Interferon therapy in paediatric practice: New applications

Interferons were identified in 1957 as antiviral factors produced by cells.' The interferons are a family of proteins divided into three types: interferon alpha, interferon beta and interferon gamma. Interferons bind to cell membrane receptors and can upregulate or downregulate cellular genes. Functional effects of interferons on cells of the immune system include increased cytotoxic cell activity, induction of histocompatibility antigens (interferon alpha and gamma) and activation of cells (interferon gamma).2 In addition, alpha and beta interferons inhibit the growth and differentiation of normal and malignant cells.2 The development of technology enabling production of therapeutic quantities of these interferons by genetic engineering has enabled recent therapeutic advances in paediatrics. Interferon alpha has shown promise in the treatment of haemangiomas of infancy and childhood and interferon gamma has been used in the treatment of chronic granulomatous disease. Alpha interferon had been observed to have a beneficial effect on Kaposi's sarcoma, an AIDS-associated cutaneous disorder with vascular endothelial pr~liferation.~ The observation that alpha interferon inhibits angiogenesis suggested that alpha interferon may also be beneficial in haemangiomas in infancy and in ~ h i l d h o o d . ~ There are now at least 28 published cases in which alpha interferon has been used in infancy and childIn general, these have been either haemangiomas which compromise vital structures such as the airway, orbital and periorbital haemangiomas which threaten vision, or large haemangiomas which result in consumptive coagulopathy and thrombocytopenia or cardiac failure. Of the published cases, 82% (23 out of 28) have been reported to show a beneficial response which can occur within 1 month of commencing therapy. Doses ranged from 1 to 6 x 106 unitsIm2 per day given subcutaneously. The mean duration of therapy for the 28 cases was 9.8 months, and 13 of the 28 subjects were treated for 6 months or less. Twenty-six of the 28 cases had been treated previously with steroids with either an incomplete or no response. Although this appears to be a promising mode of therapy, caution needs to be exercised. It is important to be sure that the condition being treated is a haemangioma and not a vascular malformation. Haemangiomas are characterized by marked