الفهرس 
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Abstract
Hepatitis C virus (HCV) is a major aetiological agent of chronic liver disease worldwide, affecting an estimated 3% of the population. characteristic features of HCV infection include high incidence of persistence in the host and progression to chronic hepatitis, leading to cirrhosis, which is a strong risk factor for development of hepatocellular carcinoma.
In patients with liver cirrhosis, liver biopsy is the traditional gold standard method to establish the diagnosis. However this procedure has many disadvantages, it is invasive, coasty and difficult to standardize. That is why there has been increasing interest in noninvasive assessment of liver cirrhosis by the use of alternative serum markers.
IL-18, previously known as interferon-gamma-inducing factor, is a proinflammatory cytokine that is expressed mainly by peripheral blood mononuclear cells and macrophages. In the liver, besides its expression in Kupffer cells, IL-18 can also be synthesized by injured hepatocytes.
IL-18 plays a strategic role in inflammation through the induction of inflammatory cytokines and chemokines. Besides, IL-18 increases the susceptibility of liver endothelial cells to undergo apoptosis. The fundamental function of IL-18 is an enhancement of Th1 helper cytokine production. Through interferon-gamma (IFN-γ) production, IL-18 augments perforin dependent cytotoxicity of liver natural killer cells and Fas ligand-mediated cytotoxicity of Th1 cells.
The fact that the liver is responsible for IL-18 clearance and excretion into bile may partly explain the increased IL-18 concentrations in cirrhotic and fulminant hepatic failure. An increased circulating level of IL-18 is likely to play a pathogenic role in patients with chronic liver disease.
This study was aiming to evaluate IL-18 as non-invasive marker of the severity of liver damage in chronic hepatitis C patients by estimating its levels in those patients and comparing between them and results of liver biopsy using Child-Pugh score.
The study was conducted at the internal medicine inpatient unit, Laparoscopy unit and clinical pathology department of Suez Canal University Hospital. Study sample was 60 individuals and were classified into three groups: cirrhotic CLD patients’ group, non-cirrhotic CLD patients’ group and normal healthy volunteers group.
The following were done for those patients: history taking ,general examination & abdominal examination and lab work (PT, PTT, INR, ALT, AST, Albumin, AFP, Platelets, Hemoglobin, WBCs and serum IL-18 level using ELISA technique).
By analyzing and processing the data obtained from the history, clinical examination and lab work the study declared that:
According to this study, AFP level was significantly higher in cirrhotic CLD patients’ group than non-cirrhotic CLD patients’ group and control group.
The study also declared that there was a significant difference in IL-18 level between cirrhotic CLD patients’ group (836.5±320.6pg/ml) compared to non-cirrhotic CLD patients’ group (751.5±121.1pg/ml) and control group (278.9±55.2pg/ml) (P˂ 0.05). Also there was a significant difference in IL-18 level between non-cirrhotic CLD patients’ group compared to control group.
from the above data we concluded that:
• IL-18 levels are elevated in chronic hepatitis C patients than in healthy subjects.
• IL-18 level is significantly increased with the increase in the histological stage of liver cirrhosis and its concentration may predict the degree of hepatocellular damage.
• Positive correlation founded between serum 1l-18 levels and Child Pugh score may suggest that IL-18 could be used and nominated as an additional non-invasive marker for monitoring the degree of liver cirrhosis in chronic hepatitis C patients and as a monitoring tool to assess response to therapy.
• Low cut off value of serum IL-18 at 495 pg/ml (which showed sensitivity of 100%, i.e. no false negative results) can be used as a screening value under which all cases are probably negative cases for liver cirrhosis.
• High cut off value of serum IL-18 at 875 pg/ml (which showed specificity of 95%, i.e. only 5% false positive results) can be used as a diagnostic value above which 95% of cases are probably positive cases for liver cirrhosis.