Identification of two determinants included in "antigen" HL-A-10 (TO 31 and TO 40) and of a new family of cross-reacting specificities (HL-A1,11,TO 30,31,40).

A new family of cross-reacting HL—A specificities is described. Sera obtained from a multiparous woman and four polytransfused individuals identify three antigenic determinants belonging to the first HL—A segregant series: TO 30 (gene frequency .0446), TO 31 (gene frequency .0150), and TO 40. Serological, familial, and population analysis shows that (A) the specificities TO 31 and TO 40 are included in HL—A10; (B) TO 30 is probably identical to Ao 28 (from Amos); (C) TO 30, TO 31, TO 40, HL—A1, and HL—A11 are a group of cross-reacting specificities of the first HL—A series.