A simple method for collecting nasopharyngeal secretions, using cross-linked dextran.

Local immunological defence mechanisms in the human upper respiratory tract are incompletely defined. This is partly due to the absence of simple and reproducible methods for collecting undiluted secretions. The method described in the present study for collecting nasopharyngeal secretion was simple to perform and exploited the absorbing capacity of dextran, by using filterweave sacs containing dry dextran beads applied locally. The method enabled 100-200 microliters undiluted fluid to be sampled from 15 of 20 healthy volunteers. Measurements of albumin, IgG, IgA and complement factor C3 were performed. The absorption procedure per se was demonstrated not to influence the distribution of these proteins.