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The Caltag Fetal Hemoglobin Test, containing either FITC, R-PE or TRI-COLOR® conjugated monoclonal antibodies to fetal hemoglobin (hemoglobin F), is intended for the identification followed by enumeration of fetal red blood cells. Fetal red cells are identified by the presence of fetal hemoglobin by a flow cytometric method. Fetal cells, when found in the maternal circulation, may be an indication of fetal or maternal complications. The hemorrhage of Rh+ fetal blood into Rh- maternal blood may result in the formation of sensitizing Rh antibodies in the mother. This Rh immunization may be prevented by the administration to the mother of Rh immune globulin (RhIg) soon after delivery. The Caltag Fetal Hemoglobin Test may be used as an aid in detecting incompatible fetal-maternal hemorrhage and determining the need for immunoprophylaxis with Rh immune globulin.

An anticoagulated peripheral blood sample is drawn from an appropriate donor. The erythrocyte count is determined and adjusted, followed by brief fixation of the cells in gluteraldehyde. Fixed and washed cells are permeabilized with a detergent in a manner that is frequently used to enable macromolecules such as monoclonal antibodies to penetrate cellular membranes. Caltag HbF FITC, HbF R-PE and HbF TRI-COLOR monoclonal antibodies bind to fetal hemoglobin in fetal red cells. To identify cells containing fetal hemoglobin, fixed and permeabilized cells are incubated with the monoclonal antibody, and washed to remove unbound antibody. Antibody stained cells are subsequently analyzed by flow cytometric methods. Positive and negative control samples must be used with sample analysis, to establish that all reagents are performing in a consistent manner and that the positive fluorescence attributed to antibody-stained fetal red cells is differentiated from unstained normal red blood cells, leukocytes and any cellular debris. If cord blood is not available for the performance of positive controls, the assay cannot be performed reliably. The recommended positive control samples consist of both 1% and 5% fetal erythrocyte-containing placental cord blood in normal adult blood. The recommended negative control sample consists of 1% anticoagulated sample from a normal male or non-pregnant adult female.