G. Pozzato et al., Ethnic difference in the prevalence of monoclonal B-cell proliferation in patients affected by hepatitis C virus chronic liver disease, J HEPATOL, 30(6), 1999, pp. 990-994
Background/Aim: In previous studies we demonstrated that all patients affec
ted by HCV-positive type II mixed cryoglobulinaemia have a monoclonal B-cel
l population in peripheral blood mononuclear cells, and that a large fracti
on of HCV-infected patients develop a monoclonal B-cell expansion, even in
the absence of dosable serum cryoglobulins. However, the prevalence of Type
LI mixed cryoglobulinaemia in HCV-infected individuals seems to be high in
Italy, whereas it is very low in Japan. This study was performed to invest
igate whether there are ethnic differences in the prevalence of asymptomati
c HCV-associated monoclonal B-cell expansions.
Methods: Forty-four Japanese patients affected by HCV-positive chronic live
r disease (two healthy carriers, 31 chronic hepatitis and 11 cirrhosis) wer
e compared with a group of 60 Italian patients (one healthy carrier, 49 chr
onic hepatitis, and 10 cirrhosis) without dosable levels of cryoglobulins.
The monoclonality of peripheral blood mononuclear cells was investigated by
RT/PCR analysis of Immoglobulin gene rearrangements. Liver function tests,
rheumatoid factor, cryocrit level, anti-HCV antibodies, HCV-RNA, and HCV g
enotype were performed according to standard methodology.
Results: A B-cell monoclonal population was found in 26% of Italian patient
s, whereas all Japanese patients were negative. No correlation was found be
tween B-cell monoclonality and severity of liver disease, length or source
of the infection, HCV genotype, sex,clinical and biochemical parameters.
Conclusions: This study indicates that a monoclonal B-cell proliferation in
peripheral blood mononuclear cells is common in HCV infection, but only in
Italy, whereas it is absent in Japan. This explains the very low prevalenc
e of Type II mixed cryoglobulinaemia in HCV-positive Japanese subjects, and
suggests that HCV is able to determine a B-cell expansion only in the pres
ence of, presently undetermined, host factors.