Complement alternative pathway (AP) activation on proximal tubular epithelial cells (PTECs). PTECs were incubated with different concentrations of normal human serum (NHS; 5% or 25%) for 3 h. Depositions of properdin (P), factor H (fH), C3 and membrane attack complex (MAC) with 25% NHS (c) were stronger than those with 5% NHS (a), as observed by immunofluorescence (IF). Preincubation with P (5 μg/mL) for 3 h before the addition of both 5% (b) and 25% (d) NHS increased the depositions of P, C3 and MAC compared with those with 5% (a) and 25% (c) intact NHS. Quantitative analysis was performed, and preincubation with P before the addition of both 5% and 25% NHS significantly increased depositions of C3 (e, g) and MAC (f, h) (**p < 0.001) compared with the addition of 5% and 25% intact NHS only. Results are expressed as means ± standard errors of values from five representative lesions. Original magnification: ×100 Arrow: depositions of P, fH, C3 or MAC.
Nagamachi et al. BMC Nephrology 2014 15:82 doi:10.1186/1471-2369-15-82