Acquired hypogammaglobulinemia and pathogen-specific antibody depletion after solid organ transplantation in human immunodeficiency virus infection: A brief report.

Hypogammaglobulinemia (HGG) frequently occurs in recipients after types of (SOT). The incidence and significance of HGG in HIV+ recipients of SOT are just being explored. We reported that 12% of the recipients in the SOT in multi-center HIV-TR (HIV-TR) Study developed moderate or severe HGG at 1 year. In LT recipients, this was associated with serious infections and death. We have now further characterized the decreased antibodies in HIV+ SOT recipients who developed HGG. We measured the levels of pathogen-specific antibodies and poly-specific self-reactive antibodies (PSA) in relation to total IgG levels from serial serum samples for 20 HIV+ SOT recipients who developed moderate to severe HGG following SOT. Serum antibody levels to measles, tetanus toxoid, and HIV-1 were determined by EIA. Levels of PSAs were determined by incubating control lymphocytes with patient serum, staining with anti-human IgG Fab-FITC, and analysis by flow cytometry. Levels of PSA were higher compared to healthy, HIV-uninfected controls at pre-transplant baseline and increased by weeks 12 and 26, but the changes were not significant. Likewise, anti-HIV antibody levels remained unchanged over time. In contrast, antibody levels against measles and tetanus were significantly reduced from baseline by week 12, and did not return to baseline, even after 2 years. For HIV patients who develop moderate to severe HGG after transplant, the reduction in IgG levels is associated with a significant decrease in pathogen-specific antibody titers, while PSA levels and anti-HIV antibodies are unchanged. This may contribute to infectious complications and other clinical endpoints.

Short communication: Apoptosis pathways in HIV-1-infected patients before and after highly active antiretroviral therapy: relevance to immune recovery.

Investigations into apoptotic pathways, intrinsic and extrinsic, and the effects of highly active antiretroviral therapy (HAART) on T cell death via those pathways may provide insight into the mechanisms of and barriers to immune recovery. HIV-1-infected patients were enrolled into a randomized, controlled study of the immune effects of a lopinavir/ritonavir (LPV/r)-based versus an efavirenz (EFV)-based HAART regimen in antiretroviral-naive subjects with CD4(+) counts <350 cells/mm(3). Patients were randomized to receive TDF/FTC/EFZ or TDF/FTC plus LPV/r. Fourteen patients were enrolled and 10 patients completed 6 months of therapy as per the protocol. CD4(+) counts were measured before and during HAART therapy. We isolated T cell subsets to measure ex vivo apoptosis by propidium iodide staining. We also assessed caspase activation for the intrinsic and extrinsic pathways of apoptosis, as well as effector caspase activation. We also measured mitochondrial membrane potential. Cells were analyzed by flow cytometry. All patients had increased activation of caspase 8 (extrinsic pathway), caspase 9 (intrinsic pathway), effector caspases 3/7, and low mitochondrial membrane potential at baseline compared to controls. By 4 weeks, there was a decrease in activation of all caspases, but little further decrease by week 24. T cell mitochondrial membrane potential did not increase until week 12, but continued to increase until week 24. The only predictor of CD4(+) count increase was the increase in mitochondrial membrane potential of naive cells at 6 months (r=0.66, p=0.038). This suggests that positive selection of naive CD4(+) T cells in the thymus is the major determinant of CD4(+) recovery.

Genetic analysis of influences on survival following Toxoplasma gondii infection.

Survival of mice during the acute stage of Toxoplasma gondii infection was not influenced by the MHC Class I gene, L(d), but was influenced by the MHC Class II genes, Ia and Ie. As unexplained variability was noted in our initial studies of influence of the L(d) gene on survival, influence of the L(d) gene region on survival in the presence of a number of variables was studied. Although route of administration and dose of parasites, and age and gender of the mice markedly influenced outcome of T. gondii infection, the Class I L(d) gene did not modify survival in any of these circumstances. In separate studies, using mice with a differing genetic background, i.e. H-2(b), C57BL/10 mice, presence of Ia or Ie alone diminished survival even though presence of Ia reduced parasite burden. When neither or both the Ia and Ie genes were present together, survival was greater. In separate analyses of our studies of AxB BxA recombinant inbred mice, similar influences of MHC genes on survival and parasite burden following peroral infection were confirmed. Previously undescribed associations of novel genetic loci and survival and parasite burden also were identified. Genetic loci associated with enhanced survival included D8Mit42, D1Mit3, Iapls1-16, D8Mit14, Hoxb, Mpmv29, Pmv45, and Emv-2; genetic loci associated with reduced parasite burden included H-2, D17Mit62, D17Mit83, D17Mit21, D17Mit34, D17Mit47, D18Mit4, and Gln3-5. These studies demonstrate the importance of MHC region genes (but not L(d)) for survival, and the influence of other novel genes, and endogenous and exogenous variables on survival and parasite burden specified by host genes following T. gondii infection.

Impact of visual impairment on measures of cognitive function for children with congenital toxoplasmosis: implications for compensatory intervention strategies.

