively, 55, 89, 23, and 29% of tumor samples were found positive for IL-10, IL-6, IL-2, and TNF-alpha expression by immunohistochemistry. Using reverse transcription-PCR, the mRNA of IL-10 and IL-6 were detectable in all samples tested and in 90 and 34% of the samples for TNF-alpha and IL-2 , respectively. In 13 patients, fresh tumor tissue was available for B NHL cell purification with Dynabeads. IL-10, IL-6, IL-2, and TNF-alph a were detectable in the supernatant of 38; 100, 0, and 23% of purifie d tumor cell preparations (PTCPs), respectively. All patients,vith det ectable IL-10 in culture had increased serum IL-10. IL-6 production by tumor cells and serum IL-6 levels were also found to be highly correl ated (P < 0.0001). This suggests that tumor cells are rt major source of serum IL-10 and IL-6 in these patients. Exogenous IL-10, IL-6, IL-2 , and TNF-alpha significantly enhanced the [H-3]thymidine uptake in 13 of 13 (100%), 5 of 13 (38%), 9 of 13 (69%), and 2 of 10 (20%) PTCPs c ostimulated with anti-CD40, respectively. IL-2, IL-6, and TNF-alpha sy nergized with IL-10 in 54, 23, and 30% of PTCPs. The combination of IL -10, IL-2, and IL-6 induced the maximal level of proliferation in 12 ( 92%) of 13 PTCPs. CD40 ligand mRNA expression was also detectable iii vivo using reverse transcription-PCR in 28 of the 29 (97%) tumor sampl es tested, including 11 of those tested for [H-3]thymidine incorporati on. These results show that IL-10, IL-6, IL-2, and TNF-alpha are produ ced in NHL tumors and may cooperate in vivo to increase NHL cell proli feration.