Swa: a Subdivision

For some time, anomalous serological reactions have been observed when the same anti-Swa sera are tested against red cells from different individuals reported as Sw(a+). A comparative collaborative study using the same collection of Sw(a+) cells and anti-Swa sera was undertaken by 4 reference laboratories, and it was found that Swa represents a heterogeneous group of antigens that can be subdivided into two categories. Both categories, Sw(a+) 700:41 and Sw(a+) 700:-41, were shown to be inherited.