C4B and Sepsis: As depicted in Figures 2c and 2d, neutrophils incubated with agonistic CH-11 antibodies and sera from sepsis patients immunoprecipitated with ZB4 (low sFas levels) displayed a twofold increased apoptosis rate when compared with cells cultured in the presence of CH-11 antibodies and pooled serum samples (control; high sFas levels).