I may well be being very thick here, but what exactly is a reference range for an antibody screen? Is it how many positive results you would expect on samples from individuals who are new to your own institution? If it is, and I am not being completely stupid (I probably am), how can ANYONE possibly come up with such a range?
Surely, such a range depends upon al sorts of different factors, such as sex (women who have been pregnant are almost bound to have more atypical alloantibodies than either women who have not been pregnant, or males (who have never been pregnant), individuals who have been multiply transfused because of such things as Sickle Cell Disease, or thalassaemia, but even then, the atypical alloantibodies detected in such individuals depends upon factors like how many transfusions they have received, whether the donors are of the same/similar ethnicity as the individual, and, indeed, whether or not the individual is a respondent or not (or, as the great Dr/Prof Ed Snyder once lectured the British Blood Transfusion Society (BBTS) concerning patient's who have a "virtual transfusion" (they are shown a photograph of a red cell and, as a result, form an atypical alloantibody).
There are just so many variables, I cannot see how there could possibly be a "reference range", unless, as I suspect, I have got completely the wrong end of the stick/