Chloroquine removal of HLA antigens from platelets for the platelet immunofluorescence test.

Chloroquine-treated platelets did not react with HLA antisera in a platelet suspension immunofluorescence test (PSIFT), while the reactions with platelet-specific antibodies (P1A1, Baka) seemed even stronger after treatment. The method might be useful in discerning HLA and platelet-specific antibodies without absorption procedures. The treatment causes death of a proportion of the cells, with nonspecific fluorescence making the reading difficult. This may be circumvented by using special phase-contrast lenses.