Assessment of immune response to meningococcal disease: comparison of a whole-blood assay and the serum bactericidal assay.

A whole-blood assay (WBA), which assesses the complete bactericidal activity of blood, was compared with the serum bactericidal assay (SBA), which measures antibody and complement mediated cell lysis. Twenty children infected with serogroup B strains and 25 infected with serogroup C strains were studied 8-12 weeks after disease, and 29 healthy children were used as controls. The infecting strain (convalescent children only) and two reference strains, MC58 (B:15:P1.7, 16) and NCTC 8554 (C:NT:P1.5) were used. In children previously infected with a serogroup B strain, bactericidal activity was detected in 95% and 85% to their infecting strain by the WBA (>50% killing) and the SBA (s), respectively. Bactericidal activity to the reference serogroup B and C strain was detected by WBA in 70 and 75% of children, respectively, and the SBA in 45% and 20%. In contrast bactericidal activity was detected to both serogroup C strains in >80% of children previously infected with a serogroup C strain using either assay and in 48% (WBA) and 20% (SBA) to the reference serogroup B strain. Levels of bactericidal activity were detectable in fewer control children. Children convalescing from meningococcal disease develop an immune response to their infecting strain, detectable by both the WBA and SBA, which is independent of age. However, the WBA appears to be a more sensitive measure of bactericidal activity to heterologous strains than the SBA.

Humoral immune responses to Neisseria meningitidis in children.

An understanding of the nature of immunity to serogroup B meningococci in childhood is necessary in order to establish the reasons for poor responses to candidate vaccines in infancy. We sought to examine the nature of humoral immune responses following infection in relation to age. Serum bactericidal activity was poor in children under 12 months of age despite recent infection with Neisseria meningitidis. The highest levels of bactericidal activity were seen in children over 10 years of age. However, infants produced levels of total immunoglobulin G (IgG) and IgG subclass antibodies similar to those in older children in a meningococcal enzyme-linked immunosorbent assay. Most antibody was of the IgG1 and IgG3 subclasses. This striking age dependency of bactericidal antibody response following infection is not apparently due to failure of class switching in infants but might be due to qualitative differences in antibody specificity or affinity.

Cellular immune responses to Neisseria meningitidis in children.

There is an urgent need for effective vaccines against serogroup B Neisseria meningitidis. Current experimental vaccines based on the outer membrane proteins (OMPs) of this organism provide a measure of protection in older children but have been ineffective in infants. We postulated that the inability of OMP vaccines to protect infants might be due to age-dependent defects in cellular immunity. We measured proliferation and in vitro production of gamma interferon (IFN-gamma), tumor necrosis factor alpha, and interleukin-10 (IL-10) in response to meningococcal antigens by peripheral blood mononuclear cells (PBMCs) from children convalescing from meningococcal disease and from controls. After meningococcal infection, the balance of cytokine production by PBMCs from the youngest children was skewed towards a TH1 response (low IL-10/IFN-gamma ratio), while older children produced more TH2 cytokine (higher IL-10/IFN-gamma ratio). There was a trend to higher proliferative responses by PBMCs from older children. These responses were not influenced by the presence or subtype of class 1 (PorA) OMP or by the presence of class 2/3 (PorB) or class 4 OMP. Even young infants might be expected to develop adequate cellular immune responses to serogroup B N. meningitidis vaccines if a vaccine preparation can be formulated to mimic the immune stimulus of invasive disease, which may include stimulation of TH2 cytokine production.

Morbidity and mortality in compensated cirrhosis type C: a retrospective follow-up study of 384 patients.

BACKGROUND & AIMS: Few data are available concerning the long-term prognosis of chronic liver disease associated with hepatitis C virus infection. This study examined the morbidity and survival of patients with compensated cirrhosis type C. METHODS: A cohort of 384 European cirrhotic patients was enrolled at seven tertiary referral hospitals and followed up for a mean period of 5 years. Inclusion criteria were biopsy-proven cirrhosis, abnormal serum aminotransferase levels, absence of complications of cirrhosis, and exclusion of hepatitis A and B viruses and of metabolic, toxic, or autoimmune liver diseases. RESULTS: Antibodies against hepatitis C virus were positive in 98% of 361 patients tested. The 5-year risk of hepatocellular carcinoma was 7% and that of decompensation was 18%. Death occurred in 51 patients (13%), with 70% dying of liver disease. Survival probability was 91% and 79% at 5 and 10 years, respectively. Two hundred five patients (53%) were treated with interferon alfa. After adjustment for clinical and serological differences at baseline between patients treated or not treated with interferon, the 5-year estimated survival probability was 96% and 95% for treated and untreated patients, respectively. CONCLUSIONS: In this cohort of patients, life expectancy is relatively long, in agreement with the morbidity data showing a slowly progressive disease.

A double blind, placebo-controlled study to assess the effect of famciclovir on virus replication in patients with chronic hepatitis B virus infection.

This is the first double-blind controlled study of famciclovir, an oral antiviral agent, as potential therapy for chronic hepatitis B virus (HBV) carries. A fall of more than 90% in HBV DNA levels was noted in six of 11 evaluable patients treated with a 10 day course of oral famciclovir. Further studies with more prolonged therapy are ongoing.

Chronic hepatitis C virus infections: predictive value of genotype and level of viraemia on disease progression and response to interferon alpha.

The effects of hepatitis C virus genotype and viraemia on disease outcome in patients with chronic hepatitis C virus infection were studied. Patients infected with genotype 1 tended to develop more severe disease, and to respond less well to interferon (IFN) treatment, but no pretreatment variable successfully predicted either the severity of the disease or the response to IFN. Failure to eliminate the virus during the first three months of therapy, however, predicted a failure to derive long term benefit from the current IFN regime. Hence pretreatment variables cannot be used to determine whether individual patients will respond to IFN, but observations during the first three months of therapy can be used to decide which patients will not respond to prolonged therapy. In these patients consideration should be given to changing the IFN dosing regime or using alternative treatments.