Transient disappearance of immunologic disorders and remission after intercurrent measles infections in children with chronic idiopathic thrombocytopenic purpura

Viruses, anti-viral therapy, and viral vaccines in children with immune thrombocytopenia

Immune thrombocytopenia (ITP) might be preceded by silent or overt viral infections. Similarly, anti-viral drugs and viral vaccines could also trigger ITP and might play a central role in its pathogenesis. The seasonal nature of childhood ITP suggests that viral infections might initiate immune responses that increase the predisposition and occurrence of ITP. Active cytomegalovirus or Epstein-Barr virus should be considered in differential diagnosis when thrombocytopenia is associated with lymphadenopathy, especially with splenomegaly. This review will focus on the specific association of ITP in association with viral disease and vaccinations, and will discuss the effectiveness of current therapies in light of our current understanding of viral-associated ITP.

Bacterial Pneumonia-induced Persistent Remission of Severe Immune Thrombocytopenia after Allogeneic Hematopoietic Stem Cell Transplantation

A 53-year-old woman with chronic myeloid leukemia received allogeneic hematopoietic stem cell transplantation. After neutrophil engraftment, her platelet count exceeded 100,000/μL at day 64. While she was receiving corticosteroid treatment for chronic graft versus host disease (GVHD), her platelets suddenly dropped to 6,000/μL at day 210 and she was diagnosed with immune thrombocytopenia (ITP). Corticosteroids, intravenous high-dose gamma globulin (IVIg) and a splenectomy failed to increase her platelet count. She developed bacterial pneumonia at day 599 and antibiotic therapy was initiated. Soon after, her platelet count continuously increased. Her GVHD and ITP are now in remission without any ongoing treatment.

Measles immune suppression: lessons from the macaque model

Measles remains a significant childhood disease, and is associated with a transient immune suppression. Paradoxically, measles virus (MV) infection also induces robust MV-specific immune responses. Current hypotheses for the mechanism underlying measles immune suppression focus on functional impairment of lymphocytes or antigen-presenting cells, caused by infection with or exposure to MV. We have generated stable recombinant MVs that express enhanced green fluorescent protein, and remain virulent in non-human primates. By performing a comprehensive study of virological, immunological, hematological and histopathological observations made in animals euthanized at different time points after MV infection, we developed a model explaining measles immune suppression which fits with the "measles paradox". Here we show that MV preferentially infects CD45RA(-) memory T-lymphocytes and follicular B-lymphocytes, resulting in high infection levels in these populations. After the peak of viremia MV-infected lymphocytes were cleared within days, followed by immune activation and lymph node enlargement. During this period tuberculin-specific T-lymphocyte responses disappeared, whilst strong MV-specific T-lymphocyte responses emerged. Histopathological analysis of lymphoid tissues showed lymphocyte depletion in the B- and T-cell areas in the absence of apoptotic cells, paralleled by infiltration of T-lymphocytes into B-cell follicles and reappearance of proliferating cells. Our findings indicate an immune-mediated clearance of MV-infected CD45RA(-) memory T-lymphocytes and follicular B-lymphocytes, which causes temporary immunological amnesia. The rapid oligoclonal expansion of MV-specific lymphocytes and bystander cells masks this depletion, explaining the short duration of measles lymphopenia yet long duration of immune suppression.

Improvement of intractable childhood epilepsy following acute viral infection

In this study, we report 11 patients with intractable childhood epilepsy that improved following acute viral infection. The patients were 8 boys and 3 girls. Six of the 11 children were diagnosed as West syndrome (5 of the symptomatic type and 1 of the cryptogenic type). The remaining 5 children were myoclonic seizures. The patients became seizure free within 6 days following acute viral infections without an exchange or addition of antiepileptic drugs (AEDs). The types of acute viral infections were Exanthema subitum (Roseola infantum) in 5 patients, Rotavirus gastroenteritis in 2 patients, Measles infection in 2 patients, Herpetic stomatitis in 1 patient and Common cold in the remaining patient. Salaam seizures and/or tonic spasms disappeared within 6 days after the onset of viral infections, and hypsarrhythmia evolved to localized spikes on electroencephalography (EEG) in the patients with West syndrome. Epileptic seizures disappeared rapidly and EEG gradually normalized or improved in patients with myoclonic seizures. Four patients became seizure free for 5 years to 20 years. In 6 patients, seizures relapsed within 14 days to 1 month after the disappearance of seizures. One child remained seizure free for 12 months after viral infection. Common factors in 4 children who were continuously seizure free include (1) normal or almost normal findings of brain CT/MRI, (2) normal development prior to the onset of epileptic seizures, and (3) a short time interval between the onset of seizures and the acute viral infection. We propose several hypotheses including an immunological effect for the improvement of intractable childhood epilepsy following acute viral infection. Further study may provide important information concerning the mechanism of seizure control and the applicable to treatment for intractable childhood epilepsy.

