Immunoassay for quantifying squamous cell carcinoma antigen in serum.

BACKGROUND: Although the benefits of quantifying serum squamous cell carcinoma antigen (SCCa) have been reported, SCCa reagents were no longer available in the US by the late 1990s. Because SCCa quantification still has demonstrated clinical utility, we developed and validated a microtiter plate-based ELISA for measuring SCCa in serum. METHODS: We coated microtiter strips overnight with capture anti-SCCa monoclonal antibody, washed the wells, added blocking buffer, and lyophilized the strips. For detection, we used a biotinylated anti-SCCa detection antibody, streptavidin/horseradish peroxidase conjugate, and tetramethylbenzidine/H(2)O(2) substrate. A novel blocking reagent against human antimouse antibodies (HAMA) was evaluated. A reference interval was established with sera from healthy individuals and was confirmed in smokers. RESULTS: The assay was linear to 40 microg/L SCCa (slope, 1.00; y intercept, 0.695; R(2), 0.996) with a detection limit of 0.3 microg/L. The intraassay imprecision results [mean (CV)] were 2.5 microg/L (3.4%), 18.0 microg/L (3.0%), and 30.7 microg/L (2.4%); interassay imprecision results were 2.0 microg/L (9.9%), 20.0 microg/L (7.6%), and 36.3 microg/L (3.5%). A correlation analysis against an established automated assay generated a slope of 0.976 and a y intercept of -0.193 microg/L (r(2) = 0.916). An upper reference limit of 2.1 microg/L SCCa was established at 95% confidence level, with no difference observed in smokers. No correlation between SCCa concentration and age was observed (r(2) = 0.0003). At a blocking reagent concentration of 5 mg/L, HAMA interference was eliminated in 3 samples known to produce falsely increased SCCa results. CONCLUSIONS: This SCCa ELISA demonstrates acceptable performance characteristics for quantifying serum SCCa and is effective in eliminating HAMA interference.

Treatment of chronic hepatitis C in HIV/HCV-coinfection with interferon alpha-2b+ full-course vs. 16-week delayed ribavirin.

Human immunodeficiency virus (HIV)-infected patients increasingly experience the consequences of chronic hepatitis C virus (HCV) coinfection. This trial randomized 107 patients coinfected with HIV and HCV to receive 48 weeks of interferon alfa-2b (IFN) 3 million units three times weekly plus either a full course of ribavirin (RBV) at 800 mg/day (group A; n = 53) or 16 weeks of placebo, followed by RBV (group B; n = 54). The primary endpoint of sustained viral response (SVR) rate (undetectable HCV RNA at posttreatment week 24) was not different between groups A (11.3%) and B (5.6%; P =.32). Within group A, the SVR rate was lower in genotype 1 (2.5%) than in genotypes 2 through 4 (41.7%; P =.002). Fifty-five patients discontinued therapy prematurely, mostly because of adverse events or patient decisions. At treatment week 12, the percentage of CD4+ cells rose in group A (+4.1%; P <.001), but not in group B (-0.3%). A significant proportion (22%) of patients who were HIV viremic at baseline had undetectable HIV RNA at week 12. By week 16, the hemoglobin level decreased more in group A (-2,52 g/dL) than in group B (-1.02 g/dL; P <.001). In group A, the hemoglobin decline was steeper in patients receiving zidovudine (azidothymidine [AZT], -3.64 g/dL vs. no AZT, -2.08 g/dL), and patients receiving zidovudine had more anemia-related RBV dose reductions (AZT, 60% vs. no AZT, 16%). In conclusion, HCV therapy with IFN plus RBV is relatively safe in patients coinfected with HIV and HCV, but frequent treatment discontinuations and anemia-related RBV dose reductions contribute to a poor SVR rate. Control of HIV infection improves rather than worsens during therapy.