Has no protease activity. May reduce cytokine release in response to bacterial lipopolysaccharide during infections. Reduces activation of NF-kappa-B in response to TNF. Detected in heart, kidney, liver, lung, pancreas, small intestine, spleen, stomach, thymus and testis. The most frequent variant has a stop codon instead of Arg-125, giving rise to truncated forms of isoform 1 (named delta, epsilon, eta, gamma) and isoform 3 (iota, teta). The variant Arg-125 (Csp12-L) is rare, except in some populations from sub-Saharan Africa. Csp12-L may increase the susceptibility to severe sepsis, and may also increase the mortality rate in sepsis patients. Belongs to the peptidase C14A family.