Antibodies to low-incidence antigens will be difficult to test for since most screen and panel cells do not have these antigens on the testing cells. Further testing may be needed at a reference laboratory where a larger selection of antibody panels are available to locate cells positive for these antigens.

Suspect an antibody to a low-incidence antigen if:

• AHG crossmatch is incompatible and
• Other causes have been ruled out (positive donor DAT, ABO incompatibility)
  

Examples of antibodies to low-incidence antigens are: anti-V, anti-C^w, anti-Kp^a, anti-Js^a, and anti-Lu^a.