Th1 (IL-2, interferon-gamma (IFN-gamma)) and Th2 (IL-10, IL-4) cytokine production by peripheral blood mononuclear cells (PBMC) from patients with systemic lupus erythematosus (SLE)

Abstract

We investigated the production of IL-2, IFN-gamma, IL-10 and IL-4 by PBMC from 24 patients with SLE and 10 healthy individuals. Basal and mitogen-stimulated (lipopolysaccharide and phytohaemagglutinin (LPS + PHA)) cytokine production was determined in a whole blood assay (WBA). Supernatants were collected and assayed with specific ELISAs. Although the IL-2 and IFN-gamma contents did not differ significantly between patients and controls under both conditions, statistically significant correlations were found between each cytokine and disease activity (SLAM index) after stimulation (respectively, r = 0.501, P = 0.01 and r = 0.631, P = 0.001). PBMC IL-10 production was significantly higher for patients than controls (P = 0.05), but no correlation between IL-10 levels and the SLAM index was obtained. IL-4 production was not statistically different between SLE patients and controls. For stimulated WBAs, the IL-10/IL-2 and IL-10/IFN-gamma ratios were significantly correlated with disease severity (P = 0.02; P = 0.001, respectively). Overall, our data suggest that SLE is characterized by an elevated production of IL-10, reflecting the basal state of activation of the immune system. During exacerbation of SLE, IL-2 and IFN-gamma are synthesized in larger amounts and may cause the tissue damage observed.

Fig. 1

Correlations between IL-2 (a) and IFN-γ (b) cytokine production after 24 h of whole blood culture in patients with SLE and systemic lupus activity measure (SLAM) values. Basal, unstimulated culture conditions; LPS + PHA, mitogen-stimulated culture conditions. Results are expressed in pg/10⁶ PBMC as estimated on the haemogram for IL-2 and in U/10⁶ PBMC for IFN-γ. Correlations were determined by linear regression and Spearman's rank correlation.

Fig. 2

Correlations between IL-10 (a) and IL-4 (b) cytokine production after 24 h (IL-4) or 48 h (IL-10) of whole blood culture in patients with SLE and systemic lupus activity measure (SLAM) values. Basal, unstimulated culture conditions; LPS + PHA, mitogen-stimulated culture conditions. Results are expressed in pg/10⁶ PBMC as estimated on the haemogram. Correlations were determined by linear regression and Spearman's rank correlation.