[Efficiency of the extraction method with saline dextran in the pp65 antigenemia assay against human cytomegalovirus].

BACKGROUND

To prospectively evaluate the efficacy of the saline dextran extraction method in the human cytomegalovirus (CMV) pp65 antigenemia assay (Ag-pp65).

MATERIAL AND

METHODS

In a 2 months period we studied all the blood samples from immunodepressed patients. The extraction of leukocytes polymorphonuclear (LPMN) was obtained with a 6% dextran solution in 0.9% saline. The total leukocytes population was counted and the percentage of LPMN obtained was established. Simultaneously the LPMN were cultivated into the MRC-5 cell line by the shell vial method (SVC).

RESULTS

The 144 blood samples studied were divided in three groups depending of the positivity in the pp65-AG and/or in the SVC. The patients with both assays positive presented the lower overall leukocyte and LPMN counting, with a difference statistically significance with the pp65-Ag negative. No statistically difference was observed in the overall count of leukocytes in the pp65-Ag negative group. The overall percentage of LPMN obtained was 87%. The median value of pp65-Ag positive samples was 48/100,000 LPMN, this value would be 51/100,000 LPMN with the application of the real percentage of LPMN obtained (p > 0.05).

CONCLUSIONS

The saline dextran extraction method presented a high efficacy in the majority of blood samples studied. The immunological status and the presence of a CMV infection or disease in the patient were the principal factors that influence the extraction method. In general there is no need to adjust the pp65-Ag value obtained with this method to the real one.