Background/Aims: The outcome of acute hepatitis B infection may be inf
luenced by host factors like the major histocompatibility complex (MHC
), We have investigated MHC class I and class II antigens in patients
with chronic hepatitis B compared to a healthy control population, To
confirm the findings of this first study we performed a second study i
n a group of subjects who had spontaneously recovered from acute hepat
itis B infection. Methods: Frequencies of MHC class I and class II ant
igens were analyzed in patients with chronic hepatitis B virus infecti
on and in control subjects, MHC class I typing was done by standard mi
cro-lymphocytotoxicity assays, DRB1 and DQA1 genotypes were determined
by polymerase chain reaction based typing methods. Results: In the fi
rst study the class II allele HLA-DRB11301-02 was found in 4 of 70 su
bjects with chronic hepatitis B virus infection (5.7%) compared to 27
of 101 healthy controls (26.7%, relative risk 0.17; p = 0.001; p(corr)
= 0.025), This protective effect of the DRB11301-02 allele was confi
rmed in the second study, Eight of 24 patients (33.3%) who cleared hep
atitis B virus spontaneously were positive for DPB11301-O2 (relative
risk of developing chronic infection compared to chronic hepatitis B s
ubjects 0.12; p = 0.004), Subtyping confirmed that 1301 and 1302 were
both decreased in frequency in patients with chronic hepatitis B. Conc
lusions: The MHC class II allele DRB1 1301-02 is associated with prot
ection from chronic hepatitis B in Caucasian patients.