USE OF INTRAVENOUS IMMUNOGLOBULINS IN HEMATOLOGICAL DISORDERS

With many controlled clinical trials and well documented case reports, therapy with intravenous immunoglobulins (IVIg) is now used as a majo r or adjuvant therapeutic modality in a great number of haematological diseases, Immune-mediated peripheral cytopenias with severe clinical complications may require instantaneous improvement and, generally, th e response to high doses of IVIg is more rapid than that to corticoste roids, As a rule, the acute forms of idiopathic thrombocytopenic purpu ra (ITP) respond more consistently than the chronic forms, in which th e response to IVIg is more transient. The immunopathogenic mechanisms leading to cytopenia crucially influence the response; for example, IT P due to HIV infection is more resistant to IVIg than acute ITP due to other viral infections or the purely idiopathic forms. Diseases with overt humoral autoimmunity against blood cells and/or against their pr ecursors probably respond to IVIg because of antibody species containe d in the preparations which act at various levels of disturbed immunit y. Important activities of IVIg with therapeutic potential include: (a ) downregulation of the multifaceted Fc receptor function; (b) deviati on of complement activation to innocuous targets; (c) inhibition of au toantibody activity through V region-dependent interaction between the rapeutic and recipient immunoglobulins; and (d) regulation of disturbe d cytokine networks. In addition to its direct action on basic autoimm une processes, IVIg is also used for malignant haematological diseases . In these situations, we use IVIg not to treat the basic disease, but to improve disease-specific and/or iatrogenic immunodeficiency. Thus, patients with lymphoproliferative disorders, if subject to repeated i nfectious episodes, may benefit from long term therapy with the antimi crobial antibodies contained in IVIg. Similarly, patients treated with long term plasma exchange often need IVIg to correct the postpheresis syndrome of hypogammaglobulinaemia if IVIg is not given in higher dos es in combination with plasma exchange for a synergistic effect. Haema tologists should be aware of the costs and potential adverse effects o f IVIg therapy. IVIg costs $US30 to $US50 per gram, depending on the p reparation in use. A few reported cases of virus transmission were con fined to insufficiently controlled production batches, and this much-f eared adverse effect of blood products virtually does not apply to mod ern IVIg preparations. However, IVIg must be administered with caution to patients with cardiovascular and/or renal problems.