Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 36-1993. A 28-year-old man with AIDS, persistent pancytopenia, and lymphoma

A Persistent Parvovirus Infection Causing Anemia in an HIV Patient Requiring Intravenous Immunoglobulin Maintenance Therapy

Anemia is a common finding in a human immunodeficiency virus (HIV)-positive patient with a wide range of possible causes and is a significant risk factor for mortality in acquired immunodeficiency syndrome (AIDS). Opportunistic parvovirus infection-causing pure red cell aplasia is one of its uncommon causes. It has been suggested that immunocompromised patients with abnormal antibody production are more susceptible to acquiring a chronic parvovirus infection requiring long-term intravenous immunoglobulin (IVIg) treatment; however, there are no specific guidelines for it. Here, we present a case of an HIV patient with persistent parvovirus infection resulting in chronic anemia requiring long-term maintenance immunoglobulin therapy with an excellent therapeutic response.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Modulation of inflammasome-mediated pulmonary immune activation by type I IFNs protects bone marrow homeostasis during systemic responses to Pneumocystis lung infection

Although acquired bone marrow failure (BMF) is considered a T cell-mediated autoimmune disease, possible innate immune defects as a cause for systemic immune deviations in response to otherwise innocuous infections have not been extensively explored. In this regard, we recently demonstrated an important role of type I IFNs in protecting hematopoiesis during systemic stress responses to the opportunistic fungal pathogen Pneumocystis in lymphocyte-deficient mice. Mice deficient in both lymphocytes and type I IFN receptor (IFrag(-/-) mice) develop rapidly progressing BMF due to accelerated bone marrow (BM) cell apoptosis associated with innate immune deviations in the BM in response to Pneumocystis lung infection. However, the communication pathway between lung and BM eliciting the induction of BMF in response to this strictly pulmonary infection has been unclear. In this study, we report that absence of an intact type I IFN system during Pneumocystis lung infection not only causes BMF in lymphocyte-deficient mice but also transient BM stress in lymphocyte-competent mice. This is associated with an exuberant systemic IFN-γ response. IFN-γ neutralization prevented Pneumocystis lung infection-induced BM depression in type I IFN receptor-deficient mice and prolonged neutrophil survival time in BM from IFrag(-/-) mice. IL-1β and upstream regulators of IFN-γ, IL-12, and IL-18 were also upregulated in lung and serum of IFrag(-/-) mice. In conjunction, there was exuberant inflammasome-mediated caspase-1 activation in pulmonary innate immune cells required for processing of IL-18 and IL-1β. Thus, absence of type I IFN signaling during Pneumocystis lung infection may result in deregulation of inflammasome-mediated pulmonary immune activation, causing systemic immune deviations triggering BMF in this model.

Management of persistent B19 parvovirus infection in AIDS

An HIV+ 26-year-old white man with a CD4 count of 0.06 x 10(9)/l was found to have red blood cell aplasia secondary to B19 parvovirus infection. Regular infusions of intravenous immunoglobulin (IVIG) were begun and resulted in marked reticulocytosis and correction of anaemia. The patient has been followed for over 4 years and has become anaemic and reticulocytopenic whenever IVIG was interrupted. Serial dot blot analysis of the patient's sera for B19 parvovirus DNA showed absence of DNA immediately following IVIG treatments but reappearance within 3-6 weeks. Regular IVIG was effective in controlling but not eradicating B19 parvovirus infection in this HIV+ patient.

AIDS, alcohol, endothelium, and immunity

Analogies are drawn between important unknowns in AIDS and alcohol research, related to underlying common pathogenetic mechanisms, immunodysregulation, cofactors, and prominent vascular manifestations. The central role of the blood and lymphatic vasculatures and specifically their endothelial lining in many facets of the immune response is reviewed. Evidence is presented that both alcohol and HIV (as well as other coinfecting viruses in AIDS) target and alter endothelial cells and the angiogenic process. These concepts are further illustrated by a serendipitous viral epidemic among rats on continuous long-term alcoholic and control nonalcoholic diets, where synergism between alcohol and virus appeared to underlie multiple vascular proliferative lesions in the liver. In AIDS and alcoholism/alcoholic liver disease (ALD), the prominent features of dysregulated angiogenesis point to the endothelium as a key player in pathogenesis of these seemingly disparate disorders and potentially in immunomodulation.