Determination of immunoglobulin M antibodies against hepatitis B core antigen and hepatitis A virus by reorienting sucrose gradient high-speed centrifugation for diagnosis of acute viral-hepatitis

A two-particle turbidometric latex immunoassay for the detection of specific IgM antibodies

A simple two stage assay using latex particles as a reaction indicator has been developed for the detection of IgM antibodies to Trichinella spiralis. In the first stage, magnetic polystyrene beads (Dynabeads) coated with T. spiralis antigen were incubated for 30 min with the test serum. After washing, in the second stage, the assay was developed for 1 h using anti-mu-coated latex particles. After sedimentation of the Dynabeads the turbidity of the resultant latex suspension was measured spectrophotometrically at a wavelength of 400 nm. A decrease in turbidity of more than 20% from that of the control, unreacted, suspension was considered positive. Using an IgM phosphorylcholine-binding monoclonal antibody which was reactive with T. spiralis, the sensitivity of the assay was determined to be 110 ng/ml of antibody. This was 20-fold less than the sensitivity achieved in an indirect enzyme-linked immunosorbent assay (ELISA). When the assay was applied to sera obtained from CBA/N or BALB/c mice, which were either normal or immunized against T. spiralis, the expected results were obtained with titers up to 1/640 observed, and confirmed (r = 0.93, P less than 0.001) in the ELISA.

Diagnostic significance of anti-HBcIgM prevalence related to symptoms in Canadian patients acutely or chronically infected with hepatitis B virus

A total of 362 sera from 295 Canadian patients were examined for HBsAg, anti-HBs, anti-HBc, anti-HBcIgM, HBeAg, and anti-HBe using commercial immunoassays. Serial samples from 70 acutely infected patients demonstrated that anti-HBcIgM may detect 10% more positives than HBsAg within 4 months after the onset of clinical symptoms, and all except two were negative for anti-HBcIgM after the fourth month. None of 66 asymptomatic (HBeAg rate 18.2%) and two of 14 (14.3%) symptomatic (HBeAg rate 64.3%) carriers of HBsAg were positive for anti-HBcIgM (P = 0.029). Elevated marker responses were measured in two symptomatic carriers for a 20-month period. Anti-HBcIgM was not detected in either 100 asymptomatic patients positive for total anti-HBc, negative for HBsAg and negative for or possessing low levels of anti-HBs, 25 patients with liver disorders not caused by HBV, or 20 healthy milk donors. In diagnostic laboratory practice this anti-HBcIgM test may be useful in the following situations: to supplement HBsAg testing, providing a theoretical 10% increase in positives within 4 months following onset of acute viral hepatitis; to replace testing for anti-HBc and anti-HBs in symptomatic HBsAg-negative patients; to confirm whether a patient is experiencing acute or chronic HBV infection or symptoms superimposed upon asymptomatic HBsAg carriage by another cause, such as nonA-nonB viral hepatitis.

Immunoglobulin M antibodies against hepatitis B core antigen in patients with chronic hepatitis B infection

A batch of sera obtained from subjects with acute hepatitis B virus (HBV) infection, chronic carriers of hepatitis B surface antigen (HBsAg) who were either asymptomatic or who had chronic active hepatitis, and 32 sera from patients with HBsAg negative chronic active hepatitis were examined for the presence of antibodies against hepatitis B core antigen (anti-HBc) by radioimmunoassay (RIA). Sera containing anti-HBc were fractionated on sucrose density gradients to separate immunoglobulin M (IgM) and the titre of anti-HBc IgM was determined. In patients with acute HBV infection, anti-HBc IgM was detected during the acute phase of the illness with titres ranging from 1:128 to 1:4,096 (geometric mean titre 1:709). The titre of anti-HBc IgM fell rapidly over the following months and in most patients persisted at low levels for several years. Anti-HBc IgM was also detected in subjects with chronic HBV infection but with significantly lower titres. In asymptomatic carriers, anti-HBc IgM titres ranged from 1:4 to 1:32 (geometric mean titre 1:12), whilst carriers with chronic active hepatitis had titres ranging from 1:4 to 1:128 (geometric mean titre 1:35). By using a standardized assay procedure, the titre of anti-HBc IgM in a patient's serum may be of value in differentiating between acute and chronic HBV infection.

Prevalence and significance of anti-HBc IgM (radioimmunoassay) in acute and chronic hepatitis B and in blood donors

Anti-HBc IgM was determined by a modified radioimmunoassay (RIA) in 35 patients with acute hepatitis B, 35 patients with chronic hepatitis B (7 with chronic persistent, and 28 with chronic active hepatitis), 157 HBsAg positive blood donors, and in 143 HBsAg negative but anti-HBc positive donors. The results of the RIA test were compared with those obtained by an ELISA technique. In chronic hepatitis, anti-HBc IgM was correlated with the occurrence of HBeAg, anti-HBe, Dane particles in the serum, HBsAg, and HBcAg in liver tissue and with biochemical and histological degrees of hepatic inflammatory activity. In acute self-limited hepatitis B, anti-HBc IgM (RIA and ELISA) was initially positive in all 35 patients. Twelve months after the acute illness, 94% of the patients were negative for anti-HBc IgM in the RIA test with only one patient showing a persistence of up to 18 months, whereas in the ELISA test anti-HBc IgM persisted in 17% of the patients over 2 years. In chronic hepatitis, the occurrence of anti-HBc IgM (RIA) showed a strong relation with the inflammatory activity, the anti-HBc IgM positive patients revealing a significantly more severe liver disease than did anti-HBc IgM negative patients. Anti-HBc IgM (RIA), however, did not correlate with the occurrence of HBeAg and Dane particles in the serum and HBcAg in liver tissue of patients with chronic hepatitis. Of the 157 HBsAg positive blood donors, anti-HBc IgM (RIA) could be demonstrated in 10 (6%), but in none of the 143 HBsAg negative, but anti-HBc positive donors, as compared to 43 (27%) and 9 (6%), respectively, in the ELISA test. Comparing the two test methods, the RIA exhibits higher specificity than did the ELISA due to a better blocking of nonspecific reactions, but possibly somewhat lower sensitivity. In this form, however, the RIA test is a more useful tool in the diagnosis of the different forms of hepatitis B virus infection and in determining the severity of chronic hepatitis B.