Table I.
Incubation
|
Promastigote bound C3 (%)
|
||
---|---|---|---|
30 s | 120 s |
L. amazonensis
(n) |
L. donovani
(n) |
PBS | NHS | 100 | 100 |
PBS | NHS-EGTA | 8.3 ± 1.7 (4) | 3.2 ± 0.4 (4) |
PBS | IgM | 2.8 ± 1.2 (6) | 3.0 ± 1.4 (6) |
PBS | IgG | 0.8 ± 0.6 (3) | 0.6 ± 0.6 (4) |
PBS | Ads-NHS | 15.1 ± 2.0 (15) | 11.4 ± 1.1 (24) |
NHS-EDTA | NHS | 100 | 100 |
NHS-EDTA | Ads-NHS | 88.8 ± 4.8 (15) | 71.7 ± 5.3 (26) |
IgM-EDTA | Ads-NHS | 88.6 ± 2.7 (13) | 93.8 ± 3.6 (13) |
IgG-EDTA | Ads-NHS | 17.8 ± 1.4 (13) | 17.4 ± 2.9 (13) |
Promastigote triggering of complement activation was analyzed in a two-step binding assay. Promastigotes were preincubated (37°C, 30 s) in 100 μl of PBS, NHS-EDTA, IgM-EDTA, or IgG-EDTA as indicated, washed twice by centrifugation, and incubated (37°C, 120 s) in the conditions indicated. Samples then were processed as described (Materials and Methods). Results are expressed as the percentage of maximum promastigote-bound C3 in NHS (100%) = SEM; (n), number of experiments performed.