DIRECT COOMBS PANEL

Monospecific coombs is used for testing specimens from adult patients.  Polyspecific coombs is normally used to test samples obtained from infants that are less than six months of age.

COOMBSP

IgG coombs
ANTI-C3b and Anti-C3d

Whole Blood:  3 mL EDTA

0.5 mL

Cord blood

Room Temperature:  Do not store at room temperature
Refrigerated:  2-8^o C for up to 72 hours
Frozen:  Do not freeze

Samples not labeled with complete first and last name and date of birth
Hemolyzed samples

Daily

Same Day

Negative

The Direct Antiglobulin Test (DAT) is used to detect in vivo sensitization of red blood cells.  This sensitization may or may not be associated with shortened red cell survival.  Red cells can become coated with complement because red cell antigen-antibody interactions or immune complexes have activated the complement cascade.  However complement coating does not lead to a visible agglutination reaction.   C3 and C4 are the complement components detected most readily on the red cell.  Of these two, C3 is the most clinically significant.  Complement sensitization can be detected when an antiglobulin reagent containing antibodies to C3b/C3d is used.
 
  The following are some possible causes of a positive DAT:
 
1.  Patient cells are coated with autoantibodies.
2.  Donor cells in patient's circulation are coated with alloantibodies.
3.  Alloantibodies in donor plasma coating patient cells.
4.  Maternal alloantibodies crossing the placenta to coat incompatible fetal cells.
5.  Various drug interactions.