Low penetrance, broad resistance, and favorable outcome of interleukin 12 receptor beta1 deficiency: medical and immunological implications.

The clinical phenotype of interleukin 12 receptor beta1 chain (IL-12Rbeta1) deficiency and the function of human IL-12 in host defense remain largely unknown, due to the small number of patients reported. We now report 41 patients with complete IL-12Rbeta1 deficiency from 17 countries. The only opportunistic infections observed, in 34 patients, were of childhood onset and caused by weakly virulent Salmonella or Mycobacteria (Bacille Calmette-Guérin -BCG- and environmental Mycobacteria). Three patients had clinical tuberculosis, one of whom also had salmonellosis. Unlike salmonellosis, mycobacterial infections did not recur. BCG inoculation and BCG disease were both effective against subsequent environmental mycobacteriosis, but not against salmonellosis. Excluding the probands, seven of the 12 affected siblings have remained free of case-definition opportunistic infection. Finally, only five deaths occurred in childhood, and the remaining 36 patients are alive and well. Thus, a diagnosis of IL-12Rbeta1 deficiency should be considered in children with opportunistic mycobacteriosis or salmonellosis; healthy siblings of probands and selected cases of tuberculosis should also be investigated. The overall prognosis is good due to broad resistance to infection and the low penetrance and favorable outcome of infections. Unexpectedly, human IL-12 is redundant in protective immunity against most microorganisms other than Mycobacteria and Salmonella. Moreover, IL-12 is redundant for primary immunity to Mycobacteria and Salmonella in many individuals and for secondary immunity to Mycobacteria but not to Salmonella in most.

A role for genetics in the immune response to the varicella vaccine.

BACKGROUND: A wide range in antibody titers has been found after immunization with the varicella vaccine, although the basis for these differences has not been described. METHODS: To evaluate the contribution of a genetic component in the immune response to the varicella vaccine, concordance for six-week postimmunization antibody titers was evaluated among 248 biologic siblings who participated in varicella vaccine clinical trials by comparing all pairs of siblings (151 pairs) to all possible unrelated, nonsibling pairs created from within this same cohort (30,477 pairs). RESULTS: Postimmunization antibody titers after 1 varicella vaccine dose were within the range observed historically among healthy vaccinees, with 85.4% of subjects having antibody responses greater than the approximate correlate of protection of 5 gpELISA units. Postimmunization antibody titers within sibling pairs clustered together more than or less than 10 gpELISA units when compared with within nonsibling pairs (P < 0.0001). Postimmunization titers within sibling pairs were also quantitatively closer together than were those within unrelated, nonsibling pairs (P = 0.022). The age-adjusted intraclass correlation coefficient indicated that the heritability of the varicella vaccine immune response is 45% (95% confidence interval of 15-75%). CONCLUSIONS: Similarities in siblings' response to varicella vaccine are supportive of the hypothesis that genetic factors play a role in the antibody response to the varicella vaccine.

Herpesviridae infections in newborns: varicella zoster virus, herpes simplex virus, and cytomegalovirus.

Varicella zoster virus (VZV), herpes simplex virus (HSV) and cytomegalovirus (CMV) are all members of the Herpesviridae family.Humans are the only source of infection for these double stranded DNA viruses. Infants may acquire these infections in utero, peripartum, or postnatally, resulting in a variety of clinical syndromes, ranging from asymptomatic infection to severe infection,with high mortality rates and significant long-term morbidity. This article presents the epidemiology, clinical characteristics, treatment,and prevention strategies for VZV, HSV, and CMV infections in infants.

Antiviral therapy in children with varicella zoster virus and herpes simplex virus infections.

A small number of antiviral drugs are available for the treatment of varicella zoster virus (VZV) and herpes simplex virus (HSV) infections in children. This review presents pharmacokinetic data on the following selected antiviral agents: aciclovir, valaciclovir, famciclovir, cidofovir and foscarnet. Support and current recommendations for the treatment of selected VZV and HSV infections in children will also be reviewed.

Neonatal herpes infection: diagnosis, treatment and prevention.

Approximately 2000 neonates contract infection due to herpes simplex virus each year in the United States. Although herpes simplex virus type 2 is responsible for most neonatal infections, approximately 30% of infections are caused by herpes simplex virus type 1. Infections are categorized by extent of disease into skin/eye/mouth, central nervous system and disseminated disease categories. Each disease category is responsible for roughly one third of neonatal infections. Mortality is highest in disseminated disease. Morbidity is highest for survivors of central nervous system infection. Treatment with high dose parenteral acyclovir (60 mg/kg/day) for 14-21 days improves outcome. Since most neonatal infections are acquired from contact with infected maternal genital tract secretions, potential preventative strategies include: Caesarean delivery, serologic screening of pregnant women, prophylactic acyclovir and vaccination. The two strategies currently accepted by most obstetricians are Caesarean delivery for women with active lesions or prodromal symptoms and prophylactic acyclovir for women with gestational herpes.

Impaired accumulation and function of memory CD4 T cells in human IL-12 receptor beta 1 deficiency.

Defects in IL-12 production or IL-12 responsiveness result in a vulnerability to infection with non-viral intracellular organisms, but the immunological mechanisms responsible for this susceptibility remain poorly understood. We present an immunological analysis of a patient with disseminated Salmonella enteritidis and a homozygous splice acceptor mutation in the IL-12Rbeta1-chain gene. This mutation resulted in the absence of IL-12Rbeta1 protein on PBMC and an inability of T cells to specifically bind IL-12 or produce IFN-gamma in response to either IL-12 or IL-23. The accumulation of memory (CD45R0(high)) CD4 T cells that were CCR7(high) (putative central memory cells) was normal or increased for age. Central memory CD4 T cells of the patient and age-matched controls were similar in having a low to undetectable capacity to produce IFN-gamma after polyclonal stimulation. In contrast, the patient had a substantial decrease in the number of CCR7(neg/dull) CD45R0(high) memory CD4 T cells (putative effector memory cells), and these differed from control cells in having a minimal ability to produce IFN-gamma after polyclonal stimulation. Importantly, tetanus toxoid-specific IFN-gamma production by PBMC from the patient was also significantly reduced compared with that in age-matched controls, indicating that signaling via the IL-12Rbeta1-chain is generally necessary for the in vivo accumulation of human memory CD4 T cells with Th1 function. These results are also consistent with a model in which the IL-12Rbeta1 subunit is necessary for the conversion of central memory CD4 T cells into effector memory cells.