Correlation of serum cytokines with occurrence of nephritis in systemic lupus erythematosus (SLE). Measurement of T helper 1 (Th1) and Th2 cytokines by enzyme-linked immunosorbent assay (a) revealed higher concentrations (P < 0·0001) of serum interleukin (IL)-12p70, interferon (IFN)-γ and IL-4 in SLE patients (grey bars; n = 150) than in controls (empty bars; n = 69). (b) IL-12p70 and IFN-γ were increased in patients with lupus nephritis (LN) (group A; grey bars) compared with those without LN (group B; empty bars; P < 0·0001 in both instances), whose IL-4 levels, on the other hand, were higher. (c) IL-12p70 and IFN-γ levels in group A per LN class. Those in subsets IV (empty bars) and V (shaded bars) displayed the highest content of both cytokines (P < 0·05 in both instances by one-way analysis of variance followed by Newman–Keuls test) followed by subsets III (black bars) and II (grey bars). (d,e) Either the positive or the negative correlation between IL-12p70 with IFN-γ and IL-12p40 respectively. Values are expressed as mean ± standard deviation in each group.

Flow cytometry characterization of peripheral interferon (IFN)-γ⁺/interleukin (IL)-4⁺ cells in systemic lupus erythematosus (SLE) patients with and without lupus nephritis (LN). (a–e) Analysis revealed the expansion of IFN-γ⁺cells in representative patients of subsets IV and V with respect to subset III, whose values were almost similar to those of groups B and C. CD3⁺/CD4⁺ population was gated for the analysis. The IFN-γ : IL-4 ratio is indicated. (f) The relative individual IFNγ : IL-4 ratio of the groups detailed in (a–e). *P < 0·05, **P < 0·0001 by one-way analysis of variance test. Number of patients studied and means ± standard deviation (s.d.) are indicated. As shown in (g), stimulated peripheral cells from subsets IV and V released in vitro high amounts of IL-12p70 and IFN-γ compared with cells obtained from group B. By contrast, secretion of IL-4 was unchanged among patients with LN and apparently increased in group B. Values are indicated as means ± s.d.

Glomerular and urinary interleukin (IL)-12p70 expression in lupus nephritis (LN). The upper panel illustrates glomerular expression in biopsy specimens from subsets III (a), IV (b) and V (c). Glomerular IL-12p70 accumulation parallels LN severity: subset IV (b) displayed the highest number of IL-12p70⁺ mononuclear cells [20·5 ± 8 cells/glomerular cross section (gcs), P < 0·05 in both instances] followed by subset V (c: 12·3 ± 2 cells/gcs) and subset III (a: 3·1 ± 0·5 cells/gcs). In addition, group A patients produced higher amounts of urinary IL-12p70 compared with group B and C (d: P < 0·0001) whereas, as shown in (e), their urinary IL-12p70 increment (grey bars) correlated with the severity of LN as it was found increased in subset IV (366 ± 325 units) with respect to the other subsets (P < 0·05). A correlation between renal disease activity and urinary IL-12p70 production was also detected in subset IV (IVa: 476·7 ± 342 units, IVa–c 114 ± 63 units, IVc: 130 ± 61 units; P < 0·05), whereas patients of subset III showed similar urinary IL-12p70 levels (IIIa: 89·0 units, IIIa–c: 144·9 units, IIIc: 92·2 ± 52·3 units) that were unrelated to disease activity. Number of glomerular IL-12p70⁺ cells showed a trend to the increment in subset IVa followed by subsets IVa–c and IVc in parallel to the urinary production. Values are mean ± standard deviation. *P < 0·05, **P < 0·0001 by one-way analysis of variance; a (active) and a–c (active and chronic) segmental and global LN, c (chronic inactive) LN. Medians are indicated in (d).