[HHV-8 Related immunological and hematological diseases]. / Maladies immunologiques et hématologiques liées à HHV-8.

HHV-8 is an oncogenic Gammaherpesvirinae discovered in 1994 during the HIV pandemic. It is the causative agent of Kaposi's sarcoma, and is also associated with the occurrence of several aggressive B lymphoproliferative disorders. Most of them occur in an immunosuppression setting, usually due to HIV infection. Multicentric HHV8-associated Castleman's disease and KSHV Inflammatory Cytokine Syndrome (KICS) are primarily reactive entities with prominent systemic features. They illustrate the cytokinic storm induced by HHV-8 in its cell host. On the other hand, HHV-8 can drive proliferation and lymphomagenesis of its plasmablastic cell host, and is associated with a risk to develop aggressive lymphomas with plasmacytic differenciation. Primary effusion lymphoma usually localizes in body cavities and may affect other extra-nodal sites ; its prognostic is poor. Diffuse large B-cell lymphoma HHV-8, NOS affect more commonly nodes and blood and evolve from infected cell of HHV-8 associated Castleman disease. On the contrary, germinotropic lymphoproliferative disorders presents mainly as localized adenopathy with indolent course, and show polyclonality. Histology plays a key role in distinguishing these different entities and need expert reviewing, especially since they may be associated with each other. Besides lymphoproliferative disorders, HHV8 is associated with various hematological manifestations. The aim of this review is to provide an update on the presentation, diagnosis, and management of immunologic and hematologic complications associated with HHV-8.

[EBV and immunodeficiency]. / EBV et immunodépression.

Epstein-Barr virus (EBV), discovered in 1964, is a double-stranded DNA virus belonging to the Herpesviridae family. EBV has a lymphoid tropism with transforming capacities using different oncogenic viral proteins. This virus has two replication cycles: a lytic cycle mainly occuring during primary infection and a latent cycle allowing viral persistence into host memory B cells. More than 90% of adults are seropositive for EBV worldwide, with a past history of asymptomatic or mild primary infection. EBV infection can sometimes cause life-threatening complications such as hemophagocytic lymphohistiocytosis, and lead to the development of lymphoproliferative disorders or cancers. Risk factors associated with these phenotypes have been recently described through the study of monogenic primary immune deficiencies with EBV susceptibility. We here review the virological and immunological aspects of EBV infection and EBV-related complications with an overview of current available treatments.

HIV Tat induces a prolonged MYC relocalization next to IGH in circulating B-cells.

With combined antiretroviral therapy (cART), the risk for HIV-infected individuals to develop a non-Hodgkin lymphoma is diminished. However, the incidence of Burkitt lymphoma (BL) remains strikingly elevated. Most BL present a t(8;14) chromosomal translocation which must take place at a time of spatial proximity between the translocation partners. The two partner genes, MYC and IGH, were found colocalized only very rarely in the nuclei of normal peripheral blood B-cells examined using 3D-FISH while circulating B-cells from HIV-infected individuals whose exhibited consistently elevated levels of MYC-IGH colocalization. In vitro, incubating normal B-cells from healthy donors with a transcriptionally active form of the HIV-encoded Tat protein rapidly activated transcription of the nuclease-encoding RAG1 gene. This created DNA damage, including in the MYC gene locus which then moved towards the center of the nucleus where it sustainably colocalized with IGH up to 10-fold more frequently than in controls. In vivo, this could be sufficient to account for the elevated risk of BL-specific chromosomal translocations which would occur following DNA double strand breaks triggered by AID in secondary lymph nodes at the final stage of immunoglobulin gene maturation. New therapeutic attitudes can be envisioned to prevent BL in this high risk group.

Efficiency of immunoglobulin G replacement therapy in common variable immunodeficiency: correlations with clinical phenotype and polymorphism of the neonatal Fc receptor.

Treatment of common variable immunodeficiency disorders (CVID) is based on replacement therapy using intravenous (i.v.) or subcutaneous (s.c.) immunoglobulin (Ig)G. Interindividual variation of IgG dose is common. A total of 380 CVID patients on stable IgG replacement from two prospective cohorts were analysed. An 'efficiency' index was defined as the ratio of serum IgG trough level minus IgG residual to the average weekly dose of IgG infusion. A reduced efficiency of IgG was associated independently with the i.v. route (P < 0·001) and with the presence of at least one CVID disease-related phenotype (lymphoproliferation, autoimmune cytopenia or enteropathy) (P < 0·001). High IgG efficiency was noted in patients homozygotes for the variable number tandem repeat (VNTR) 3/3 polymorphism of the neonatal Fc receptor gene [IgG Fc fragment receptor transporter alpha chain (FCGRT)] promoter, and this was particularly significant in patients treated with IVIG (P < 0.01). In a multivariate analysis, FCGRT VNTR 3/3 genotype (P = 0·008) and high serum albumin (P < 0·001) were associated independently with increased efficiency of i.v. Ig.

Human herpesvirus 8-related Castleman disease in the absence of HIV infection.

BACKGROUND: Castleman disease (CD) in the context of human immunodeficiency virus (HIV) infection is well described. It is almost always multicentric (MCD) and linked to human herpesvirus 8 (HHV-8). There are limited published data surrounding HHV-8-related CD among HIV-negative patients. METHODS: From January 1995 through June 2012, we identified in a single center 18 HIV-seronegative patients with HHV-8-related CD. We report on their clinical, pathological, and laboratory features. RESULTS: All cases were multicentric. Patients were aged 42-83 years and were referred with a relapsing remitting syndrome of fever (94%), constitutional symptoms (100%), peripheral lymphadenopathy (100%), splenomegaly (72%), hepatomegaly (50%), and edema (28%). Kaposi sarcoma was observed in 9 cases. Anemia and serum markers of inflammation were present in all cases. Polymerase chain reaction for HHV-8 DNA was positive on blood samples in all cases, whereas only 12 of 16 patients tested had positive HHV-8 serology at diagnosis. All cases showed the classic histological features of MCD, and LANA-1 immunostaining identified HHV-8-infected plasmablasts in 16 of 16 tested cases. Reactive hemophagocytic syndrome (44%), autoimmune hemolytic anemia (33%), and lymphoma (22%) were the commonest associated complications. Remission was obtained with etoposide in 13 of 15 cases. Rituximab allowed prolonged remission off therapy in 10 cases. Death occurred in 3 patients not treated with rituximab. These features were similar to those described in HIV-positive HHV-8-related MCD. Comparison between these 18 cases and 12 HIV-negative HHV-8-unrelated MCD cases showed marked discrepancies. CONCLUSIONS: HHV-8-associated MCD may be considered as a single clinicopathological entity regardless of HIV status.