Page 2011 - Hematology_ Basic Principles and Practice ( PDFDrive )

1782 Part XI Transfusion Medicine

Cell Blood Cell Apparent volume
type concentration content of distribution

Initial End % Blood b Product c Fraction d Liters No. of blood
change a volumes
CD34
Cells
25 L 0.077 0.045 –45 3.8 7.9 2.3 25.9 5.3
15 L ×2 0.078 0.039 –50 3.9 8.1 2.3 22.2 5.1

a Percentage change, end vs. initial
b Estimated initial content in peripheral blood
c Total product content
d Total product content divided by estimated initial content in peripheral blood. L, liters. CD34 cell
8
9
concentration in 10 /L, CD34 cell content x 10 cells.
Fig. 118.1 TWENTY HEALTHY MOBILIZED DONORS UNDERWENT EITHER A SINGLE LARGE
VOLUME LEUKAPHERESIS PROCEDURE OF 25 L OR TWO CONSECUTIVE-DAY SMALLER
VOLUME PROCEDURES OF 15 L EACH. In both study groups, more than twice as many CD34 cells
were collected than the estimated total content of these cells in the peripheral blood before apheresis, providing
evidence for the existence of a large extravascular pool of peripheral blood stem cells, which becomes accessible
to collection by leukapheresis. (Modified from Bolan CD, Carter CS, Wesley RA, et al: Prospective evaluation of cell
kinetics, yields and donor experiences during a single large-volume apheresis versus two smaller volume consecutive day
collections of allogeneic peripheral blood stem cells. Br J Hematol 120:801, 2003, by permission of the authors.)

100
20
15
80 Platelets
10
% Original component 60 Cell number (relative scale) 9 8 7 6 Lymphocytes

40

20 5 4 3 Other Granulocytes
mononuculear
2 cells
0 1
0 0.5 1.0 1.5 2.0 2.5 3.0
Number of volumes exchanged 0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Fig. 118.2 RELATIONSHIP BETWEEN VOLUMES REMOVED BY
APHERESIS AND PERCENTAGE OF THE TARGET COMPONENT Hemoglobin g/100 mL
REMAINING. The relation is valid for blood volumes during red blood cell Fig. 118.3 SCHEMATIC DISTRIBUTION OF CELLS AT THE COL-
exchange or for plasma volumes during plasmapheresis if the target solute LECTION PORT OF A CENTRIFUGAL CELL SEPARATOR. The
remains primarily within the intravascular compartment. number and percentage of each cell type collected can be varied by adjusting
the site of collection along the interface or by changing centrifugal force,
blood flow rate, or rate of cell removal.
columns selectively remove LDL, very-low-density lipoprotein, and
lipoprotein, and have proved effective in managing patients with
homozygous hypercholesterolemia who have not responded to diet
and cholesterol-lowering drug therapy (Fig. 118.4). A similar tech- Therapeutic Cytapheresis
nique, heparin-induced extracorporeal lipoprotein precipitation, uses
low pH and negatively charged heparin to precipitate lipoproteins Common indications for therapeutic cell removal are listed in Table
and remove the precipitate by filtration online (H.E.L.P. Plasmat 118.1. Most of these procedures entail simple apheresis of the patient’s
Futura, Braun Medical). Apheresis technology has also been adapted peripheral blood with diversion for discarding the affected RBC,
for extracorporeal phototherapy of patient leukocytes (photopheresis) white blood cell (WBC), or platelet fraction. Special apheresis tech-
to treat cutaneous T-cell lymphoma and to modulate the pathologic nologies have been approved, such as photopheresis devices, that
immune response in graft-versus-host disease (GVHD), solid organ divert a cell fraction that is photochemically treated in the extra-
transplant, and autoimmune diseases (see later discussion). corporeal circuit and returned to the patient’s circulation, and