Journal: Journal of immunology (Baltimore, Md. : 1950)

Article Title: Epidermal growth factor receptor targeting IgG3 triggers complement-mediated lysis of decay-accelerating factor expressing tumor cells through the alternative pathway amplification loop.

doi: 10.4049/jimmunol.1400329

Figure Lengend Snippet: FIGURE 4. CML triggered by anti–EGFR-IgG3 negatively correlates with CD55 and CD59 expression levels. (A) Surface expression levels of CD46, CD55, and CD59 on analyzed cell lines were quantified by calibrated flow cytometry. Means 6 SEM of at least three independent experiments are presented. (B) Correlations between CD46, CD55, or CD59 and anti–EGFR-IgG3–mediated CDC were calculated for all four cell lines. CDC results at 2 mg/ml Ab concentration were taken from experiments presented in Fig. 2. (C) A431 cells were seeded into 10-cm plates and grown overnight. On the following day, cells were transfected with 50 nM control siRNA or with single siRNAs specific for CD46, CD55, CD59, or with a combination of all three mCRP-specific siRNAs for 72 h. Efficiency of siRNA-induced knockdown was analyzed by direct flow cytometry using fluorochrome-labeled, mCRP- specific Abs (CD46-Pacific blue, CD55-PE, CD59-FITC), or respective control Abs. (D–G) CDC against control siRNA or mCRP-specific, siRNA- transfected A431 cells was analyzed by 3-h [51Cr] release assays in the presence of 25% v/v human serum and anti–EGFR-IgG1 (upper panels), anti– EGFR-IgG3 (lower panels), as well as the respective control Abs at increasing concentrations. (H) Concentration-dependent binding of CD55-Ab (BRIC216, mouse IgG1) to A431 cells was analyzed by indirect immunofluorescence. Results from one representative experiment are presented. (I) CDC triggered by anti–EGFR-IgG1, anti–EGFR-IgG3, or respective control Abs (all at 66.67 nM) against A431 cells in the presence of saturating concentrations of CD55-Ab or a control Ab (both at 66.67 nM) was analyzed by 3-h [51Cr] release assays in the presence of 25% v/v human (Figure legend continues)

Article Snippet: To block complement regulatory activity of CD55, we used mouse anti-human CD55 (66.67 nM, BRIC216, mouse IgG1; Bio-Rad) blocking mAb in CDC experiments at saturating concentrations.

Techniques: Expressing, Cytometry, Concentration Assay, Transfection, Control, Knockdown, Labeling, Binding Assay

Journal: Journal of immunology (Baltimore, Md. : 1950)

Article Title: Epidermal growth factor receptor targeting IgG3 triggers complement-mediated lysis of decay-accelerating factor expressing tumor cells through the alternative pathway amplification loop.

doi: 10.4049/jimmunol.1400329

Figure Lengend Snippet: FIGURE 5. CD55 dampens anti–EGFR-IgG3–triggered CML and promotes C1q-dependent induction of AP amplification. BHK-EGFR+ #5 cells were transiently transfected with a control vector or a CD55 vector for 48 h. (A) Cell-surface expression of CD55 was analyzed by direct flow cytometry using PE-conjugated CD55-specific or control Abs. (B–D) The influence of CD55 overexpression on anti–EGFR-IgG3–mediated CDC was investigated by [51Cr] release assays either (B) in an Ab concentration–response curve, (C) in a time-dependent manner, or (D) in serum titration experiments. (E–H) The influence of the alternative complement pathway inhibitor CRIg (E and G), the presence of C1q in serum (F; at 66.67 nM Ab concentration; mean 6 SEM of triplicates), as well as of factor B (H; 13.33 nM Ab concentration, 12.5% v/v factor B–depleted serum, 200 mg/ml factor B), on anti–EGFR-IgG3–mediated CDC was analyzed using either (E and F) control vector–transfected or CD55 vector–transfected BHK-EGFR+ #5 cells or (G and H) DiFi cells (66.67 nM Ab concentration). (I) Deposition of factor Bb on control vector– or CD55 vector–transfected BHK-EGFR+ #5 cells was analyzed by flow cytometry. Relative deposition levels were calculated by equating RFI measured in the absence of Ab with 100%. Results are presented as mean 6 SEM of at least three independent experiments with different blood donors. *p # 0.05 anti–EGFR-IgG3 versus respective control Ab; (B–D, I) #p # 0.05 control vector versus CD55 vector; (E and G) #p # 0.05 without CRIg-Fc versus CRIg-Fc; (H) #p # 0.05 w/o factor B versus with factor B.

Article Snippet: To block complement regulatory activity of CD55, we used mouse anti-human CD55 (66.67 nM, BRIC216, mouse IgG1; Bio-Rad) blocking mAb in CDC experiments at saturating concentrations.

Techniques: Transfection, Control, Plasmid Preparation, Expressing, Cytometry, Over Expression, Concentration Assay, Titration

Journal: Journal of immunology (Baltimore, Md. : 1950)

Article Title: Epidermal growth factor receptor targeting IgG3 triggers complement-mediated lysis of decay-accelerating factor expressing tumor cells through the alternative pathway amplification loop.

doi: 10.4049/jimmunol.1400329

Figure Lengend Snippet: FIGURE 6. Overview of complement activation by human anti–EGFR-IgG3 in the context of CD55 expression. On CD55-deficient target cells (left panel), anti–EGFR-IgG3 mediates strong C3b but low C4b deposition and induces assembly of classical and alternative C3 convertases, predominantly resulting in the induction of fast and efficient CDC via the classical pathway of complement activation. In contrast, on CD55-expressing target cells (right panel), CD55 mainly accelerates the decay of low amounts of classical C3 convertases, leading to amplification of the AP and finally to slow and inefficient CDC induction.

Article Snippet: To block complement regulatory activity of CD55, we used mouse anti-human CD55 (66.67 nM, BRIC216, mouse IgG1; Bio-Rad) blocking mAb in CDC experiments at saturating concentrations.

Techniques: Activation Assay, Expressing