Characteristics and results summary of the anti-erythrocyte antibodies studied
| Antibody . | Isotype . | Antigen . | Relative binding to erythrocytes* . | Anemia† . | Induces erythrocyte phagocytosis . | Inhibits platelet phagocytosis . | Ameliorates ITP . |
|---|---|---|---|---|---|---|---|
| TER119 | Rat IgG2b | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| Deglycosylated TER119 | Rat IgG2b | mGPA | ++++ | ++++‡ | No | No | No |
| TER119 | Mouse IgG1 | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| TER119 | Mouse IgG2a | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| M1/69 | Rat IgG2b | CD24 | ++ | +++§ | Yes | Yes | Yes |
| 34-3C | Mouse IgG2a | Band3 | ++++ | +++ | Yes | Yes | Yes |
| 4B7 | Mouse IgG1 | HEL | ++ | − | No | No | No |
| 5B9 | Mouse IgG1 | HEL | ++ | − | No | No | No |
| MIMA29 | Mouse IgG2a | Duffy | ++++ | +++ | No | No | No |
| CBC512 | Mouse IgG1 | Duffy | +++ | ++++ | No | No | No |
| Anti-OVA | Rabbit polyclonal | OVA | ++ | −|| | No | No | No |
| 6A7 | Mouse IgG1 | hGPA | ++ | −|| | No | N/T | No |
| Antibody . | Isotype . | Antigen . | Relative binding to erythrocytes* . | Anemia† . | Induces erythrocyte phagocytosis . | Inhibits platelet phagocytosis . | Ameliorates ITP . |
|---|---|---|---|---|---|---|---|
| TER119 | Rat IgG2b | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| Deglycosylated TER119 | Rat IgG2b | mGPA | ++++ | ++++‡ | No | No | No |
| TER119 | Mouse IgG1 | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| TER119 | Mouse IgG2a | mGPA | ++++ | ++++ | Yes | Yes | Yes |
| M1/69 | Rat IgG2b | CD24 | ++ | +++§ | Yes | Yes | Yes |
| 34-3C | Mouse IgG2a | Band3 | ++++ | +++ | Yes | Yes | Yes |
| 4B7 | Mouse IgG1 | HEL | ++ | − | No | No | No |
| 5B9 | Mouse IgG1 | HEL | ++ | − | No | No | No |
| MIMA29 | Mouse IgG2a | Duffy | ++++ | +++ | No | No | No |
| CBC512 | Mouse IgG1 | Duffy | +++ | ++++ | No | No | No |
| Anti-OVA | Rabbit polyclonal | OVA | ++ | −|| | No | No | No |
| 6A7 | Mouse IgG1 | hGPA | ++ | −|| | No | N/T | No |
HEL, hen egg lysosome; hGPA, human glycophorin A protein; N/T, not tested; mGPA, mouse glycophorin A–associated protein; OVA, ovalbumin.
Antibody binding to erythrocytes was quantified based on the median fluorescence intensity (MFI) at the saturating and/or the highest concentration tested (–≤50, + ≤100, ++ ≤250, +++ ≤500, ++++ ≥500).
Anemia refers to the ability of the antibody to leading to reductions in erythrocyte concentration in circulation (−, <6.25%; +, >6.25%; ++, >12.5%; +++, >25%; ++++, >50% reduction).
TER119 is able to cause anemia by an FcγR,13 macrophage-mediated16 pathway as well as by a cation-driven FcγR/complement-independent pathway.17 As deglycosylation of TER119 would impair FcγR/complement-dependent events, the anemia observed by the deglycosylated TER119 would be anticipated to occur due to the cation-driven FcγR/C3-independent pathway.
The degree of anemia induced by M1/69 varied across the mice strains tested (+++ for C57Bl/6, ++ for BALB/c, and − for CD-1).
Anti-OVA– and 6A7-induced anemia was recorded daily for 6 and 2 days only, respectively (as opposed to daily reading over 8 days).