Anti-KANNO: A Novel Alloantibody Against a Red Cell Antigen of High Frequency

We encountered a broadly reactive red cell alloantibody in 1991, reacting unlike any other known antibody, and named it anti-KANNO after the first patient. A total of 28 cases of anti-KANNO in the Japanese literature were reviewed. To distinguish KANNO from other antibodies against high-frequency antigens, including anti-JMH, anti-Ch/Rg, and anti-Jra, we conducted serologic studies with proteolytic enzyme and chemical treatments, complement sensitization against red cells, and serum neutralization techniques. Reactivity of anti-KANNO against red cells lacking high-frequency antigens and antisera to high-frequency antigens against KANNO cells were tested. Among the 28 patients, 26 were female, of whom 25 had a history of pregnancy. Red cells from patient KANNO were reactive with antisera against antigens of high frequency. Anti-KANNO reacted weakly with all cells known to lack high-frequency antigens. It reacted with 2-aminoethylisothiouronium bromide, so it can be distinguished from anti-JMH. Differences among anti-KANNO, anti-Ch/Rg, and anti-Jra emerged with enzyme-treated cells, complement-sensitized cells, and the addition of normal serum. As yet, there are no reports of hemolytic transfusion reaction or hemolytic disease of the fetus and newborn attributable to anti-KANNO. It appears that anti-KANNO is a newly characterized antibody more likely stimulated by pregnancy than by transfusion and with little or no clinical significance. Further surveillance and investigation of anti-KANNO, its antigen biochemistry, and its genetics are warranted.