Platelets acquire a secretion defect after high-dose chemotherapy

Article Abstract:

Hemorrhagic myocarditis (inflammation of the heart muscle associated with bleeding) is a potential complication of high-dose chemotherapy and autologous bone marrow transplantation (from self) that may result in tachycardia (rapid heart rate) or severe cardiac failure (ineffective pumping action of heart) and death. Since chemotherapy affects virtually all cells in the body to some degree, it is difficult to attribute this side effect to a particular cause. Nonetheless, it seems worthwhile to investigate platelet changes, which occur after high-dose chemotherapy and might, in some way, contribute to hemorrhagic myocarditis. (Platelets have a role in blood coagulation.) Platelet function was extensively examined in blood samples obtained from 10 patients during and after high-dose chemotherapy. Secondary aggregation or clumping of platelets, which normally occurs in response to ADP (adenosine diphosphate), arachidonic acid, and U44619, failed to occur in all patients after chemotherapy. This observation suggests that the storage pool of ATP (adenosine triphosphate) may be deficient in these platelets. However, examination with the electron microscope showed no decrease in the dense platelet bodies as might be expected. Tests showed that the platelets were capable of releasing ATP, but in reduced quantities. The platelet defect may be one of secretion rather than production. The increase in bleeding time in these patients was only 20 percent, which is not in itself clinically significant. However, there may be other significance to the observed defect in platelet function, aside from increased bleeding time. It may be possible to use tests of platelet function to devise chemotherapeutic protocols less harmful to platelets, and, perhaps, less likely to result in hemorrhagic myocarditis after autologous bone marrow transplantation. (Consumer Summary produced by Reliance Medical Information, Inc.)

Blood platelets, Chemotherapy, Myocarditis

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Intravenous immunoglobulin in bone marrow transplantation

Article Abstract:

Bone marrow transplantation has moved rapidly from an experimental treatment to an accepted clinical procedure. However, the technique has many complications. Infection with cytomegalovirus (CMV) is common in bone marrow recipients as are many other infections. Transplanted bone marrow may induce symptoms of autoimmune disease. A very common complication of bone marrow transplantation is graft-versus-host disease (GVHD), in which the immune cells in the bone marrow attack the apparently foreign cells of the marrow's new host. One treatment method that might affect each of these possible complications and improve the success of bone marrow transplantation is intravenous immunoglobulin (IVIG) therapy. In this treatment, purified antibodies from pooled donor blood are injected to supplement the patient's own antibodies circulating in the blood. Studies have shown that IVIG reduces the incidence of cytomegalovirus interstitial pneumonia. Curiously, however, the IVIG does not actually decrease the incidence of CMV infection, so it must work by modifying the course of disease. Immunologists remain uncertain of how the treatment might accomplish this. GVHD may occur in as many as half of bone marrow transplant recipients. This potentially fatal complication is more common when the tissue types are not closely matched. In two studies of cytomegalovirus infection, researchers observed that the patients receiving IVIG suffered fewer incidents of graft-versus-host disease. Although the evidence indicates that IVIG provides benefits for bone marrow transplant recipients, little is known about the mode of action of IVIG, and little is known about how IVIG might fit in best with other modes of therapy. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Prevention, Cytomegalovirus infections, Immunoglobulins, Intravenous therapy, Antibodies

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Cutaneous and mucosal neoplasms in bone marrow transplant recipients

Article Abstract:

Different types of tumors have been reported to occur after bone marrow transplantation. In general, these tumors may be grouped into three categories: recurrences of leukemia, lymphoproliferative disorders usually positive for Epstein-Barr virus, and unrelated tumors not of blood origin. Of the third group, tumors of the skin or mucosa inside the cheek have been reported only once. In long-term follow-up of 56 survivors of bone marrow transplants, three such tumors were seen. Two were squamous cell carcinomas, one of the skin and one inside the cheek. The third was a malignant melanoma. All three tumors occurred in areas where the patient had experienced graft-versus-host disease following the transplantation. Unfortunately, the small number of cases does not permit identification of a common cause for these tumors, but it should be noted that no such malignancies were observed in 200 patients who had received bone marrow transplants for noncancerous diseases. Skin cancers have been reported as a side effect of defective immunity or prolonged immunosuppression. A combination of factors resulting from immunosuppression and chronic inflammation may have promoted the development of tumors in these patients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Skin cancer

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