The usual source of hemopoietic stem cells for transplantation is the bone marrow. However, evidence in rodents, canines, and nonhuman primates indicates that stem cells with marrow repopulating ability also circulate in the peripheral blood. l-4 To use the circulating blood as the primary source of stem cells to repopulate an aplastic bone marrow is a concept that reflects the physiological pattern in which fetal hemopoiesis develops. The fetal bone marrow becomes a site of hemopoiesis after pluripotent hemopoietic stem cells immigrate into its stromal matrix via the circulating blood. Thus, transfusing blood-derived stem cells in adults may be considered to repeat the prenatal seeding of hemopoiesis into the bone marrow. 5.6 In man, the repopulating ability of circulating stem cells is less well established. Goldman et al. 7 were the first to show that blood-derived hemopoietic stem cells can reestablish hemopoietic function after myeloablative treatment for blast crisis in chronic myelogenous leukemia (CML). However, in these patients most stem cells collected and eventually

Two different groups of healthy donors underwent thrombopheresis either with continuous (CS-3000) or intermittent (Haemonetics-30) flow centrifugation systems. Determinations of β-thromboglobulin, Factor XII, Factor XI, Prekallikrein, Kallikrein Inhibitor and High Molecular Weight Kininogen, were carried out at 0, 60 and 120 min after the onset of the procedure. All the contact phase factors remained unchanged during the whole procedure in both groups of donors. β-Thromboglobulin plasma levels increased significantly in the two systems; the overall percentage increases were significantly higher in the CS-3000 donors when compared with those in the H-30 donors.

The best apheretic approach to myasthenia gravis is the selective removal of antiacetylcholine receptor antibodies (antiAchR-Ab) from plasma. A new tryptophan-linked polyvinyl-alcohol gel recently reported to be able to adsorb IgG autoantibodies semiselectively from plasma was investigated in vitro. A consistent reduction of antiAchR-Ab ranging from 76% to 100% was observed in all plasma samples tested. Various degrees of reduction of other immunoglobulins were noted. The regeneration of the immunocolumn did not reduce the efficiency in autoantibody removal. Further in vitro and in vivo investigations are needed to confirm the clinical usefulness of this promising apheretic approach to myasthenia gravis.

While the benefits of automated plasmapheresis have been described, little data is available to compare it to manual plasmapheresis. We therefore compared standard manual techniques (MP) with three automated devices (AP), Haemonetics ® Models V50 and PCS, and the HemaScience Autopheresis-C ™ (HA). Plasma protein concentrations were 56 ± 4 g/L for MP, 63 ± 2 g/L for the V50, 59 ± 5 g/L for the PCS and 63 ± 5 g/L for the HA. Factor VIII recoveries averaged 105 ± 23 U/dL for the MP, 91 ± 18 U/dL and 125 ± 25 U/dL for the V50 (PPP and PRP modes) 95 ± 27 U/dL for the PCS and 121 ± 22 U/dL for the HA, showing a statistically significant difference ( P < 0.05) between manual and automated procedures. Percentage recovery of activity in the cryoprecipitate was similar, giving 337 ± 80 U or 63% for MP, 262 ±70 U or 57% for V50, 252 ± 60 U or 57% for PCS and 367 ± 110 U or 59% for HA. The plasma from MP and HA contained relatively few cells with 12 ± 5 × 10 9/L and 6 ± 1 × 10 9/L platelets; the V50 plasma (PPP mode) contained an average of 103 ± 4 × 10 9/L platelets whereas the PCS plasma had 51 ± 22 × 10 9/L. β-Thromboglobulin levels were significantly elevated in the plasma from the V50. Automated procedures took only 30–40 min whereas the manual procedures took a minimum of 2 hr. While different economic factors will affect the choice of methodology, there is considerable benefit to the use of certain automated devices rather than the widely used manual method for the collection of plasma.

The morphologic alterations of progressive posterior uveitis observed in the chorioid, retina, and subsequently in the vascular system are generally controlled by hemorheologic and/or anti-inflammatory/ immunosuppressive drug therapy. Plasma exchange therapy using 5% serum albumin or serum preserve also appears to be indicated if these conventional treatments do not suffice and if side effects of the drugs applied limit their efficacy, as has been shown from the experience of 22 patients treated. The mechanisms discussed are: elimination of an underlying pathogenic substance, immunomodulatory effects of the plasma exchange fluids, and an improvement of the blood rheology. Further work needs to be done to evaluate the different variables under consideration.

The extent and degree of coronary atherosclerosis may be assessed by indirect parameters and by direct angiographic measurements. Determinations of the hemodynamic significance and properties of coronary stenoses by classical fluid dynamics, and semi-quantitative evaluation of regional hypoperfusion or abnormalities of metabolism and of regional contractile performance are indirect parameters, that do not provide precise information on progression or regression of coronary atherosclerosis. To obtain reliable and reproducible angiographic measurements of coronary stenoses, angiographic pitfalls (film exposure and processing as well as distance of the patient to x-ray tube and image intensifier must be constant, pincushion distortion must be compensated for, standard reference must be used), physiological variables (respiratory and cardiac cycle and coronary vascular tone must be identical on repeat films, slitlike stenoses must be visualized in different projections), and problems with the measurement procedure itself (reproducibility is important, inter- and intra-observer variability must be minimized, stenosis dynamics and plaque volume can only be quantitated by a computer system) have to be overcome or be compensated for. Using a standardized angiographic protocol, we were able to follow progression and regression in a cohort of 10 patients with familial hypercholesterolemia IIa, who were successfully treated with long-term specific LDL-cholesterol immunoabsorption (LDL-apheresis), that favorably influenced the long-term atherosclerotic activity in the coronary arteries of these patients.

We used the Fenwal CS-3000 cell separator to harvest units of neocytes for transfusion in patients with chronic hemolytic anemia. Neocyte enrichment was evaluated by reticulocyte count. These units were contaminated by a large number of leukocytes. In order to minimize immunization to HLA-antigens, these cells could be eliminated by an additional freeze-thaw-wash procedure. To determine the clinical effectiveness, four patients were transfused with neocyte concentrates over a period of six months. This study fails to show a significant benefit of neocyte transfusion, although there was a trend in terms of transfusion requirement.

Loiasis is endemic in the tropical rain forest of Central and some parts of West Africa and is transmitted by the insect vector Chrysops silacea and Chrysops dimidiata. Loa loa infestation causes local inflammation due to migrating adult worms in the subcutis (Calabar swelling) and in the conjunctivae (eye worm). The diagnosis is made by the demonstration of circulating blood microfilariae, the larvae of the adult worms. Since the density of the microfilariae is very low, they can only be identified by concentration methods, such as hemofiltration. During treatment with the specific antiparasitic drug (diethylcarbamazine, DEC), side effects such as allergic reactions due to the rapid disruption of circulating microfilariae may occur. Those symptoms are aggravated in patients with a high number of larvae, leading to meningo-encephalomyelitis or even death. 1 Since microfilariae accumulate in the buffy coat during leukocytapheresis, 2 it was thought that this technique might be a suitable tool to reduce the parasite load and to bypass the side effects of specific drug treatment. Muylle et al. achieved apheresis of microfilariae in two patients with Loa loa infestation by using a Haemonetics, M-300 blood processor. 3 The authors studied two patients with an excessive microfilarial count in the peripheral blood of up to 9/μL and achieved a high enrichment by discontinuous-flow centrifugation. A similar observation was reported by Saeed et al. later on. 4 We have studied two patients with loiasis and report the results of microfilarial apheresis using a continuous-flow IBM/Cobe cell separator.