Immunizations for the immunocompromised child

Assessment of microbiological correlates and immunostimulatory potential of electron beam inactivated metabolically active yet non culturable (MAyNC) Salmonella Typhimurium

This study investigates the microbiological and immunological basis underlying the efficacy of electron beam-inactivated immune modulators. The underlying hypothesis is that exposure to eBeam-based ionization reactions inactivate microorganisms without modifying their antigenic properties and thereby creating immune modulators. The immunological correlates of protection induced by such eBeam based Salmonella Typhimurium (EBST) immune modulators in dendritic cell (DC) (in vitro) and mice (in vivo) models were assessed. The EBST stimulated innate pro inflammatory response (TNFα) and maturation (MHC-II, CD40, CD80 and CD86) of DC. Immuno-stimulatory potential of EBST was on par with both a commercial Salmonella vaccine, and live Salmonella cells. The EBST cells did not multiply under permissive in vitro and in vivo conditions. However, EBST cells remained metabolically active. EBST immunized mice developed Salmonella-specific CD4+ T-cells that produced the Th1 cytokine IFNγ at a level similar to that induced by the live attenuated vaccine (AroA^- ST) formulation. The EBST retained stable immunogenic properties for several months at room temperature, 4°C, and -20°C as well as after lyophilization. Therefore, such eBeam-based immune modulators have potential as vaccine candidates since they offer the safety of a “killed” vaccine, while retaining the immunogenicity of an “attenuated” vaccine. The ability to store eBeam based immune modulators at room temperature without loss of potency is also noteworthy.

Immunologic effects of hydroxyurea in sickle cell anemia

BACKGROUND AND OBJECTIVE

Susceptibility to encapsulated bacteria is well known in sickle cell disease (SCD). Hydroxyurea use is common in adults and children with SCD, but little is known about hydroxyurea's effects on immune function in SCD. Because hydroxyurea inhibits ribonucleotide reductase, causing cell cycle arrest at the G1-S interface, we postulated that hydroxyurea might delay transition from naive to memory T cells, with inhibition of immunologic maturation and vaccine responses.

METHODS

T-cell subsets, naive and memory T cells, and antibody responses to pneumococcal and measles, mumps, and rubella vaccines were measured among participants in a multicenter, randomized, double-blind, placebo-controlled trial of hydroxyurea in infants and young children with SCD (BABY HUG).

RESULTS

Compared with placebo, hydroxyurea treatment resulted in significantly lower total lymphocyte, CD4, and memory T-cell counts; however, these numbers were still within the range of historical healthy controls. Antibody responses to pneumococcal vaccination were not affected, but a delay in achieving protective measles antibody levels occurred in the hydroxyurea group. Antibody levels to measles, mumps, and rubella showed no differences between groups at exit, indicating that effective immunization can be achieved despite hydroxyurea use.

CONCLUSIONS

Hydroxyurea does not appear to have significant deleterious effects on the immune function of infants and children with SCD. Additional assessments of lymphocyte parameters of hydroxyurea-treated children may be warranted. No changes in current immunization schedules are recommended; however, for endemic disease or epidemics, adherence to accelerated immunization schedules for the measles, mumps, and rubella vaccine should be reinforced.

Immunogenicity of hepatitis a vaccine in children with cancer

This study evaluated the immuned response of the hepatitis A vaccine in children with cancer who were receiving chemotherapy. Twenty-eight patients with lymphomas or solid tumors and who had negative serology for hepatitis A were enrolled. The median age was 4.7 years (range 2-16). The patients received 1440 IU hepatitis A vaccine at 0 and 6 months. Seroconversion rates at the first and seventh months were 60% (n = 17/28 patients) and 89% (n = 24/27 patients). No adverse effects were observed. The hepatitis A vaccine was found to be effective and safe in children with cancer.

Safety of live-virus vaccines for children with immune deficiency

PURPOSE

Conduct an integrative literature review to evaluate the safety and effectiveness of live-virus vaccines, namely, the measles, mumps, rubella, and varicella vaccines, in children who are immune compromised by exogenous medication either posttransplant or while undergoing maintenance chemotherapy for leukemia.

DATA SOURCES

Medline, MedlinePlus, EBSCO, PubMed, MD Consult, CINAHL, Clinical Pharmacology, ERIC, Biomedical Reference Collection-Basic, Health Source-Consumer Edition, Health Source-Nursing/Academic Edition, Ovid, CANCERLIT, and the Cochrane Library Online.

CONCLUSIONS

Because measles infection has a low incidence rate in the United States, it may be advisable not to vaccinate children who are immunocompromised and risk side effects of the vaccine. In contrast to measles infection, varicella has a higher incidence rate and poses a more imminent threat to those who are immunocompromised. Children who are immunosuppressed can receive the varicella vaccination; however, they should have regular titers drawn to confirm adequate protection against the disease and should receive boosters as deemed appropriate.

