Technical Comments

Ebola Virus, Neutrophils, and Antibody Specificity

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Science  30 Oct 1998:
Vol. 282, Issue 5390, pp. 843
DOI: 10.1126/science.282.5390.843a

Figures

  • Figure 1

    Flow cytometry assays. Incubation with primary antibody, black solid lines; control FITC-conjugated antibodies alone, red dotted lines. (A) Binding of sGP and Fab fragment (LS4) to neutrophils. No binding was detected when Fab fragments (LS4, KS14, and K518) (20 μg/mL) were premixed with sGP and incubated with neutrophils (left panel: without sGP, right panel: with sGP). Detection was performed with fluorescein isothiocyanate (FITC)–conjugated goat IgG F(ab′)2fragments to human IgG F(ab′)2 (1:100) (Pierce, Rockford, Illinois) (data of KS14 and K518, not shown). (B) Binding of Fab fragment LS4 and sGP to neutrophils in the presence of rabbit anti-sGP serum. Fab LS4 (20 μg/ml) and rabbit anti-sGP serum (1:250) were mixed in the absence (left panel) or the presence (right panel) of sGP and incubated with neutrophils (1.25 × 105 cells). Binding of Fab LS4 to neutrophils was detected only in the presence of both sGP and rabbit anti-sGP serum. Detection was performed with FITC-conjugated goat IgG F(ab′)2 fragments to human IgG F(ab′)2. (C) Binding of sGP (1:10) and purified rabbit IgG against sGP (5 μg/ml) to neutrophils without (left panel) and with (right panel) sGP. Detection was done by FITC-conjugated goat IgG F(ab′)2 fragments to rabbit IgG F(ab′)2 (1:100) (Jackson, West Grove, Pennsylvania). (D) Binding of sGP and rabbit IgG F(ab′)2 fragments against sGP (5 μg/mL) to neutrophils. No binding of rabbit IgG F(ab′)2 fragments against sGP to neutrophils was observed in the absence (left panel) or presence (right panel) of sGP. Detection was done with the use of FITC-conjugated goat IgG F(ab′)2 fragments to rabbit IgG F(ab′)2. Incubations were performed in a 50-μL volume at 4°C for 60 min with sGP and the primary antibody, followed by a 20 min incubation with the FITC-conjugated antibodies. Dilution of sGP, antibodies, serum, and neutrophils and the washing of cells were done with phosphate-buffered saline (PBS) containing 1% fetal calf serum (FCS) and 0.01% NaN3.

  • Figure 2

    Binding of antibodies and antibody fragments to sGP by ELISA. Wells were coated with sGP (1:10 in PBS) at 4°C overnight. After washing 5× with PBS/0.05% Tween 20, the wells were blocked with 4% (w/v) nonfat dry milk (Bio-Rad, Hercules, California)/PBS. Rabbit IgG and IgG F(ab′)2fragments to sGP were serially diluted and added to the wells. Detection was done with alkaline phosphatase-conjugated goat IgG to rabbit IgG F(ab′)2 (1:500) (Pierce, Rockford, Illinois). Human Fab LS4 was included as a control and detected by alkaline phosphatase-conjugated goat IgG to human IgG F(ab′)2(1:500) (Pierce). Incubations were performed at 37°C for 60 min. Rabbit IgG and IgG F(ab′)2 fragments showed similar binding reactivity to sGP.

  • Figure 3

    Absorption test of sGP with purified neutrophils. sGP (1:10) was incubated with purified neutrophils (1×107) at 4°C for 60 min in a 50-μl volume, after which the cells were removed by centrifugation. Supernatant containing unabsorbed sGP was serially diluted in 1% FCS/PBS/0.01% NaN3 and transferred to ELISA wells coated with rabbit IgG against sGP (4 μg/ml). Plate was washed and incubated with Fab LS4 (4 μg/ml). Bound Fab was detected with alkaline phosphatase-conjugated goat IgG to human IgG F(ab′)2 (1:500) (Pierce, Rockford, Illinois). sGP not incubated with neutrophils was also serially diluted and detected in the same ELISA. ELISA incubations were performed at 37°C for 60 min, and wells were washed 5× with 0.05% Tween 20–PBS at each step. No absorption of sGP by neutrophils was as observed compared with the control wells (no incubation with neutrophils).

  • Figure 1

    Potentiation by IgG of sGP binding to human neutrophils detected by F(ab′)2 reagent. (A) Freshly isolated human neutrophils from healthy donors (2 × 106) were incubated with sGP or control supernatants for 30 min on ice. Cells were spun and washed once with 1 ml of ice-cold PBS. One hundred microliters of diluted antiserum to GP/sGP (1:1000) was added and incubated on ice for 30 min. Cells were spun again and washed with 1 ml of PBS. Finally, 100 μl of 1:75 diluted FITC-conjugated affiniPure (Fab′)2fragment goat anti-rabbit IgG-(Fab′)2 (Jackson, West Grove, Pennsylvania) was added and incubated on ice for 30 min. Cells were washed once with PBS and resuspended in PBS + 1% formaldehyde for fluorescence-activated cell sorter (FACS) analysis. (B) Cells were incubated with sGP and control supernatants as in (A), and followed by an incubation of 1:100 diluted purified IgG (Fab′)2 fragment rabbit antibody to GP/sGP (0.4 mg/ml). Finally, the cells were incubated with FITC (Fab′)2 fragment goat antibody to rabbit IgG(Fab′)2 for 30 min on ice. Cells were washed once with 1 ml of ice-cold PBS after each step and resuspended in PBS + 1% formaldehyde for FACS analysis. (C) Cells were pre-incubated with 1 μg of rabbit IgG (Sigma, St. Louis, Missouri) in 100 μl on ice for 30 min, followed by the incubations described in (B). Cells were washed once with 1 ml of ice-cold PBS after each step.

  • Figure 2

    Correct image, showing a FACS profile from lymphocytes, that should have appeared in our report (1, p. 1034) as the far-left graph in figure 1A.

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