Serum Neopterin Level in Systemic Lupus Erythematosus: Could it be used as an Immunemarker of Disease Activity and its Comparison with other Disease Activity Parameters

Systemic lupus erythematosus (SLE) has always been associated with numerous abnormalities in the immune system including activation of both the humoral as well as the cellular immunity. Distinguishing patients with active SLE from those with inactive disease has always been considered a great challenge. Identifying laboratory parameters that distinguish patients with active disease from those with inactive form has been reported to be a major challenge in the clinical management of SLE. Humoral immune system activation can be reflected on ESR, plasma complement concentrations and formation of anti-ds DNA. These tests are currently used as indicators for disease activity. Meanwhile, other tests can be used indicating primary cellular immune system activation reflecting T lymphocyte upregulation. Particular attention has been focused on neopterin level, which has been shown to be an early, specific and sensitive marker of cellular immune system activation in several clinical settings including autoimmune and inflammatory diseases. Thus, special attention has recently been focused on neopterin as an important indicator for assessing SLE activity. To investigate serum neopterin level as a parameter of disease activity in an unselected group of SLE patients and its comparison and correlation with the other parameters currently used, the present study has been performed. This study also investigates the relation between serum neopterin and certain patterns of organ disease involvement as well as its relation with the different types of treatment regimens used in the management of SLE. The study included 100 subjects divided into two main groups: group 1 included 50 SLE patients who were further subdivided into subgroup 1 A (21 active SLE patients) and subgroup I B (19 inactive SLE patients) and group II included 50 apparently healthy age and sex-matched subjects taken as a control group. All subjects included in this study were properly evaluated by thorough history taking including history of various organs affection and the medications used as well as by full physical examination. Various biochemical blood tests were performed in addition to ESR estimation by the Seditainer ESR system, detection of antinuclear and antidouble strand DNA antibodies (ANA and anti-ds DNA) using indirect immunofluorescence, plasma C3, C4, as well as C3dg by a double decker immunodiffusion method. Serum neopterin level determination was done by using commertially available enzyme linked immunosorbent assay kit. Our data demonstrated a highly significant increase in serum neopterin level in SLE patients compared to normal controls, in the active SLE patients compared to the inactive ones and in the inactive SLE patients compared to the normal controls as well. Thus, our study demonstrated a highly significant association between serum neopterin level and disease activity in patients with SLE. Our study clearly demonstrated a highly significant positive correlation detected between serum neopterin level and each of plasma C3dg level, anti-ds DNA and ESR. Meanwhile, a highly significant negative correlation was also detected in our study between serum neopterin level and both plasma C3 and C4 levels. The study also shows that serum neopterin level can be used as a specific as well as a sensitive marker for detecting SLE activity. As regarding various treatment regimens used in the management of active SLE, our study demonstrated less disease activity in patients receiving combined treatment of both prednisolone and cytotoxic drugs than those receiving either treatment alone and activity is less in those receiving cytotoxic drugs only than those receiving prednisolone only as a treatment as being reflected on various parameters used to assess disease activity. Our study demonstrated no significant difference detected in serum neopterin level in patients with different patterns of various organ system diseases in SLE, while a significant difference was detected comparing patients with multiple organ affection to those with single organ affection regardless of the type of the organ affected, indicating increased disease activity in multiorgan affection disease. We concluded that serum neopterin level could be used in SLE patients as an indicator for disease activity. It can be used as a marker for assessing and monitoring not only disease activity but also efficacy of the various treatment regimens used. Our study also concluded that SLE is more active in patients with multi organ system affection than those with single organ affection regardless of the type of organ involvement. We also concluded that patients receiving a combined therapy of both prednisolone as well as cytotoxic drugs have less active disease compared to those receiving either prednisolone alone or cytotoxic drugs alone.