Treatment of HCV infection with interferon alpha-2b and ribavirin in a patient with X-linked lymphoproliferative syndrome

Cytokine immunomodulation for the treatment of infectious diseases: lessons from primary immunodeficiencies

Traditionally, management of infectious diseases focuses on identification of the causative microbe and the use of pathogen-targeted therapy. With increasing antimicrobial resistance, novel approaches are required. One strategy is to modulate those natural host immune responses that critically mediate resistance to specific microbes. Clinically, this host-directed tactic could be used either alone or in combination with antimicrobial therapy. While conceptually attractive, there is potential concern that the pathways governing host resistance to pathogens in animal models may not extrapolate linearly to humans. Targeting these immune processes clinically may precipitate damaging, epiphenomenal responses. The field of Primary Immunodeficiencies focuses on the characterization of humans with inborn errors of immunity. These rare conditions permit the identification of those molecular and cellular processes that are central to human susceptibility to microbes. In efforts to compensate for defective host responses, this field has also provided a wealth of clinical experience in the effective use of cytokines to treat various active infections, while demonstrating their safety. In this review, we provide a historical perspective of the treatment of infectious diseases, evolving from a focus on the microbe, to an understanding of human immunity; we then outline the growing contribution of Primary Immunodeficiencies to the rational use of adjunctive cytokine immunotherapy in the management of infections.

Interleukin 7 receptor alpha chain haplotypes vary in their influence on multiple sclerosis susceptibility and response to interferon Beta

Interleukin 7 receptor alpha chain (IL-7Ralpha) has recently been confirmed as the first non-HLA gene definitively associated with multiple sclerosis (MS). The protective haplotype (haplotype 2) has reduced splicing of exon 6, reduced production of soluble IL-7Ralpha, and therefore reduced interference with receptor binding to its ligands, IL-7, and thymic stromal lymphopoietin (TSLP). From a meta-analysis on 3,376 MS patients, 4,143 controls, and 1,333 trio families, although the most significant association is still seen with haplotype 2 (P = 7 x 10(-10)), the highest odds ratio is seen for haplotype 4 homozygotes (OR = 1.35, P = 0.001). The IL-7Ralpha proximal promoter contains response elements to interferon beta (IFN-beta), the most commonly used immunomodulatory drug in MS. We demonstrate that IL-7Ralpha is up-regulated in response to IFN-beta in vitro for haplotypes 1 and 2, but not 4. This difference can be seen in peripheral blood mononuclear cells (PBMC) from heterozygotes (P < 0.002, n = 10) and homozygotes (trend only), and in CD4 + CD45RO + and CD4 + CD45RA + cells. In PBMCs, IL-7Ralpha cell surface protein (CD127) is lower in haplotype 4 carriers than non-carriers after incubation with IFN-beta (P < 0.003, n = 20). Response to IFN-beta includes viral protection and immune modulation, processes that could be pathogenically significant in MS. The haplotype-dependent variation in the regulation of IL-7Ralpha by IFN-beta may contribute to the genetic association of IL-7Ralpha with MS.