Emerging diseases: Measles

High vaccination coverage rates and the administration of a second dose of measles vaccine have resulted in a significant decline in the incidence of measles and neurologic diseases due to measles in many countries. However, intermittent outbreaks of measles still occur even in countries with excellent vaccination coverage, suggesting the existence of high rates of measles virus introduction from endemic regions and/or waning of vaccine-induced immunity. Strategies to sustain high levels of global immunity to measles virus by increasing vaccine coverage with routine and supplementary vaccination campaigns must be supported.

Peripheral blood lymphopenia and neutrophilia in children with severe respiratory syncytial virus disease

It is not known why respiratory syncytial virus (RSV) is associated with prolonged sequelae in many children. Measles virus (also a paramyxovirus), acute stress in sepsis, and cardiac bypass all cause lymphopenia. Using a retrospective analysis of records of children in Bristol with RSV infections over 5 years, we found that children with RSV had lower lymphocyte counts than unstressed, stable children prior to cardiac surgery. Children who required intensive care had the lowest lymphocyte counts. Neutrophil counts were raised in RSV-infected children. These data may offer an insight into pathological mechanisms, and suggest new research avenues.

Cytokine production in vitro and the lymphoproliferative defect of natural measles virus infection

In natural measles virus infection, evidence of intense immune system activation is present simultaneously with clinically relevant immune suppression. While evidence of activation is most prominent early in the disease, skin test responses and in vitro lymphoproliferation are depressed for weeks after the onset of the rash. It is not known whether the prolonged period of reduced immune responsiveness results from a single defect or a succession of different abnormalities. To gain further insight into measles-induced immune suppression we studied the production of soluble IL-2 receptor (sIL-2R), interferon-gamma (IFN-gamma), IL-1 beta, and tumor necrosis factor (TNF alpha) by peripheral blood mononuclear cells (PBMC) isolated from measles patients at various times after the onset of the rash. Studies included addition of supplemental recombinant IL-1 beta (rIL-1 beta) or recombinant IL-2 (rIL-2) or suppression of prostaglandin synthesis by indomethacin (IM). Proliferation in response to phytohemagglutin (PHA) was abnormal at all stages of disease. During the acute phase (first week after the onset of the rash) spontaneous production of sIL-2R was increased (76 +/- 54 vs. controls 4 +/- 4; P less than 0.03), suggesting in vivo T cell activation while PHA-induced sIL-2R was decreased (228 +/- 43 vs. control 582 +/- 127; P less than 0.002), suggesting that the capacity to produce IL-2 in response to mitogen was limited. Supplementation of PHA-stimulated cultures with rIL-2 improved but did not normalize both proliferation (58,600 +/- 4900 to 70,700 +/- 4400 vs. control 97,700 +/- 15,500; P less than 0.03) and sIL-2R levels (114 +/- 58 to 309 +/- 87 vs. control 582 +/- 127; P less than 0.003). Both spontaneous (25 +/- 18 vs. control 237 +/- 92; P less than 0.002) and PHA-induced (20 +/- 20 vs. control 604 +/- 129; P less than 0.004) TNF alpha levels were subnormal and were not improved with rIL-2, rIL-1 beta, or IM, suggesting a block in monocyte TNF alpha production. Spontaneous and PHA-induced IFN-gamma and IL-1 beta levels were normal. During the convalescent phase (greater than 2 weeks after the onset of the rash), spontaneous levels of sIL-2R were normal and PHA-induced levels were completely normalized with supplemental rIL-2 but proliferation remained below normal.(ABSTRACT TRUNCATED AT 400 WORDS)

The changes of interleukin-2, tumour necrotic factor and gamma-interferon production among patients with Kawasaki disease

Included in this study were 43 cases of mucocutaneous lymph node syndrome (MCLS or Kawasaki disease) treated solely with aspirin. Of these, 19 developed coronary aneurysm. Mononuclear cells (MNC) of these MCLS patients were collected weekly and stimulated either with phytohaemagglutinin (PHA) or PHA plus phorbol myristic acetate. The production of interleukin-2 (IL-2), tumour necrotic factor (TNF) and gamma-interferon (IFN-r) was determined. In addition, IL-2, TNF, IFN-r from serial collections of serum samples of these patients were also measured. The results show that serum IL-2 and TNF were detected in the 1st week, reached maximal plateau in the 2nd and 3rd week and decreased 1 month later. The production of IL-2, TNF and IFN-r from MCLS patients' MNC increased from the 1st to the 3rd week, persisted at a high level for 1 month and then decreased. During the 2nd and 3rd weeks, there were significantly higher serum IL-2 levels and IL-2 production in patients with than in patients without coronary lesions. These observations suggest that the serum IL-2 level and IL-2 production during the 2nd week may serve as a predictive parameter for coronary aneurysm formation. It also suggests that the production of TNF, IL-2 and IFN-r from MNC may contribute to the development of vascular injury in acute MCLS.