OBJECTIVES: The purpose of this work was to determine whether visual impairment caused by toxoplasmic chorioretinitis is associated with impaired performance of specific tasks on standardized tests of cognitive function. If so, then we worked to determine whether there are patterns in these difficulties that provide a logical basis for development of measures of cognitive function independent of visual impairment and compensatory intervention strategies to facilitate learning for such children. METHODS: Sixty-four children with congenital toxoplasmosis with intelligence quotient scores > or = 50 and visual acuity sufficient to cooperate with all of the intelligence quotient subscales had assessments of their vision, appearance of their retinas, and cognitive testing performed between 3.5 and 5 years of age. These evaluations took place between 1981 and 1998 as part of a longitudinal study to determine outcome of congenital toxoplasmosis. Children were evaluated at 3.5 or 5 (37 children) or both 3.5 and 5 (27 children) years of age. Cognitive function was measured using the Wechsler Preschool and Primary Scale of Intelligence-Revised. Wechsler Preschool and Primary Scale of Intelligence-Revised scale scores were compared for children grouped as those children who had normal visual acuity in their best eye (group 1), and those who had impaired vision in their best eye (acuity < 20/40) because of macular disease (group 2). Demographic characteristics were compared for children in the 2 groups. Test scores were compared between groups using all of the 3.5-year-old visits, all of the 5-year-old visits, and using each child's "last" visit (ie, using the 5-year-old test results when a child was tested at both 3.5 and 5 years of age or only at 5 years, otherwise using the 3.5-year-old test results). The results were similar and, therefore, only the results from the last analysis are reported here. RESULTS: There were 48 children with normal visual acuity in their best eye (group 1) and 16 children with impaired vision because of macular involvement in their best eye (group 2). Ethnicity and socioeconomic scores were similar. There was a significantly greater proportion of males in group 2 compared with group 1 (81% vs 46%). There was no significant diminution in Wechsler Preschool and Primary Scale of Intelligence-Revised test scores between 3.5 and 5 years of age for the 27 children tested at both of these ages. Verbal intelligence quotient, performance intelligence quotient, full-scale intelligence quotient scores, and all of the scaled scores except arithmetic and block design were significantly lower for children in group 2 compared with group 1. The majority of the differences remained statistically significant or borderline significant after adjusting for gender. However, the difference in overall verbal scores does not remain statistically significant. Mean +/- SD verbal (98 +/- 20) and performance (95 +/- 17) intelligence quotients were not significantly different for children in group 1. However, verbal (88 +/- 13) and performance intelligence quotients (78 +/- 17) were significantly different for children in group 2. For children in group 2, their lowest scale scores were in object assembly, geometric design, mazes, and picture completion, all timed tests that involved visual discrimination of linear forms with small intersecting lines. In the 2 scales scored that did not differ between groups 1 and 2, arithmetic and block design, timing and vision but not linear forms were components of the tasks. Children with monocular and binocular normal visual acuity did not differ in verbal, performance, or full-scale intelligence quotients or any of the subscale tests. Difficulty with sight or concomitant neurologic involvement also seemed to impact the ability to acquire information, comprehension skills, and vocabulary and performance in similarities testing. After controlling for gender, however, these differences were diminished, and there were no longer differences in overall verbal scores. As noted above, results were generally similar when all of the tests for 3.5-year-olds or 5-year-olds were analyzed separately. At the 3.5-year visit there were fewer significant differences between the 2 groups for the verbal components than at the 5-year visit. CONCLUSIONS: In children with congenital toxoplasmosis and bilateral macular disease (group 2) because of toxoplasmic chorioretinitis, scaled scores were lowest on timed tests that require discrimination of fine intersecting lines. Although the severity of ocular and neurologic involvement is often congruent in children with congenital toxoplasmosis, ophthalmologic involvement seems to account for certain specific limitations on tests of cognitive function. Children with such visual impairment compensate with higher verbal skills, but their verbal scores are still less than those of children with normal vision, and in some cases significantly so, indicating that vision impairment might affect other aspects of cognitive testing. Patterns of difficulties noted in the subscales indicate that certain compensatory intervention strategies to facilitate learning and performance may be particularly helpful for children with these impairments. These patterns also provide a basis for the development of measures of cognitive function independent of visual impairment.

In vitro correlates of Ld-restricted resistance to toxoplasmic encephalitis and their critical dependence on parasite strain.

Resistance to murine toxoplasmic encephalitis has been precisely and definitively mapped to the L(d) class I gene. Consistent with this, CD8(+) T cells can adoptively transfer resistance to toxoplasmic encephalitis. However, cytotoxic CD8(+) T cells, capable of killing class I-matched, infected target cells, are generated during the course of Toxoplasma gondii infection even in mice lacking the L(d) gene. L(d)-restricted killing could not be demonstrated, and the functional correlate of the L(d) gene has therefore remained elusive. Herein, L(d)-restricted killing of T. gondii-infected target cells is demonstrated for the first time. L(d)-restricted killing is critically dependent on the strain of T. gondii and is observed with all the derivatives of type II strains tested, but not with a type I strain. These results have important implications for vaccine development.