Unexpected results:
(1) The patient has an alloantibody to an antigen that the patient possesses.
(2) The absence of an expected antibody (false or true negative).
(3) The presence of an unexpected antibody. (false or true positive).
(3) The absence of an expected antigen (false or true negative).
(4) The presence of an unexpected antigen (false or true positive).
Factors that may cause a false positive antigen-antibody reaction:
(1) rheumatoid factor
(2) heterophile antibody (reacts with antigens other than primary target antigen)
(3) anti-idiotypic antibody
(4) HLA antibody
(5) antibody to the animal species that has been used for reagent antibody production (anti-mouse antibodies, etc.)
(6) autoantibody
(7) antibody to enzyme-labelled conjugate or other element in the test system
(8) hyperlipidemia
(9) complement activation
(10) cross-reacting antibody
(11) specimen mix-up
(12) polyagglutinin secondary to bacterial contamination
(13) recent plasma transfusion
(14) contaminated reagent
(15) a reagent mix-up
Conditions associated with a false negative antigen-antibody reaction:
(1) immunosuppression
(2) immunodeficiency
(3) hemodilution
(4) starch or other absorbent material
(5) insufficient time for antibody response to develop
(6) prozone effect (very high antibody concentration)
(7) specimen mix-up
(8) problem in the target antigen (species or strain specific)
(9) inactivated reagent
(10) a reagent mix-up
