Th1/Th2 cytokine expression and its relationship with tumor growth in B cell non-Hodgkin's lymphoma (NHL)

A T helper 1 (Th1) immune response is considered more effective than T helper 2 (Th2) for anti-tumor immunity, but either response could potentially stimulate tumor cell growth in lymphomas. Moreover, both IL-4 and IL-2/IL-12 are used in experimental treatment models for non-Hodgkin's lymphoma (NHL) despite their differing ability to elicit Th2 or Th1 responses, respectively. Here, we investigate which T helper cytokines (Th1 or Th2) predominate in B cell NHL tissue and determine whether cytokine expression correlates with tumor cell growth, cell death, and survival in a series of 44 NHL patients. Overall, we observed both Th1 and Th2 cytokine expression at the mRNA level, detecting high levels of IFNγ, IL6 and IL-10 expression in the majority of tumors. Transcripts for the IL-12 subunits p35 (38 of 38) and p 40 (23 of 38) were frequently detected in NHL tissue, and high p40 levels were common in patients with a good prognosis. Furthermore, high IL-4 levels correlated with greater survival duration (P < 0.0024) but nor overall survival. Cytokine expression of IL-2, IFNγ and IL-4 was significantly reduced in the high grade tumor group. Interestingly, there was a strong correlation between high IL-4 levels and reduced levels of apoptosis (P < 0.006) or proliferation (P < 0.0001), which has also been reported in leukemic models. This has important implications for the success of IL-4 as a treatment for low and high grade tumors.