Figure 4.

Complement activation by switch variant monoclonal antibodies. A. Immunofluorescence staining of glomeruli for C1q, C4 and C3 after 15mg/kg anti-TNP monoclonals with endotoxin, or endotoxin alone (control), given 24 hours after an intravenous injection of TNP conjugated nephrotoxic antibody. In the control group there was no C1q present, with sparse mesangial C3 and prominent mesangial C4. After IgG2a or IgG2b linear capillary wall C1q, C3 and C4 staining was present. In the case of C3 and C4, this was superimposed on the mesangial staining, with more C3 and C4 after IgG2b. There was no C1q, C3 or C4 deposited after injection of IgG1 anti-TNP. B. Quantitative data confirming the above findings.