Mathsson Linda, Lampa Jon, Mullazehi Mohammed, Rönnelid Johan
Unit of Clinical Immunology, Uppsala University, Uppsala, Sweden.
Arthritis Res Ther. 2006;8(3):R64. doi: 10.1186/ar1926. Epub 2006 Mar 28.
Immune complexes (ICs) can induce production of cytokines by peripheral blood mononuclear cells via Fc receptors. Rheumatoid factor (RF) develop in response to ICs in many clinical and experimental settings. We investigated whether and how polyethylene glycol (PEG) precipitated ICs from rheumatoid arthritis (RA) sera and synovial fluid (SF) can influence cytokine production by peripheral blood mononuclear cells. We also examined the relationship between RF and IC induced cytokine production. Parallel sera and SF from 47 RA patients and sera from 15 healthy control individuals were PEG precipitated. The precipitates were added to serum-free peripheral blood mononuclear cell cultures and tumour necrosis factor (TNF)-alpha levels were measured after 20 hours. In separate cell culture experiments FcgammaRIIa and FcgammaRIII were blocked and monocytes were depleted or enriched. RF in serum was determined by nephelometry, and IgG levels in precipitates and anti-cyclic citrullinated peptide antibodies in serum were measured using ELISA. Clinical data were collected from the patients' charts. In two separate investigations, we demonstrated a correlation between RF, PEG-precipitated IgG levels and induction of the proinflammatory cytokine TNF-alpha by PEG-precipitated SF ICs. No such correlation was found for serum ICs. TNF-alpha levels induced by SF precipitates, but not serum precipitates, correlated with the number of swollen and tender joints. Monocytes/macrophages were shown to be the main responder cells, and blockade of FcgammaRIIa, but not blockade of FcgammaRIII, inhibited TNF-alpha production in cultures stimulated with precipitated ICs. Anti-cyclic citrullinated peptide correlated with RF but exhibited no association with IgG content in PEG precipitates or with precipitate-induced TNF-alpha levels. These findings support the hypothesis that SF ICs and correlated RF production are directly linked to cytokine-dependent inflammation in RA. Suppression of monocytes/macrophages in RA joints or blockade of the primate-specific activating FcgammaRIIa receptor might be ways to reduce IC-induced TNF-alpha production in the joints of seropositive RA patients.
免疫复合物（ICs）可通过Fc受体诱导外周血单个核细胞产生细胞因子。在许多临床和实验环境中，类风湿因子（RF）会针对ICs产生。我们研究了聚乙二醇（PEG）从类风湿关节炎（RA）血清和滑液（SF）中沉淀出的ICs是否以及如何影响外周血单个核细胞的细胞因子产生。我们还研究了RF与IC诱导的细胞因子产生之间的关系。对47例RA患者的平行血清和SF以及15名健康对照个体的血清进行PEG沉淀。将沉淀物加入无血清的外周血单个核细胞培养物中，并在20小时后测量肿瘤坏死因子（TNF）-α水平。在单独的细胞培养实验中，阻断FcγRIIa和FcγRIII，并去除或富集单核细胞。通过散射比浊法测定血清中的RF，并使用酶联免疫吸附测定法测量沉淀物中的IgG水平和血清中的抗环瓜氨酸肽抗体。从患者病历中收集临床数据。在两项独立研究中，我们证明了RF、PEG沉淀的IgG水平与PEG沉淀的SF ICs诱导促炎细胞因子TNF-α之间存在相关性。血清ICs未发现此类相关性。SF沉淀物而非血清沉淀物诱导的TNF-α水平与肿胀和压痛关节的数量相关。单核细胞/巨噬细胞被证明是主要的反应细胞，阻断FcγRIIa而非阻断FcγRIII可抑制沉淀的ICs刺激培养物中TNF-α的产生。抗环瓜氨酸肽与RF相关，但与PEG沉淀物中的IgG含量或沉淀物诱导的TNF-α水平无关。这些发现支持了以下假设，即SF ICs和相关的RF产生与RA中细胞因子依赖性炎症直接相关。抑制RA关节中的单核细胞/巨噬细胞或阻断灵长类特异性激活的FcγRIIa受体可能是减少血清阳性RA患者关节中IC诱导的TNF-α产生的方法。
