I Chalikonda | PubMed Health

PubMed1997

Immunoprecipitation and virus neutralization assays demonstrate qualitative differences between protective antibody responses to inactivated hepatitis A vaccine and passive immunization with immune globulin.

Antibodies to hepatitis A virus (anti-HAV) were measured in children from two separate vaccine trials (n = 70) 4 weeks after a dose of inactivated hepatitis A vaccine (VAQTA). The geometric mean titers (GMTs) of anti-HAV were 49.3 and 45.2 mIU/mL by immunoassay, while reciprocal GMTs of neutralizing anti-HAV were 6.5 and 15.0 by an 80% radioimmunofocus inhibition test (RIFIT) and 55.6 and 92.0 by antigen reduction assay (HAVARNA). The GMT of antibody detected by radioimmunoprecipitation (RIPA) was > or =401. These data establish serologic correlates of protection against disease and show that RIPA is most sensitive for detection of early vaccine-induced antibody. Sera collected from adults (n = 20) 7 days after administration of immune globulin contained similar antibody levels by immunoassay (45.1 mIU/mL) and slightly higher GMTs of neutralizing antibody (27.5 by RIFIT and 146 by HAVARNA) but negligible precipitating antibody (GMT, 5.6). These results are best explained by differences in the affinity of antibodies for virus following active versus passive immunization.

Adult↗

PubMed1990

Correlation of protein kinase C translocation, P-glycoprotein phosphorylation and reduced drug accumulation in multidrug resistant human KB cells.

Treatment of drug-resistant human KB carcinoma cells (KB-V1) with 0.2 microM phorbol 12-myristate 13-acetate (PMA) resulted in increases of 4-fold in both membrane-associated protein kinase C activity and phosphorylation of P-glycoprotein. The response was essentially complete after 30 min and was relatively stable, since both of these parameters remained elevated above basal levels in cells exposed to PMA for 24 hours. In contrast, long-term PMA treatment of drug-sensitive KB-3 cells caused complete depletion of protein kinase C. The rate of accumulation of [3H]vinblastine in KB-V1 cells was 0.8 +/- 0.1 pmol/mg/30 min in the absence, and 1.9 +/- 0.2 pmol/mg/30 min in the presence, of 20 microM verapamil. Preincubation of cells with PMA resulted in a time-dependent decrease, up to 60% after 24 hours, in both of these values. These results suggest that protein kinase C mediated phosphorylation stimulates the drug transport activity of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