Relationship between autoimmune hepatitis and HLA-DR4 and DRβ allelic sequences in the third hypervariable region in Chinese

AIM: To analyze the association of HLA-DRB1 with autoimmune hepatitis (AIH) in patients from China.

METHODS: In 32 patients and 48 healthy controls, polymerase chain reaction amplification with sequence-specific primers (PCR-SSP) was performed to examine the association of certain alleles or polymorphic sequences of HLA-DRB1 with AIH.

RESULTS: HLA-DRB1 typing by PCR-SSP showed that DR4 had a significantly increased frequency among patients with AIH versus healthy control (46.9% versus 20.8%; relative risk = 3.35, P = 0.014). In subtypes of DR4, there was a trend of increase in the gene frequency of DRB1 *0405 in patients with AIH versus healthy controls (21.9% vs 6.3%, P = 0.04, but P_c = 0.08). In addition, a significant increase was found in the alleles frequency encoding QRRAA from the third hyperpolymorphic region of DR4 in the patients with AIH (86.7% of DR4 positive patients vs 40.0% in DR4 positive controls, P = 0.016, P_c = 0.028, RR = 9.75).

CONCLUSION: AIH in Chinese is associated with HLA-DR4. There is a relationship between QRRAA sequence within the third hyperpolymorphic region of the DRB allele and AIH in Chinese.

Immunohistochemical study of hepatic oval cells in human chronic viral hepatitis

AIM: To detect immunohistochemically the presence of oval cells in chronic viral hepatitis with antibody against c-kit.

METHODS: We detected oval cells in paraffin embedded liver sections of 3 normal controls and 26 liver samples from patients with chronic viral hepatitis, using immunohistochemistry with antibodies against c-kit, π class glutathione S-transferase (π-GST) and cytokeratins 19 (CK19).

RESULTS: Oval cells were not observed in normal livers. In chronic viral hepatitis, hepatic oval cells were located predominantly in the periportal region and fibrosis septa, characterized by an ovoid nucleus, small size, and scant cytoplasm. Antibody against stem cell factor receptor, c-kit, had higher sensitivity and specificity than π-GST and CK19. About 50%-70% of c-kit positive oval cells were stained positively for either π-GST or CK19.

CONCLUSION: Oval cells are frequently detected in human livers with chronic viral hepatitis, suggesting that oval cell proliferation is asso ciated with the liver regeneration in this condition.

Relationship of plasma folic acid and status of DNA methylation in human gastric cancer

To evaluate the anti-cancer effects of folic acid at the molecular level, we determined plasma folic acid concentration by radioimmuno-assay and the degree of total genomic DNA methylation by incubating DNA with 3H-S-adenosylmethionine (3H-SAM) in the presence of a methylase, and analyzed the methylation status of the c-myc and c-Ha-ras oncogenes by Southern blotting in 21 patients with advanced gastric cancer. The degree of total genomic DNA methylation of cancerous tissues was significantly lower than that of paracancerous and non-cancerous tissues; c-myc and c-Ha-ras oncogenes from cancerous (10/21, 5/10) and paracancerous (13/21, 4/10) tissues were hypomethylated. The plasma folic acid concentration in patients who showed hypomethylation was lower than that patients showing normal methylation. These findings suggest that a decrease in folic acid, and the subsequent DNA hypomethylation, may be involved in human gastric carcinogenesis.

The expression of c-myc and c-N-ras in human cirrhotic livers, hepatocellular carcinomas and liver tissue surrounding the tumors

To study the possible role of proto-oncogenes in the multistep process of human liver hepatocarcinogenesis, we have examined the expression of c-N-ras and c-myc in human hepatocellular carcinomas and liver tissue surrounding the tumors as well as cirrhotic livers which are generally considered to precede the formation of human hepatocellular carcinoma. One to four-fold higher expression of the c-N-ras proto-oncogene was observed in twelve hepatoma patients as compared to normal liver. Increased expression of c-N-ras was also observed in liver tissue surrounding these tumors. Eight patients exhibited an apparent higher expression of the c-N-ras oncogene in adjacent liver tissue than in their corresponding tumor tissues. Six human liver cirrhosis patients also exhibited a slight increase in c-N-ras expression. Southern blot analysis demonstrated an amplified c-N-ras sequence in these tissues surrounding the tumors. In the study of the c-myc gene, variable degrees of highly enhanced expression were found in all twelve hepatoma patients as compared to normal liver. The c-myc gene was also expressed in the adjacent liver tissue and in some of the human cirrhotic livers. Our studies give further evidence that the expression of c-N-ras and c-myc proto-oncogenes are involved in the process of human hepatocarcinogenesis.