Which of the following statements is true?
1) The patient's red cells, for whom has a positive alloantibody, should be positive for the antigen to which the antibody is directed
2) Agglutination with a panel cell indicates the presence of an antibody to an antigen absent from the RBC
3) Antibody panels can consist of anywhere between 10 - 20 group O donor cells of known antigenic makeup
4) It is preferable to rule out using cells with a heterozygous expression of an antigen