The kinetics of the
immunoglobulin (Ig) M type antibody to the hepatitis D virus (
IgM anti-HD) were investigated in
hepatitis B surface antigen (
HBsAg) carriers with
chronic hepatitis D treated with
interferon (IFN) and in patients with terminal hepatitis delta virus (HDV)
cirrhosis who underwent
liver transplantation. The
IgM antibody disappeared in each of 8 patients who responded to IFN
therapy with the persistent normalization of
aminotransferases and with the clearance of serum
HBsAg and HDV-
RNA. The
IgM reactivity did not decline in the 45 treated patients who did not respond to the
cytokine or who experienced a relapse after responding while on
therapy. The antibody rapidly disappeared from serum post-
transplantation in each of 10 examined patients with HDV who underwent
transplantation. In 5 patients who underwent
transplantation and who became reinfected with HDV, the antibody remained undetectable during the early
reinfection phase, as marked by HDV replication and by the absence of liver damage; however, it rapidly raised to pre-
transplantation levels with the recurrence of
hepatitis D (HD) in the liver graft. Monomeric 7S
IgM anti-HD predominated over pentameric 19S antibody in each of the two patients examined for
IgM anti-HD molecular species. The
IgM antibody to HDV raises in response to HDV-induced damage and represents a valid
surrogate marker of liver damage which is immunopathologically related to HDV
infection. Besides providing diagnostic information, it provides the best predictor of impending resolution of chronic HDV disease, whether spontaneous or IFN-induced.