Israel Medical Association Journal

Red cell substitutes are currently under development for use in a variety of surgery and trauma-related clinical conditions. The need for artificial oxygen-carrying fluids continues to be driven by the shortage of donor blood, the complex logistics of blood banking, the risk of virally transmitted diseases, current transfusion practices, and the projected increased demand for blood products in the future. The effort to develop a replacement for the red cell component has evolved over the last century and has presented a number of significant challenges including safety and efficacy concerns. Recent progress in understanding the fundamental interactions of hemoglobin with the body at the molecular, cellular and tissue levels has led to the production of improved red cell substitutes suitable for clinical testing. Currently, seven products are being tested for a variety of applications including trauma, surgery, sepsis, cancer and anemia. Although some of these trials were unsuccessful, the majority of the available products exert no toxicity or only low level side effects. Encouraging results in early clinical trials with oxygen-carrying fluids support further development of these products and have increased the hope that a usable oxygen-carrying fluid will soon be available in the clinic. The purpose of this review is to provide up-to-date information on the status of these products with special emphasis on pre-clinical and clinical experience.

Background: The etiology of bone marrow failure, a prominent feature of paroxysmal nocturnal hemoglobulinuria, is presently unknown.

Objectives: To evaluate the possible influence of cellular immune mechanisms in the bone marrow failure of PNH.

Methods: We studied marrow erythroid colony formation in a patient with paroxysmal nocturnal hemoglobinuria without hypoplastic/aplastic marrow complications.

Results: In vitro assays revealed a pronounced inhibition of primitive erythroid (BFU-E) progenitor cell growth by marrow T lymphocytes. Removal of T cells prior to culture resulted in a 4.5-fold enhancement of BFU-E numbers. Reevaluation of in vitro erythropoiesis during steroid administration indicated a persistent, albeit less prominent, T cell inhibitory effect.

Conclusion: Our findings provide the first direct evidence for a cellular immune inhibitory phenomenon accompanying PNH.

_____________________________ 

PNH= paroxysmal nocturnal hemoglobinuria