BACKGROUND: The purpose of this study was to investigate the persistence of
viable Ehrlichia chaffeensis in ADSOL-treated RBCs stored at 4 to 6 degree
STUDY DESIGN AND METHODS: The continuous monocytic cell lines THP-1 and DH8
2 were infected with E.chaffeensis (St. Vincent isolate). Packed RBC units
were inoculated in separate experiments with E. chaffeensis-infected cells
as final concentrations of 8.02 x 10(4) (DH82) and 1.43 x 10(4) (THP-1) inf
ected cells per mi. Aliquots were stored at 4 to 6 degrees C for 1 to 42 da
ys. At selected intervals, nucleated cells from the RBC aliquots were obtai
ned by using a ficoll-isopaque separation procedure. Uninfected DH82 cell c
ultures were inoculated with the harvested nucleated cells or supernatant.
The cell cultures were evaluated for infection by weekly examination of Wri
ght's (Diff-Quik) stained cytocentrifuged slides. PCR amplification was als
o used to test the harvested nucleated cells or supernatant for the presenc
e of E.chaffeensis DNA.
RESULTS: In both types of infected cell lines, E. chaffeensis was reisolate
d in DH82 cells for as long as 11 days from the cellular fraction and for u
p to 5 days from the supernatant fraction. PCR results were positive throug
hout the 42-day testing period.
CONCLUSION: Cell-associated E.chaffeensis remains viable in ADSOL-treated R
BCs stored at 4 to 6 degrees C for at least 11 days. These data suggest tha
t transfusion-acquired infection is possible. Successful reisolation was ac
hieved from the supernatant fraction, which suggests that RBC products trea
ted with a WBC-reduction procedure may still present a risk for transfusion
transmission. No correlation between PCR positivity and viability of bacte
ria was noted.