Reactivity of HLA typing sera against cultured lymphoblastoid cell lines and purified peripheral B and T cells from the same original donors.

Anomalous cytotoxicity reactions are observed in some HLA typing sera when cultured lymphoid cells are used as targets. These extra reactions are also detected when the purified B cells from the original donors of the cell lines are used. This observation strongly indicates that these extra reactions are directed to the B cell alloantigens which are normally expressed on B cells of the original donor.