Objective. To analyze the Th1/Th2 balance of peripheral Th cells in patients with systemic lupus erythematosus (SLE).Methods. The Th1:Th2 ratio was analyzed in 3 groups: SLE without proteinuria (group I; n ‫؍‬ 23), SLE with proteinuria (group II; n ‫؍‬ 31), and normal controls (group III; n ‫؍‬ 24). Group II patients who had undergone renal biopsy were classified into 3 subgroups based on their renal histopathologic findings. The intracellular cytokine detection method with flow cytometry was used to quantitate Th1 and Th2 cells.Results. There was no difference in the mean Th1:Th2 ratio between SLE patients (groups I and II) and healthy controls (group III). However, the mean value in group II was significantly higher than those in groups I and III. Moreover, within group II, the mean value in SLE patients who had diffuse proliferative lupus nephritis (World Health Organization class IV) was especially high.Conclusion. Although SLE has been considered to be a disease in which Th2 cells predominate, the Th1/Th2 balance of peripheral Th cells in SLE patients in the present study did not show a predominance of these cells. In contrast, among SLE patients with WHO class IV lupus nephritis, there was a strong predominance of Th1.

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IL-15, a T cell growth factor, has been linked to exacerbating autoimmune diseases and allograft rejection. To test the hypothesis that IL-15-deficient (IL-15-/-) mice would be protected from T cell-dependent nephritis, we induced nephrotoxic serum nephritis (NSN) in IL-15-/and wild-type (IL-15 +/+) C57BL/6 mice. Contrary to our expectations, IL-15 protects the kidney during this T cell-dependent immunologic insult. Tubular, interstitial, and glomerular pathology and renal function are worse in IL-15-/mice during NSN. We detected a substantial increase in tubular apoptosis in IL-15-/kidneys. Moreover, macrophages and CD4 T cells are more abundant in the interstitia and glomeruli in IL-15-/mice. This led us to identify several mechanisms responsible for heightened renal injury in the absence of IL-15. We now report that IL-15 and the IL-15 receptor (α, β, γ chains) are constitutively expressed in normal tubular epithelial cells (TECs). IL-15 is an autocrine survival factor for TECs. TEC apoptosis induced with anti-Fas or actinomycin D is substantially greater in IL-15-/than in wild-type TECs. Moreover, IL-15 decreases the induction of a nephritogenic chemokine, MCP-1, that attracts leukocytes into the kidney during NSN. Taken together, we suggest that IL-15 is a therapeutic for tubulointerstitial and glomerular kidney diseases.

IL-15, a T cell growth factor, has been linked to exacerbating autoimmune diseases and allograft rejection. To test the hypothesis that IL-15–deficient (IL-15–/–) mice would be protected from T cell–dependent nephritis, we induced nephrotoxic serum nephritis (NSN) in IL-15–/– and wild-type (IL-15+/+) C57BL/6 mice. Contrary to our expectations, IL-15 protects the kidney during this T cell–dependent immunologic insult. Tubular, interstitial, and glomerular pathology and renal function are worse in IL-15–/– mice during NSN. We detected a substantial increase in tubular apoptosis in IL-15–/– kidneys. Moreover, macrophages and CD4 T cells are more abundant in the interstitia and glomeruli in IL-15–/– mice. This led us to identify several mechanisms responsible for heightened renal injury in the absence of IL-15. We now report that IL-15 and the IL-15 receptor (α, β, γ chains) are constitutively expressed in normal tubular epithelial cells (TECs). IL-15 is an autocrine survival factor for TECs. TEC apoptosis induced with anti-Fas or actinomycin D is substantially greater in IL-15–/– than in wild-type TECs. Moreover, IL-15 decreases the induction of a nephritogenic chemokine, MCP-1, that attracts leukocytes into the kidney during NSN. Taken together, we suggest that IL-15 is a therapeutic for tubulointerstitial and glomerular kidney diseases