[ELISA method using microplates developed with commercial antisera for measuring von Willebrand factor antigen]. / Método ELISA en microplaca desarrollado con antisueros comerciales para medir el antígeno del factor von Willebrand.

The commercial availability of free and peroxidase-conjugated anti-FvW IgG fractions makes it possible to use ELISA methods for FvW: Ag determination in the routine blood coagulation laboratory. A highly sensitive microplate ELISA method was developed in our laboratory (capable of detecting 0.02% FvW: Ag), which proved to be reproducible, quick and not expensive. No significant differences were found between the results attained on different days in 4 control samples (variance analysis), variation coefficient about 12% being observed even for samples with only 11% FvW: Ag. The standard and control sample curves were parallel, which discarded a dilution effect in the assay. The correlation with Laurell's method was r = 0.889 (n = 34, p less than 0.001) and with ristocetin cofactor it was r = 0.677 (n = 19, p less than 0.005).

[Progression to AIDS among HIV-seropositive hemophiliacs]. / Progresión a SIDA en hemofílicos seropositivos frente al VIH.

PURPOSE: To assess the incidence of AIDS, along with its origin and mortality rate, in a group of sero-positive haemophiliacs with long follow-up. MATERIAL AND METHODS: The progression into AIDS in 94 HIV-seropositive haemophiliacs (88 with haemophilia A and 6 with haemophilia B) followed since 1986 has been analyzed. The mean age was 19 years and 64% of the patients had severe haemophilia. All of them had been previously treated with non virus-inactivated factor concentrates. Was detected HIV antigen in 13 of them and 32 were treated with zidovudine. Actuarial analysis started from seroconversion date or from the first positive result and the average observation time was 90 months (5-97). RESULTS: Sixteen patients developed AIDS, resulting in an eight-years accumulative actuarial indice of about 24%. AIDS incidence was lower (p less than 0.0001) in haemophilia A (21%) than in haemophilia B (67%). The eight-years progression rate to AIDS showed a significant dependence on patient age, it being higher in patients aged greater than 30 (77%) than in those aged 15-30 (30%) and less than 15 (9%). Patients who presented CD4+ counts lower than 0.5 x 10(9)/L or CD4/CD8 ratios lower than 0.5 at the beginning of the observation period had a greater 8-year AIDS incidence (63% and 57% respectively) than the remaining patients (16% and 12%). At AIDS diagnosis, all patients had CD4+ lymphocyte counts lower than 0.2 x 10(9)/L, two had detectable HIV antigenaemia and six had been previously treated with zidovudine. The cause of AIDS was an opportunistic infection in all the cases namely, P. carinii pneumonia and candidiasis, but no secondary neoplasia was registered. Nineteen patients died during the follow-up, 12 because of AIDS and 7 because of other reasons unrelated to HIV-infection. CONCLUSION: Our results suggest that 25% of the haemophiliacs will develop AIDS eight years after seroconversion, and a decreasing incidence is not observed. Lower progression rate to AIDS in children than in adults is confirmed.