Ahlin Erik, Elshafei Amir, Nur Musa, El Safi Sayda Hassan, Johan Ronnelid, Elghazali Gehad
Unidade de Imunologia Clínica, Uppsala University, Suécia.
Rev Bras Reumatol. 2011 Dec;51(6):579-86.
The present study evaluated the presence of anti-cyclic citrullinated peptides antibodies (anti-CCP), rheumatoid factor (RF), and circulating immune complexes (CIC) in Sudanese patients infected with the Leishmania donovani parasite.
Sera were collected from Leishmania infected patients (n = 116) and healthy Sudanese (n = 93). Nineteen Sudanese anti-CCP+ RA patients were included as positive controls. Levels of CIC and anti-CCP were measured by ELISA. Control plate with cyclic control peptides containing arginine instead of citrulline was used to evaluate citrulline specifi c reactivity.
Among Leishmania-infected patients and anti-CCP+ RA patients, most were RF positive (86%), while the frequency of CIC positivity was higher among visceral leishmaniasis (VL) patients (VL 38%; anti-CCP+ RA 24%). When anti-CCP reactivity was analysed, 12% of VL patients were found to be positive. The levels of anti-CCP among VL patients correlated well with the CIC levels found (r = 0.65, P < 0.0001). In RA group, no association was found between CIC and anti-CCP. The possibility that anti-CCP positivity was due to cross reactions with CIC was experimentally ruled out. Contrary to what was seen in Sudanese RA sera, the CCP reactivity was not restricted to citrulline but reacted equally well with the arginine control peptide.
The finding that CCP reactivity was not restricted to citrulline argues that this is more an effect of extensive inflammation and immune activation than a sign of shared pathogenic characteristics with anti-CCP arthritis. Our fi ndings stress the importance to interpret a positive CCP test carefully when evaluated in non-rheumatic conditions or in areas where such infections predominate.
本研究评估感染杜氏利什曼原虫的苏丹患者体内抗环瓜氨酸肽抗体（抗CCP）、类风湿因子（RF）和循环免疫复合物（CIC）的存在情况。
收集利什曼原虫感染患者（n = 116）和健康苏丹人（n = 93）的血清。纳入19例苏丹抗CCP阳性类风湿关节炎患者作为阳性对照。采用酶联免疫吸附测定法（ELISA）检测CIC和抗CCP水平。使用含精氨酸而非瓜氨酸的环状对照肽的对照板评估瓜氨酸特异性反应性。
在利什曼原虫感染患者和抗CCP阳性类风湿关节炎患者中，大多数为RF阳性（86%），而内脏利什曼病（VL）患者中CIC阳性频率更高（VL为38%；抗CCP阳性类风湿关节炎患者为24%）。分析抗CCP反应性时，发现12%的VL患者呈阳性。VL患者中抗CCP水平与所检测到的CIC水平密切相关（r = 0.65，P < 0.0001）。在类风湿关节炎组中，未发现CIC与抗CCP之间存在关联。通过实验排除了抗CCP阳性是由于与CIC交叉反应所致的可能性。与苏丹类风湿关节炎血清中所见情况相反，CCP反应性不限于瓜氨酸，与精氨酸对照肽反应同样良好。
CCP反应性不限于瓜氨酸这一发现表明，这更多是广泛炎症和免疫激活的结果，而非与抗CCP关节炎具有共同致病特征的标志。我们的研究结果强调，在非风湿性疾病或此类感染占主导的地区进行评估时，仔细解读CCP检测阳性结果的重要性。
