Effect of storage and ultraviolet B irradiation on CD14-bearing antigen-presenting cells (monocytes) in platelet concentrates.
BACKGROUND
Ultraviolet B (UVB) irradiation of platelet concentrate (PCs) reduces platelet alloimmunization, but the mechanism of the effect is unclear. Evidence suggests that UVB may downregulate the expression of surface adhesion molecules on passenger antigen-presenting cells in PCs.


METHODS
The effect of blood bank storage, platelet preparation from whole blood, and UVB irradiation on the quantitative expression of intercellular adhesion molecule-1 (ICAM-1, or CD54), HLA-DR, CD45, and CD11c on CD14-positive antigen-presenting cells (monocytes) was studied by using two-color flow cytometry.


RESULTS
Blood bank storage for 4 days resulted in upregulation of ICAM-1 and HLA-DR and downregulation of CD14 but left the expression of CD11c and CD45 unchanged. Preparation of PCs from fresh whole blood was associated with a rapid increase in CD11c without upregulation of ICAM-1 and HLA-DR. UVB irradiation before storage inhibited the upregulation of ICAM-1 and HLA-DR, resulted in accelerated downregulation of CD14, and was associated with increased loss of monocytes. Agitation of the PC bag during irradiation was of critical importance, since omission of agitation resulted in largely uninhibited upregulation of ICAM-1 but was still associated with significantly higher cell loss than that seen in unirradiated controls.


CONCLUSIONS
UVB exposure nonspecifically affects monocytes in PCs, resulting in downregulation of surface molecules that are important for antigen presentation, as well as in significant cell loss.
Fiebig
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Department of Pathology, School of Medicine, University of California, San Diego, La Jolla.
Lane
T A
TA
D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000528:radiation effects; D015703:Antigens, CD / Q000032:analysis*; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis*; D001792:Blood Platelets / Q000528:radiation effects*; D001793:Blood Preservation; D006801:Humans; D018950:Lipopolysaccharide Receptors; D009000:Monocytes / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018950:Lipopolysaccharide Receptors