e. All panel cells and autocontrol are positive only in AGT. The subject may
have a warm autoimmune antibody (see Lesson 2, Section I).
f. All cells in the panel negative; autocontrol negative; many cross-matches
incompatible. This may be found when the pre-panel work has not been properly done.
Anti-A1 occurring in a small number of A2 and A2B individuals, produces incompatibility
in approximately 80 percent of crossmatches involving random group A blood (that is,
all A1 or A1B bloods), but does not react at all with the group O cells on the panel.
g. All cells in the panel negative; autocontrol negative; rare cross- match
positive; or cells of infant are incompatible with mother. The serum may contain an
antibody for a low-incidence or familial antibody. Many of the low-incidence antibodies
were first recognized when a newborn, expected to be normal, was born with, or
developed hemolytic disease of the newborn during the neonatal period.
1-36. ANTIBODIES NOT EASILY IDENTIFIED
When the results with the RBC panels do not permit clear identification, the
following should be considered.
a. There are occasions when a panel may have to be other than group O. To
prove a presence of an anti-A1 in a group A2 or A2B, the cells have to be divided
between A1 and A2. If, in addition to anti-H, another antibody is present in the serum of
a group A1-individual, the panel cells would all have to be A1 that have been tested for
the other common antigens.
b. More than one antibody may be present. Look at the reactions of the
antibody with the cells on the panel. Are there differences among the reacting cells in
temperature, suspending medium, or strength of reaction? Do some cells hemolyze?
Are some reactions enhanced or destroyed with enzymes? This may give an indication
of the identity of one or more of the antibodies. Absorption and elution studies may be
used to separate the antibodies. Type the subject's cells to determine their antigenic
composition. Except in autoimmune diseases, antibodies are not present in the
subject's serum if the antigens are on the RBCs. If the cells have a positive DAT,
serums reacting by AGT cannot be used in the routine manner.
Testing should be performed on pretransfusion cells. Circulating donor
cells contribute an assortment of foreign antigens that may be
c. The antibody may be reacting in an unexpected manner. One would not
expect anti-M or anti-P1 to react only by AGT or anti-s to react only at RT, but it could