(5) The technique is the same as for the cold panel. Washed, fresh cell
samples should be used in a 2 percent to 5 percent saline suspension.
(6) Table 1-9 classifies the reactions of some cold antibodies using a
special panel.
Cells
Unknown
^1
^1
Adult
Cord
Auto
Interpretation
Serum
O
O
Control
1.
0 or W+
+++
++++
++
0 or W+
Anti-H
2.
++
++
++
0 or W+
0 to ++++
Anti-l
3.
0 or W+
++
++++
0 or W+
0 or W+
Anti-lH
4.
0 or W+
0 or W+
0 or W+
+++
0 or W+
Anti-i
Table 1-9. Identification of antibodies with a special panel of cells.
(7) Adult i cells should be used in addition to cord cells, if available. Cord
cells also have weak expressions of Lewis, Sda, Chido, and may have very weak P1
antigens. A serum failing to agglutinate cord cells cannot reliably be called anti-I, until
these antibody specificities have been eliminated.
1-39. TITRATION
a. Background.
(1) Titration is a semi-quantitative means of measuring the amount of
antibody in a serum. Serial dilutions (usually two-fold) of antibody are tested with a
constant volume of RBCs, and the result is expressed as the reciprocal of the highest
dilution, at which agglutination is observed. This is usually a macroscopic observation,
but in techniques such as those used in high-titer, low-acidity testing, it is microscopic.
(2) The physical-chemical properties of the antibody, of the reaction
conditions, and of the reagent cells can all influence the results. Therefore, these
variables must be standardized as carefully as possible. Because of its
semi-quantitative nature, titration is most useful in comparing one serum with another
rather than attempting to provide absolute information. Titration is most often used to
demonstrate changing amounts of antibody during pregnancy; however, it is most useful
when comparing one serum against several cell samples to clarify differences between
alloactive, and autoactive antibodies in a serum (for example, identifying anti-I activity or
in identifying "least incompatible" donor units) when crossmatch difficulties exist.
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