IMMUNOLOGICAL ASPECTS OF HEMODIALYSIS

Haemodialysis patients run an increased risk of infection, which is du e in part to a high incidence of infections related to the vascular ac cess. The increased susceptibility to infections has also been attribu ted to the depressed immune responses demonstrated in experimental stu dies of uraemia. Disturbances in the function of immunocompetent cells and clinical aspects of the immune disorder in haemodialysis patients are reviewed in this article. A number of cellular dysfunctions have been demonstrated in uraemia: the phagocytic function of monocytes and neutrophils is impaired, B and T cell responses to various stimuli ar e decreased in vitro, and disturbances in the production of cytokines have been demonstrated. The immune status and responses of individual patients with chronic renal failure may be altered by several factors. Malnutrition is common and increases the risk of infectious complicat ions, multiple blood transfusions impair T cell functions and can be a source of hepatitis B and C virus infection, iron overload increases the susceptibility to infections with Yersinia enterocolitica and List eria monocytogenes, and the nasal carriage of Staphylococcus aureus pr edisposes to staphylococcal infections. Haemodialysis with cellulosic membranes induces activation of the immune system and may be a factor in the pathogenesis of dialysis-related amyloidosis. Anaphylactic reac tions may be caused by the interaction of blood with the dialysis memb rane or the dialysis device. In conclusion, the pathogenesis of the im mune disorder in dialysis patients is multifactorial. In the future, i mmunomodulating agents may be available to enhance the immune response . However, the only recognised therapy today is preventive treatment o f factors that have negative effects on immunocompetence. Haemodialysi s-associated anaphylactic reactions can be prevented, but other effect s of the blood-dialysis membrane interaction on immune function requir e further investigation.