Acute immune thrombocytopenic purpura in infants: associated factors, clinical features, treatment and long-term outcome

Immune thrombocytopenic purpura (ITP) associated with vaccinations: a review of reported cases

Immune thrombocytopenic purpura (ITP) is an autoimmune condition characterized by low platelet count with mucocutaneous and other bleedings. Clinical manifestations may range from spontaneous formation of purpura and petechiae, especially on the extremities, to epistaxis, bleeding at the gums or menorrhagia, any of which occur usually if the platelet count is below 20,000 per μl. A very low count may result in the spontaneous formation of hematomas in the mouth or on other mucous membranes. Fatal complications, including subarachnoid or intracerebral, lower gastrointestinal or other internal bleeding can arise due to an extremely low count. Vaccines may induce ITP by several mechanisms. Vaccine-associated autoimmunity may stem not only from the antigen-mediated responses but also from other constituents of the vaccine, such as yeast proteins, adjuvants, and preservatives diluents. The most likely is through virally induced molecular mimicry. The binding of pathogenic autoantibodies to platelet and megakaryocytes may cause thrombocytopenia by different mechanisms, such as opsonization, direct activation of complement, or apoptotic pathways. The autoantibodies hypothesis is not sufficient to explain all ITP cases: In the anti-platelet antibody-negative cases, a complementary mechanism based on T cell immune-mediated mechanism has been suggested. In particular, T cell subsets seem dysregulated with an increased production of pro-inflammatory cytokines, as IFN-γ and TNF, and chemokines, as CXCL10. Vaccines are one of the most striking discoveries in human history that changed dramatically life expectancy. Nonetheless, the occurrence of adverse events and autoimmune phenomena has been described following vaccination, and ITP may represent one of this.

Clinical features and major histocompatibility complex genes as potential susceptibility factors in pediatric immune thrombocytopenia

BACKGROUND/PURPOSE

Immune thrombocytopenia (ITP) is a heterogeneous autoimmune disorder with diverse response rates to treatments that include corticosteroids, intravenous immunoglobulins (IVIG), and splenectomy. The predisposing causes of this autoimmune disorder, one of which is immunogenetic susceptibility, have not been fully determined. We investigated whether clinical features and human leukocyte antigen (HLA) genotypes influence the occurrence, treatment response, and disease duration of childhood ITP in Taiwan.

METHODS

We performed HLA genotyping of 70 Taiwanese children with ITP and of 70 healthy controls and compared the data. Demographic data were also collected and evaluated.

RESULTS

The frequencies of heterozygous HLA-A11 and the HLA-Cw1 allele were both significantly decreased in the ITP group (p = 0.0160 and p = 0.0089, respectively), whereas the frequency of heterozygous HLA-DQ5 was significantly increased in the ITP group (p = 0.0057). Patients with HLA-DRB1*11 or -DRB1*15 were more likely to respond poorly to corticosteroids than IVIG (p = 0.0446 and p = 0.0008, respectively). In addition, we observed a positive association between HLA-A11 homozygosity and the development of persistent or chronic ITP [odds ratio (OR) = 6.3165, p = 0.0479]. The presence of HLA-DRB1*08 was, however, negatively correlated with the development of persistent or chronic ITP (OR = 0.1729, p = 0.0657). Children with antecedent of preceding illness (API) and with a younger age of onset were more likely to experience a better treatment response and shorter course of ITP.

CONCLUSION

We suggest that API, age of onset, and particular HLA class I and class II alleles, may be involved in and influence the occurrence and disease duration of childhood ITP, as well as responses to different therapeutic approaches.

Clinical features, prognostic factors, and their relationship with antiplatelet antibodies in children with immune thrombocytopenia

We investigated and evaluated the demographics, clinical and laboratory features, treatment responses, and disease duration of 25 children with immune thrombocytopenia (ITP) eligible for detection of antiplatelet antibodies. We found that patients without antecedent of preceding infection (API) were more likely to have anti-GPIa/IIa than those with API (42.9% vs. 5.5%, P=0.048). Age groups of <2 years and 2 to 10 years were more likely to show response (R) or complete response (CR) to given treatments, whereas none of the patients whose onset age >10 years showed R or CR to given treatments (88.9% and 100% vs 0%, P=0.001). The percentage of newly diagnosed ITP was higher in age groups of <2 years (100%) and in 2 to 10 years (90%) than the age group of >10 years (16.7%, P=0.001). Patients without API (71.4%) were more likely to develop chronic ITP than those with API (5.6%, P=0.002). In conclusion, younger age was a favorable prognostic factor, especially in patients <2 years of age with respect to treatment responses and disease duration. In addition, API was associated with a short disease course as well as absence of anti-GPIa/IIa.

