The relevance of peripheral blood T‐helper 1 and 2 cytokine pattern in the evaluation of patients with mycosis fungoides and Sézary syndrome

Summary Background  There is evidence that a T‐helper (Th) 2 cytokine pattern dominates in the peripheral blood as well as in tissue of patients with Sézary syndrome (SS), and that the malignant clone is of Th2 phenotype. However, there are conflicting studies on the cytokine pattern in the peripheral blood in different stages of cutaneous T‐cell lymphoma (CTCL). Objectives  To examine, by means of flow cytometry (FC), the Th1/Th2 cytokine profile [cytoplasmic interferon (IFN)‐γ/interleukin (IL)‐4] in peripheral blood T cells from patients with mycosis fungoides (MF) and SS, the most common forms of CTCL, and to correlate their expression with clinical stage, clonality and T‐cell immunophenotype changes in order to evaluate their relevance in CTCL progression. Methods  We investigated by FC the percentage of CD3+ T cells expressing cytoplasmic IFN‐γ and IL‐4 after stimulation in blood specimens of 43 CTCL patients (32 stage I–II and 11 stage III–IV), eight of whom were erythrodermic. Next, we compared cytoplasmic IFN‐γ and IL‐4 expression between patients of different stages and controls, and correlated our findings to T‐cell receptor (TCR)‐γ gene rearrangement, used as a marker of clonality, and changes in T‐cell immunophenotype (CD4+, CD8+, CD4+/CD7–, CD4+/CD25+) and natural killer cells. Polymerase chain reaction amplification of the TCR‐γ gene was performed in 41 blood and 26 skin specimens. We also examined the cytokine expression pattern in patients with erythrodermic MF and SS. Results  A significantly higher frequency of CD3+/IL‐4+ T cells was found in late (III–IV) compared with early (I–II) CTCL patients ( P  = 0·002) or controls ( P  < 0·001). There were significant positive correlations between the percentages of CD3+/IL‐4+ and the percentages of CD3+/CD4+ T cells ( r  = 0·385, P  = 0·05), CD4+/CD7– T cells ( r  = 0·335, P  < 0·05) and CD4+/CD25+ T cells ( r  = 0·433, P  = 0·01); there was a negative correlation between the percentages of CD3+/IL‐4+ and CD3+/CD8+ T cells ( r  = −0·463, P  = 0·005) and a positive correlation between the percentages of CD3+/IFN‐γ+ and CD3+/CD8+ T cells ( r  = 0·368, P  = 0·02). Increased percentages of CD3+/IL‐4+, CD3+/CD4+ and CD4+/CD7– T lymphocytes were associated with the presence of clonality ( P  = 0·025, P  < 0·001 and P  = 0·0031, respectively). All independent variables showed a statistically significant difference between SS and erythrodermic MF patients, or controls, apart from cytoplasmic IL‐4, which was high both in erythrodermic MF and SS patients compared with controls ( P  = 0·003 and P  = 0·008, respectively). In multiple regression logistic analysis, the probability of belonging to advanced CTCL stages was associated only with increased cytoplasmic IL‐4 ( P  = 0·007, odds ratio 1·13, 95% confidence interval 1·033–1·229). Conclusions  Increased T‐cell cytoplasmic IL‐4 is more frequent in late CTCL stages, correlates with T‐cell immunophenotype changes found in advanced disease and is associated with clonality. Increased cytoplasmic IL‐4 is frequent both in erythrodermic MF and SS patients, in contrast to other variables found increased only in SS, suggesting that IL‐4 may be an early indicator of disease progression. Moreover, our results show that increased cytoplasmic IL‐4 is the sole predictor of advanced CTCL disease and confirm the relevance of FC determination of IL‐4 in the routine evaluation of CTCL cases.