Birgitta Versluijs

117 Respiratory virus infection pre-HCT and alloimmune-mediated lung syndromes A B Days after HCT Days after HCT FIGURE 1. A: Cumulative incidence of allo-LSs for patients with negative RV results, positive BAL fluid RV results, and positive NPA-only RV results. B: Cumulative incidence of allo-LSs for patients with negative RV results and both those with and those without rhinovirus (from BAL fluid only, without taking NPA results into account). Discussion To our knowledge, this is the largest study analyzing the association between detection of RV DNA/RNA before pediatric HCT and the development of allo-LSs. We noted a very high incidence of RV in pre-HCT samples (61%), predominantly rhinovirus. Despite im- munosuppressive treatment of the conditioning and GVHD prophylaxis, no progression to viral pneumonitis occurred. After a median of 8.5 weeks, often coinciding with T-cell immune recovery, 13% of all included patients had respiratory symptoms fitting the diag- nostic criteria for allo-LSs. With the limitations of a retrospective cohort study taken into account, our data suggest that detection of RV in BAL fluid (and not from NPAs) before HCT is a strong predictor for the development of allo-LSs in children after HCT. No dif- ference in effect was found between the various viral species detected, nor did we see a relation with the PCR Ct value (as a semiquantitative measure for viral load) of the virus at detection. Grade II to IV aGVHD in another organ occurring earlier in time (median onset after 6 weeks) appears to have a protective effect on the occurrence of allo-LSs, BAL RV POS  26% (±5) RV POS  6% (±3) NPA-only RVPOS  3% (±3) non rhinovirus POS 28% (±8) rhinovirus POS 24% (±7) no RV 5% (±2) p=0.005 NS 7 1,0 0,8 0,6 0,4 0,2 0,0 0 100 200 300 400 500 0 100 200 300 400 500