Systemic lupus erythematosus (SLE) is a complex autoimmune disease that may result
from defective functions of the immunoregulatory T cell circuits. Cytokines play an
essential role in molding the quality of an immune response to foreign or self-antigens.
With the growing literature regarding cytokine production in autoimmune diseases, an
important role for an active Th 1 response, characterized by production of IFN-y, IL-2, fL-
12 and TNF-a has become evident. On the contrary, there have also been repeated
observations of high levels of type 2 cytokines (IL-4, IL-5, IL-l 0, IL-6 and IL-13)
particularly in the systemic autoimmune diseases.
Objectives: To determine the circulating serum levels of two Th I (IL-2, IFN-y) and
two Th2 (IL-6, IL-13) cytokines in patients with systemic lupus erythematosus (SLE), to
compare serum level of IL-2, IFN- y, IL-6 and IL-13 with the disease activity in SLE
patients and to assess the relationship between serum level of cytokines (IL-2, IL-6, lL-
13 and IFN-y) and different organ involvement in SLE patients.
Methodology: We included 90 SLE patients and 30 healthy controls in this
comparative cross sectional study carried out in Hospital Universiti Sains Malaysia
(USM) and General Hospital Kota Bharu from October 2003 until September 2005 by
selecting SLE patients in medical wards and outpatient clinics. Serum levels of cytokines
were measured by ELISA (IL-2, interferon (IFN) y, IL-6 and IL-13) as well as antidsDNA,
ANA, C3 and C4 complement levels were determined. Disease activity was
recorded according to the Systemic Lupus Erythematosus Disease Activity Index(SLEDAI) and classified as high activity (SLEDAI > 8) or low activity (SLEDAI :S 8).
Different organ affected at any time during the course of the disease was recorded.
Results: The mean age of the patients was 31 .0± 10.8 years. Out of 90 SLE patients, 81
were females (90%) and 9 males (10%). Majority was Malay (92.2%) and the rest was
Chinese (7.8%). 52 patients (57.8%) were inactive SLE (SLEDAI score 0-8) and 38
patients (42.2%) active SLE (SLEDAI score >8). Serum levels of cytokines in SLE
patients were significantly higher than in healthy control with the exception of IL-2 (IFN'
Y p<O.OO 1, IL-6 p<O.OO 1, IL-13 p=0.002, IL-2 p= 0.639). There were also significant
differences between active and inactive SLE patients with the exception of IL-2 (IL-6 p
<0.001 , IL-1 3 p = 0.009, IFN-y p <0.001and IL-2 p =0.087). There was a positive
correlation between Th I (IFN- y) and Th2 (IL-6 and IL-1 3) cytokines with the disease
activity ((IFN-y p=0.002, IL-6 p<O.OO 1, IL-1 3 p=0.006, IL-2 p= 0.151 ). There was
significant correlation between serum level of IL-1 3 and musculoskeletal involvement (p
=0.0 16) and also IL-6 with haematological involvement (p =0.003).
Conclusion: The serum levels of Th2 (IL-6 and IL-1 3) and Th I (IFN- y) cytokines
were significantly elevated and correlated with disease activity in SLE patients. Serum
cytokine level could provide useful information about disease activity in SLE patients