Clinical features, treatment responses, and outcome of children with idiopathic thrombocytopenic purpura

The authors investigated demographics, clinical and laboratory features, treatment responses, and outcomes of 93 children (median age 5 years) admitted for idiopathic thrombocytopenic purpura (ITP). The therapy responses of high-dose methylprednisolone (HDMP) (n = 77) and intravenous immunoglobulin (IVIG) (n = 10) treatments were similar. None of the patients with hemorrhage died. Fifteen patients (16.1%) had progressed into chronic ITP. Seven infants had a probable relationship with vaccination; none of these infants progressed into chronic ITP. In conclusion, the overall prognosis in childhood ITP is good. The therapy responses of HDMP and IVIG treatments are similar. Also, ITP cases who havw vaccination history have a benign course.

Treatment of an infant with severe acute refractory immune thrombocytopenic purpura using combination therapy including rituximab

Some infants with acute immune thrombocytopenic purpura (ITP) do not respond to first-line therapy, and currently there is no consensus on therapy for these refractory cases. We describe a 12-week-old infant with acute ITP who was unresponsive to intravenous immunoglobulin and corticosteroid, and developed gastrointestinal bleeding. Several combination therapies were unsuccessful. After four doses of rituximab followed by intravenous immunoglobulin and corticosteroid, his platelet counts gradually increased. Combined therapy which includes rituximab may be a promising treatment for severe acute refractory ITP.

Immunogenicity, reactogenicity and consistency of production of a Brazilian combined vaccine against diphtheria, tetanus, pertussis and Haemophilus influenzae type b

A randomized, double-blinded study evaluating the immunogenicity, safety and consistency of production of a combined diphtheria-tetanus-pertussis-Haemophilus influenzae type b vaccine entirely produced in Brazil by Bio-Manguinhos and Instituto Butantan (DTP/Hib-BM) was undertaken. The reference vaccine had the same DTP vaccine but the Hib component was produced using purified materials supplied by GlaxoSmithKline (DTP/Hib-GSK), which is registered and has supplied the Brazilian National Immunization Program for over more than five years. One thousand infants were recruited for the study and received vaccinations at two, four and six months of age. With respect to immunogenicity, the vaccination protocol was followed in 95.6% and 98.4% of infants in the DTP/Hib-BM and DTP/Hib-GSK groups, respectively. For the Hib component of the study, there was 100% seroprotection (> or =0.15 microg/mL) with all three lots of DTP/Hib-BM and DTP/Hib-GSK. The geometric mean titer (GMT) was 9.3 microg/mL, 10.3 microg/mL and 10.3 microg/mL for lots 1, 2 and 3 of DTP/Hib-BM, respectively, and the GMT was 11.3 g/mL for DTP/Hib-GSK. For diphtheria, tetanus and pertussis, seroprotection was 99.7%, 100% and 99.9%, respectively, for DTP/Hib-BM, three lots altogether and 99.2%, 100% and 100% for DTP/Hib-GSK. GMTs were similar across all lots and vaccines. Adverse events rates were comparable among the vaccine groups. The Brazilian DTP/Hib vaccine demonstrated an immunogenicity and reactogenicity profile similar to that of the reference vaccine.

Comparison of idiopathic thrombocytopenic purpura in children between 3 months and 2 years versus 2-5 years

It has been reported that infantile idiopathic thrombocytopenic purpura (ITP) has different clinical features than ITP seen in older ages and classification of bleeding sites and grading of bleeding severity can be used in determining the risk of bleeding. In this study, patients with ITP were divided into two groups according to age (<2 years and 2-5 years). The clinical features, laboratory findings, treatment modalities, rate of response and chronicity, bleeding sites, grades of bleeding were compared between each group. No significant differences were established.