Chapter 6 - Serologic Investigation of Unexpected Antibodies

Abstract

Infants less than 4 months of age usually do not make antibodies, and if antibodies are detected, they are generally passively acquired from the mother. Several methods are utilized to detect unexpected antibodies in patient's serum/plasma. A variety of special techniques may be performed to resolve serologic problems. Typing (phenotyping) a patient's red cells with antisera of known specificity to determine if the individual possesses or lacks an antigen provides useful information. Phenotyping is most often used to confirm antibody specificity identified in a patient serum. The direct antiglobulin test (DAT) detects IgG and/or complement (C3) coating of the patient's red blood cells in vivo. Elutions are performed to determine specificity of antibody coating the patient's red blood cells. There are two common elution methods used. For antibody evaluations cold-reactive antibody evaluations are the most common antibody workups performed in the pediatric setting. The newest approach to determining if a patient has made additional antibodies is to only do the antibody screen.