C-reactive protein, C3, C4 and properdin during the Jarisch-Herxheimer reaction in early syphilis.

The occurrence of plasma CRP during the febrile response after the first injection of penicillin was followed in 10 patients with early syphilis. An increase in CRP was noted after 12 hours, with a maximum after 24 hours. The appearance of this acute phase protein could not be correlated to cutaneous reaction, increased body temperature or leukocytosis, nor were baseline values of CRP correlated to clinical or serological activity of the infection. Patients with high levels of CRP prior to treatment suffered the most intense systemic reactions. No activation of the complement system during the Jarisch-Herxheimer reaction was detected from sequential determinations of C3, C4 and properdin.