| Reverse typing is done using known antisera to detect ABO antigens present on the patient's red blood cells. | View Page |
| Red Cells Tested With Known AntiseraSerum Tested With Known Red CellsInterpretation of ABO Group Anti-AAnti-BAnti-A,BA1 CellsB CellsO Cells 04+4+4+00?Using the information provided above, select the correct ABO group. | View Page |
| Red Cells Tested With Known AntiseraSerum Tested With Known Red CellsInterpretation of ABO Group Anti-AAnti-BAnti-A,BA1 CellsB Cells 0004+4+?Using the information provided above, select the correct ABO group. | View Page |
| Red Cells Tested With Known AntiseraSerum Tested With Known Red CellsInterpretation of ABO Group Anti-AAnti-BAnti-A,BA1 CellsB Cells 4+4+4+1+0?Using the information provided above, select the correct ABO group. | View Page |
| Red Cells Tested With Known AntiseraSerum Tested With Known Red CellsInterpretation of ABO Group Anti-AAnti-BAnti-A,BA1 CellsB Cells 4+4+4+00?Using the information provided above, select the correct ABO group. | View Page |
| Table 2: Testing the Patient Red Cells with Known Antisera (Forward Typing) In routine practice, specially prepared blood grouping sera containing anti-A, anti-B, (and optionally anti-A,B) are used to identify the four types of red cells. These sera will agglutinate cells with the corresponding antigen. This is called forward typing. ABO Blood Group Patient Red Cells Tested with Known Antisera Anti-A Anti-B Anti-A,B A 4+ 0 4+ B 0 4+ 4+ O 0 0 0 AB 4+ 4+ 4+ + = agglutination (graded 1+ to 4+)0 = no agglutination | View Page |
| In order to determine the ABO type, known antisera are mixed with patient RBCs and known red cells are mixed with patient serum. | View Page |
| Deducing the Gene The presence of A and/or B antigen on the red cells can be recognized by serological tests with the appropriate antisera so that the presence of the gene that controls its production can be deduced in the absence of both A and B genes (when no A or B antigen is present on the red cells). | View Page |
| Why Knowledge of A Subgroups Is Important For Laboratorians For the most part, subgroups are merely of academic interest, but occasionally they present clinical problems. The antigen may be so weak that it is not detected and the red cells are mistyped as group O. This is especially dangerous if the cells are those of a donor. Problems may arise because the serum of an A2 or A2B, A3 or Ax individual might contain anti-A1. This antibody may be detected in serum typing and cause confusion. You would not expect to find a person with A antigen on his red cells and anti-A in his serum. Anti-A1 is produced by about 1-2% of group A2 persons and about 25% of group A2B persons. Subgroups may be determined by reactions with antisera as seen in the table on the next page. | View Page |
| Reaction of Red Cell Subgroups With Known Antisera Subgroup Patient Red Cells Tested with Known Antisera Anti-A1 in Serum? Anti-A Anti-A1 Anti-A,B A1 4+ 4+ 4+ No A2 4+ 0 4+ Yes, 1-2% A3 2+, mixed field 0 2+, mixed field Yes, but % not available + = agglutination (graded 1+ to 4+)0 = no agglutination | View Page |
| Forward Typing Forward typing is done using known antisera to detect ABO antigens present on the patient’s red cells. In the tube test, known antisera and patient cells are placed in labeled test tubes, centrifuged, and observed for agglutination. Each manufacturer has specific instructions for its own antisera, detailing the percent of cell suspension, number of drops of cell suspension versus number of drops of antisera, and the rate and length of centrifugation. Though the details differ, the theory behind the tests is the same. | View Page |
| Testing the Red Cells With Known Antisera Patient Red Cells Tested With Known Antisera ABO Antigens Present on Red Cell Anti-A Anti-B Anti-A,B 4+ 0 4+ A 0 4+ 4+ B 0 0 0 Neither A nor B 4+ 4+ 4+ A and B + = agglutination (graded 1+ to 4+) 0 = no agglutination or hemolysis | View Page |
| Interpretation of ABO Group We can use the forward type together with the reverse type to interpret the ABO group. The expected reaction are as follows: Red Cells Tested With Known Antisera Serum Tested With Known Red Cells Interpretation of ABO Group Anti-A Anti-B Anti-A,B A1 Cells B Cells 4+ 0 4+ 0 4+ A 0 4+ 4+ 4+ 0 B 0 0 0 4+ 4+ O 4+ 4+ 4+ 0 0 AB + = agglutination (graded 1+ to 4+) 0 = no agglutination or hemolysis | View Page |
| Which of the following statements best describe forward typing? | View Page |
| Which of the following best describes reverse typing? | View Page |