FRI0090 The presence of microchimerism in systemic lupus erythematosus: preliminary data

Background The development of microchimerism after solid organ transplantation, but also after blood transfusions and during pregnancy, is no longer considered controversial. Controversy still exists on the immunological significance of this phenomenon, such for example its role on the development of tolerance to the graft, or of some autoimmune conditions such as scleroderma (SSc). In this respect several studies have showed the presence of fetal cells not only in the peripheral blood but also in the skin of SSc patients. These observations, along with epidemiological (female prevalence, onset after childbearing years) and clinical (similarities with chronic graft versus host disease) data, have led to the hypothesis that microchimerism may play a role in the aetiopathogenesis of this disease. Objectives The aim of our study was to evaluate the prevalence of microchimerism in a population of SLE patients in comparison with SSc patients followed at our Unit. Methods Anticoagulated peripheral blood was obtained from 22 female patients (13 SLE and 9 SSc) who had a previous male pregnancy followed at our Unit. Genomic DNA was isolated from anticoagulated blood using a DNA extraction kit. A specific Y-chromosome sequence was detected by amplifying DNA in a nested-polymerase chain reaction (PCR) using published primers. Results Microchimerism was present in 62% of SLE patients and 89% of patients with SSc, the mean time interval between the pregnancy and the analysis was of 27 years and no significative differences were observed between positive and negative patients. In all scleroderma patients the pregnancy occurred before the onset of the disease (onset of Raynaud’s phenomenon). In SLE patients 38% of the pregnancies occurred before the onset of the disease, and 62% after the onset of the disease, however no differences in the development of microchimerism were observed. Conclusion Since the literature data report a prevalence of 33% of microchimerism in healthy controls, these preliminary data may suggest that microchimerism develops more easily in patients with various autoimmune conditions. Further studies on extended populations of CTD patients and healthy controls appear necessary, in order to look for permissive factors for its development, such for example immunosuppressive therapy or immunological abnormalities. References Evans PC, et al. Blood 1999;93:2033–7 Nelson JL. Lupus 1999;8:370–4 Nelson JL. Curr Opin Rheumatol. 1998;10:564–71