Abnormal clearance from the mononuclear phagocytic system of immune complexes (IC)

Abnormal clearance from the mononuclear phagocytic system of immune complexes (IC) is important in the pathogenesis of systemic lupus erythematosus (SLE). in the human IC transfer reaction that includes an adhesive function which facilitates IC processing by mononuclear phagocytes. Finally, a functional effect of the FcRIIa R131/H131 polymorphism, important in susceptibility to SLE, has also been demonstrated using this model. Uptake of IgG2 but not IgG1-containing soluble IC was reduced by macrophages from individuals homozygous for the R131 allelic variant of the receptor. studies have demonstrated that the clearance of soluble IC is abnormal in patients with SLE. For example, when compared to normal subjects the mean half-time for initial clearance of radiolabelled heat-aggregated gamma globulin (HAGG) was shorter in patients with SLE [7]. Experiments performed in our own laboratory using radiolabelled hepatitis B surface antigen (HBsAg)/anti-HBsAg IC demonstrated accelerated uptake of this probe by the liver, but subsequently defective retention of the IC within the organ, with return of the complexes to the circulation [8]. Uptake and retention of the IC by the spleen were also reduced. The hypothesis for this defective retention of IC was that only those complexes able to interact with both Fc and complement receptors are retained effectively within the organ. This hypothesis was tested later using smaller HBsAg/anti-HBsAg IC that activated complement poorly than that by cells from R131 homozygotes [13], this raises the possibility that impaired clearance of IC containing anti-C1q antibodies in particular may be important TWS119 in the pathogenesis of lupus nephritis. The precise cellular mechanisms involved in the transfer of soluble IC from erythrocytes to macrophages remain to TWS119 be delineated fully. In contrast to studies performed models have been developed to explore these mechanisms in detail. Emlen model to investigate the contribution of individual phagocytic receptors involved in the transfer of soluble IC from erythrocytes to human monocytes and monocyte-derived macrophages. In this model monolayers of these cells had been subjected to IC shipped bound Rabbit Polyclonal to MRPS27. to human being erythrocytes which were perfused through a parallel-plate movement chamber system, created in our lab for the analysis of leucocyteCendothelial cell relationships [16,17]. We’re able to demonstrate transfer of IC from erythrocytes to mononuclear cells using confocal microscopy. In recirculation tests a progressive lack of IC from erythrocytes during perfusion over macrophage monolayers was noticed, correlating with uptake from the macrophage monolayer. We’ve defined the go with and Fc receptors necessary for IC transfer under movement and those mixed up in adhesive discussion between erythrocytes and macrophage monolayers. The info suggest differing jobs for these receptors in the transfer response, including an adhesive function that facilitates IC digesting by mononuclear phagocytes. Finally, we demonstrate a defect in the uptake TWS119 of IgG2 IC under movement by macrophages from people homozyogous for the R131 variant of FcRIIa. Strategies and Components Antibodies Mouse anti-human MoAb 10.1 (isotype IgG1 kappa) against FcRI (CD64) was from Dako (Glostrup, Denmark). This antibody reacts with an epitope close to the binding site for the Fc region of human IgG, blocking the binding of human TWS119 IgG to this receptor [18]. Mouse anti-human MoAb 3G8 (IgG1) against FcRIII (CD16) was obtained from Immunotech (Marseille, France). This MoAb reacts with both FcRIIIa and FcRIIIb and blocks IC binding to the receptor. TWS119 The mouse anti-human antibody IV.3 (IgG2b) against FcRII (CD32) was purified from mouse hybridoma supernatant (ATCC, Manassas, VA, USA). This MoAb binds preferentially to FcRIIa rather than FcRIIb [19], and blocks the binding of IgG to FcRIIa [20]. The mouse anti-human CR1 MoAb To5 (IgG1) was obtained from Dako. This antibody inhibits the binding of C3b to erythrocytes, neutrophils, B lymphocytes, monocytes and macrophages [21]. Mouse anti-human CR1 MoAb 3D9 was a gift from Professor J. Atkinson (University of.