IMPLICATIONS FOR PRACTICE

The number of solid organ transplant recipients is steadily increasing with more than 600,000 solid organ transplantations worldwide since the first renal transplant in 1954. The steadily increasing numbers of pediatric patients surviving transplantation, coupled with increased life expectancy, accelerate the need for nurse practitioners to understand the management of these delicate patients following release from the transplant unit.

Pediatric Rheumatology for the Adult Rheumatologist I

Treatment of children with rheumatic diseases has advanced with novel therapeutics and the use of early aggressive treatment to achieve better long-term functional outcome. Many of the current treatments in pediatric rheumatology are based on studies in adults on medications without U.S. Food and Drug Administration labeling for pediatric use. This is not ideal because the pharmacokinetics (absorption, distribution, metabolism, and elimination) of many medications when used in children vary according to age, somatic growth, sexual maturity, and ontogeny of drug-metabolizing enzymes. Special dosing, administration considerations, and toxicity screening are reviewed for the more commonly used medications. Vaccinations for children on antirheumatic drugs are also discussed. Continued study of the long-term impact of medications and biologic treatments on children is necessary, but given the paucity of children with rheumatic diseases, this will require multicentered trials and collaborations. Lastly, this article reviews recent regulatory and legislative action on pediatric drug testing. Passage of the Pediatric Research Equity Act of 2003, which requires testing of pharmaceuticals in children, will facilitate more rational use of drugs in pediatric rheumatic diseases in the future.

Immunogenicity and tolerability of a trivalent virosomal influenza vaccine in a cohort of HIV-infected children

Twenty-three children infected with the human immunodeficiency virus (HIV) were vaccinated with a trivalent inactivated virosomal influenza vaccine. Serum haemagglutinin inhibition antibody titres were determined for the three viral strains at the time of vaccination and 1 month later. CD4 cell counts and HIV viral loads were measured to evaluate the effect of vaccination on HIV status. Adverse reactions were monitored during the first hour following vaccination by an investigator and then on a continuous basis by the parents. Seroconversion rates against the three viral strains A/H3N2, A/H1N1 and B were 73.9%, 56.5% and 52.2%, respectively. Geometric mean antibody titres increased after 1 month compared with baseline values (A/H3N2: 70.9 versus 13.5; A/H1N1: 24.7 versus 5.8; B: 34.4 versus 9.1). No significant changes were observed in either HIV viral load or CD4 cell count following vaccination. Vaccination was well tolerated with only a few mild, transient symptoms.

Improvements in immunization compliance using a computerized tracking system for inner city clinics

Vaccination compliance rates were calculated for 1995 to 2001 for enrolled patients, based on the Centers for Disease Control and Prevention guidelines and age-appropriate vaccine schedules. The results reported here indicate computerized tracking with the Doctor's Pediatric Immunization Program (Dr. PIP) maintained vaccine compliance rates (> 90%) in healthy and immunocompromised children at 2 months and 12 months of age. Instituting the computerized system has yielded nearly optimal results in both indigenous inner-city clinics. Despite the efficient progress made by automated tracking, the results for specific vaccine strategies (Varicella) and target groups (human immunodeficiency virus, high-risk indigent populations) may require on-going and intensive educational efforts to achieve optimization levels.

Safety, efficacy, and immunogenicity of a modified-live equine influenza virus vaccine in ponies after induction of exercise-induced immunosuppression

OBJECTIVE

To determine safety, efficacy, and immunogenicity of an intranasal cold-adapted modified-live equine influenza virus vaccine administered to ponies following induction of exercise-induced immunosuppression.

DESIGN

Prospective study.

ANIMALS

Fifteen 9- to 15-month old ponies that had not had influenza.

PROCEDURE

Five ponies were vaccinated after 5 days of strenuous exercise on a high-speed treadmill, 5 were vaccinated without undergoing exercise, and 5 were not vaccinated or exercised and served as controls. Three months later, all ponies were challenged by nebulization of homologous equine influenza virus. Clinical and hematologic responses and viral shedding were monitored, and serum and nasal secretions were collected for determination of influenza-virus-specific antibody isotype responses.

RESULTS

Exercise caused immunosuppression, as indicated by depression of lymphocyte proliferation in response to pokeweed mitogen. Vaccination did not result in adverse clinical effects, and none of the vaccinated ponies developed clinical signs of infection following challenge exposure. In contrast, challenge exposure caused marked clinical signs of respiratory tract disease in 4 control ponies. Vaccinated and control ponies shed virus after challenge exposure. Antibody responses to vaccination were restricted to serum IgGa and IgGb responses in both vaccination groups. After challenge exposure, ponies in all groups generated serum IgGa and IgGb and nasal IgA responses. Patterns of serum hemagglutination inhibition titers were similar to patterns of IgGa and IgGb responses.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that administration of this MLV vaccine to ponies with exercise-induced immunosuppression was safe and that administration of a single dose to ponies provided clinical protection 3 months later.