Adam J. Kanack

New low-frequency platelet glycoprotein polymorphisms associated with neonatal alloimmune thrombocytopenia

BACKGROUND: Recent reports suggest that maternal immunization against low‐frequency, platelet (PLT)‐specific glycoprotein (GP) polymorphisms is a more common cause of neonatal alloimmune thrombocytopenia (NATP) than previously thought.

New platelet glycoprotein polymorphisms causing maternal immunization and neonatal alloimmune thrombocytopenia.

BACKGROUND: Maternal immunization against low‐frequency, platelet (PLT)‐specific antigens is being recognized with increasing frequency as a cause of neonatal alloimmune thrombocytopenia (NAIT).

Prevalence and clinical significance of low‐avidity HPA‐1a antibodies in women exposed to HPA‐1a during pregnancy

BACKGROUND: Recent studies suggest that HPA‐1a–specific, low‐avidity maternal antibodies not detectable by conventional methods can cause neonatal alloimmune thrombocytopenia (NAIT). We performed studies to further define the incidence and clinical significance of this type of antibody.

Full-length recombinant choline transporter–like protein 2 containing arginine 154 reconstitutes the epitope recognized by HNA-3a antibodies

BACKGROUND: Recent reports have shown that the HNA‐3a leukocyte antigen, a target for antibodies that cause severe transfusion‐related acute lung injury, correlates with an arginine 154 (rather than glutamine) polymorphism in choline transporter–like protein 2 (CTL2) but did not show directly that R154 determines HNA‐3a. CTL2 peptides containing R154 are recognized by only half of HNA‐3a antibodies studied to date. Constructs that react with all HNA‐3a antibodies are needed to fully define the HNA‐3a epitope.

Primary Macrophages Rely on Histone Deacetylase 1 and 2 Expression To Induce Type I Interferon in Response to Gammaherpesvirus Infection

ABSTRACT Type I interferon is induced shortly following viral infection and represents a first line of host defense against a majority of viral pathogens. Not surprisingly, both replication and latency of gammaherpesviruses, ubiquitous cancer-associated pathogens, are attenuated by type I interferon, although the mechanism of attenuation remains poorly characterized. Gammaherpesviruses also target histone deacetylases (HDACs), a family of pleiotropic enzymes that modify gene expression and several cell signaling pathways. Specifically, we have previously shown that a conserved gammaherpesvirus protein kinase interacts with HDAC1 and -2 to promote gammaherpesvirus replication in primary macrophages. In the current study, we have used genetic approaches to show that expression of HDAC1 and -2 is critical for induction of a type I interferon response following gammaherpesvirus infection of primary macrophages. Specifically, expression of HDAC1 and -2 was required for phosphorylation of interferon regulatory factor 3 (IRF3) and accumulation of IRF3 at the beta interferon promoter in gammaherpesvirus-infected primary macrophages. To our knowledge, this is the first demonstration of a specific role for HDAC1 and -2 in the induction of type I interferon responses in primary immune cells following virus infection. Furthermore, because HDAC1 and -2 are overexpressed in several types of cancer, our findings illuminate potential side effects of HDAC1- and -2-specific inhibitors that are currently under development as cancer therapy agents. IMPORTANCE Gammaherpesviruses establish chronic infection in a majority of the adult population and are associated with several malignancies. Infected cells counteract gammaherpesvirus infection via innate immune signaling mediated primarily through type I interferon. The induction of type I interferon expression proceeds through several stages using molecular mechanisms that are still incompletely characterized. In this study, we show that expression of HDAC1 and -2 by macrophages is required to mount a type I interferon response to incoming gammaherpesvirus. The involvement of HDAC1 and -2 in the type I interferon response highlights the pleiotropic roles of these enzymes in cellular signaling. Interestingly, HDAC1 and -2 are deregulated in cancer and are attractive targets of new cancer therapies. Due to the ubiquitous and chronic nature of gammaherpesvirus infection, the role of HDAC1 and -2 in the induction of type I interferon responses should be considered during the clinical development of HDAC1- and -2-specific inhibitors.

USP5 Is Dispensable for Monoubiquitin Maintenance in Drosophila.

Ubiquitination is a post-translational modification that regulates most cellular pathways and processes, including degradation of proteins by the proteasome. Substrate ubiquitination is controlled at various stages, including through its reversal by deubiquitinases (DUBs). A critical outcome of this process is the recycling of monoubiquitin. One DUB whose function has been proposed to include monoubiquitin recycling is USP5. Here, we investigated whether Drosophila USP5 is important for maintaining monoubiquitin in vivo. We found that the fruit fly orthologue of USP5 has catalytic preferences similar to its human counterpart and that this DUB is necessary during fly development. Our biochemical and genetic experiments indicate that reduction of USP5 does not lead to monoubiquitin depletion in developing flies. Also, introduction of exogenous ubiquitin does not suppress developmental lethality caused by loss of endogenous USP5. Our work indicates that a primary physiological role of USP5 is not to recycle monoubiquitin for reutilization, but that it may involve disassembly of conjugated ubiquitin to maintain proteasome function.

Transfusion-related acute lung injury–associated HNA-3a antibodies recognize complex determinants on choline transporter-like protein 2

HNA‐3a–specific antibodies can cause severe, sometimes fatal, transfusion‐related acute lung injury when present in transfused blood. The HNA3‐a/b antigens are determined by an R154Q polymorphism in the first of five extracellular (EC) loops of the 10‐membrane‐spanning choline transporter‐like protein 2 (CTL2) expressed on neutrophils, lymphocytes, and other tissues. Approximately 50% of HNA‐3a antibodies (Type 1) can be detected using CTL2 Loop 1 peptides containing R154; the remaining 50% (Type 2) fail to recognize this target. Understanding the basis for this difference could guide efforts to develop practical assays to screen blood donors for HNA‐3 antibodies.

TRALI ASSOCIATED HNA-3a ANTIBODIES RECOGNIZE COMPLEX DETERMINANTS ON CHOLINE TRANSPORTER-LIKE PROTEIN 2 (CTL2)

HNA‐3a–specific antibodies can cause severe, sometimes fatal, transfusion‐related acute lung injury when present in transfused blood. The HNA3‐a/b antigens are determined by an R154Q polymorphism in the first of five extracellular (EC) loops of the 10‐membrane‐spanning choline transporter‐like protein 2 (CTL2) expressed on neutrophils, lymphocytes, and other tissues. Approximately 50% of HNA‐3a antibodies (Type 1) can be detected using CTL2 Loop 1 peptides containing R154; the remaining 50% (Type 2) fail to recognize this target. Understanding the basis for this difference could guide efforts to develop practical assays to screen blood donors for HNA‐3 antibodies.

Transfusion-related acute lung injury-associated HNA-3a antibodies recognize complex determinants on choline transporter-like protein 2: HNA-3a Antibody Recognition

HNA‐3a–specific antibodies can cause severe, sometimes fatal, transfusion‐related acute lung injury when present in transfused blood. The HNA3‐a/b antigens are determined by an R154Q polymorphism in the first of five extracellular (EC) loops of the 10‐membrane‐spanning choline transporter‐like protein 2 (CTL2) expressed on neutrophils, lymphocytes, and other tissues. Approximately 50% of HNA‐3a antibodies (Type 1) can be detected using CTL2 Loop 1 peptides containing R154; the remaining 50% (Type 2) fail to recognize this target. Understanding the basis for this difference could guide efforts to develop practical assays to screen blood donors for HNA‐3 antibodies.