Immune phenotyping in a pediatric multicenter transplant study: Suitability of a preformulated dry-antibody panel system.

Flow-cytometric immune phenotyping is influenced by cryopreservation and inter-laboratory variability limiting comparability in multicenter studies. We assessed a system of optimized, pre-mixed dry-antibody panel tubes requiring small amounts of whole blood for validity, reliability and challenges in a Canadian multicenter study (POSITIVE) with long-distance sample shipping, using standardized protocols. Thirty-seven children awaiting solid-organ transplant were enrolled for parallel immune-phenotyping with both validated, optimized in-house panels and the dry-antibody system. Samples were collected before, 3 and 12 months post-transplant. Quality-assurance measures and congruence of phenotypes were compared using Bland-Altman comparisons, linear regression and group comparisons. Samples showed excellent lymphocyte viability (mean 94.8 %) and recovery when processed within 30 h. Comparing staining methods, significant correlations (Spearman correlation coefficient >0.6, p < 0.05), mean difference <5 % and variation 2SD <25 % were found for natural-killer, T and B cells, including many immunologically important cell subsets (CD8+, naïve, memory CD4+ T; switched-memory, transitional B). Some subgroups (plasmablasts, CD1d+CD5hi B cells) showed weak correlations, limiting interpretation reliability. The dry-antibody system provides a reliable method for standardized analysis of many immune phenotypes after long-distance shipping when processed within 30 h, rendering the system attractive for pediatric studies due to small blood amounts required and highly standardized processing and analysis.

The IPTA Nashville consensus conference on post-transplant lymphoproliferative disorders after solid organ transplantation in children: IV-consensus guidelines for the management of post-transplant lymphoproliferative disorders in children and adolescents.

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders (PTLD) after pediatric solid organ transplantation. This report addresses the outcomes of deliberations by the PTLD Management Working Group. A strong recommendation was made for reduction in immunosuppression as the first step in management. Similarly, strong recommendations were made for the use of the anti-CD20 monoclonal antibody (rituximab) as was the case for chemotherapy in selected scenarios. In some scenarios, there is uncoupling of the strength of the recommendations from the available evidence in situations where such evidence is lacking but collective clinical experiences drive decision-making. Of note, there are no large, randomized phase III trials of any treatment for PTLD in the pediatric age group. Current gaps and future research priorities are highlighted.

Disproportionate Rates of COVID-19 Among Black Canadian Communities: Lessons from a Cross-Sectional Study in the First Year of the Pandemic.

BACKGROUND: Racialized communities, including Black Canadians, have disproportionately higher COVID-19 cases. We examined the extent to which SARS-CoV-2 infection has affected the Black Canadian community and the factors associated with the infection. METHODS: We conducted a cross-sectional survey in an area of Ontario (northwest Toronto/Peel Region) with a high proportion of Black residents along with 2 areas that have lower proportions of Black residents (Oakville and London, Ontario). SARS-CoV-2 IgG antibodies were determined using the EUROIMMUN assay. The study was conducted between August 15, 2020, and December 15, 2020. RESULTS: Among 387 evaluable subjects, the majority, 273 (70.5%), were enrolled from northwest Toronto and adjoining suburban areas of Peel, Ontario. The seropositivity values for Oakville and London were comparable (3.3% (2/60; 95% CI 0.4-11.5) and 3.9% (2/51; 95% CI 0.5-13.5), respectively). Relative to these areas, the seropositivity was higher for the northwest Toronto/Peel area at 12.1% (33/273), relative risk (RR) 3.35 (1.22-9.25). Persons 19 years of age or less had the highest seropositivity (10/50; 20.0%, 95% CI 10.3-33.7%), RR 2.27 (1.23-3.59). There was a trend for an interaction effect between race and location of residence as this relates to the relative risk of seropositivity. INTERPRETATION: During the early phases of the pandemic, the seropositivity within a COVID-19 high-prevalence zone was threefold greater than lower prevalence areas of Ontario. Black individuals were among those with the highest seroprevalence of SARS-CoV-2.

Serum immunoreactive erythropoietin levels and associated factors amongst HIV-infected children

OBJECTIVES: To determine the spectrum of serum immunoreactive erythropoietin (SIE) levels amongst HIV-infected children aged <13 years in relation to the levels among healthy children as well as those with renal failure; to examine the relationship between clinical and laboratory parameters and SIE levels. DESIGN: A cross-sectional study with a descriptive non-interventional format. HIV-infected Canadian subjects were recruited through four tertiary Canadian and one Bahamian centre. Children with renal failure and healthy children were recruited from one of the Canadian centres. METHODS: Study subjects had clinical and laboratory profiles determined at baseline and at each of five follow-up periods over 1 year. SIE levels were measured by radio-immunoassay with a normal range of 12-28 IU/I. Data handling and statistical functions were performed by the Canadian HIV Trials Network. RESULTS: Ths study enrolled 133 HIV-infected subjects and 38 controls. Of these, 117 HIV-infected subjects, 24 healthy controls, and 11 controls with renal failure were eligible for analysis. The median age of infected subjects was 44 months, whereas that of healthy controls was 56 months, and 95 months for controls with renal failure. The median SIE levels were 14 and 11 IU/I for subjects with renal failure and healthy subjects, respectively. The median SIE level was 61 IU/I among zidovudine (ZDV)-treated subjects and 22 IU/I among ZDV-naive HIV-infected subjects. HIV-infected children almost invariably had SIE levels < 200 IU/I. The median SIE levels amongst HIV-infected subjects whose hemoglobin levels were < 100 g/l were 98 and 31 IU/I for ZDV-treated and ZDV-naive subjects, respectively (P = 0.002). This difference in median SIE levels between ZDV-treated subjects and ZDV-naive subjects was also observed among subjects whose hemoglobin levels were > 100 g/l (median, 58 and 15 IU/I, respectively; P < 0.001). Hemoglobin level was the most important predictor of log10 SIE (P < 0.001 for ZDV-treated and ZDV-naive subjects). CONCLUSIONS: SIE levels amongst HIV-infected children were affected by HIV infection, use of ZDV, and presence or absence of anemia. SIE levels amongst HIV-infected children were generally lower than 200 IU/I. This characterization of SIE levels will facilitate clinical trials of exogenous recombinant human erythropoietin in HIV-infected children with anemia.(Au)

The growing problem of resistance to zidovudine (ZDV): a genotype analysis

The objectives of this cross-sectional survey were to determine the prevalence and clinical significance of mutations conferring ZDV genotypic resistance among HIV-1 strains from HIV infected Canadian children. We screened for mutations at reverse transcriptase (RT) codons 215 and 219 by direct sequencing of polymerase chain reaction (PCR) products amplified from HIV-1 proviral DNA. An automated AB1 373A sequencer and a Taq Dye Dideoxy cycle seqencing kit were used for gentopic testing. Among 51 ZDV-experienced children evaluated prior to December 31, 1995, the mean (ñSD) age was 84.8 (ñ59) months. The RT mutations at 215 and 219 were deduced in 25/51 (49 percent) of subjects. The mean duration of ZDV treatment among children with mutations was 23.4 months (SDñ16.6) compared with 9.9 (SDñ17.5) months for those without mutations (P = <.007). Children with mutations had lower baseline CD4 counts (means ñ SD, 359 ñ 542/mm versus 705 ñ 548/mm, P = .03). Similarly, there was significant difference in CD4 counts (means ñ SD, 225 ñ 439/mm versus 559 ñ 556/mm, respectively; P = .04). HIV-1 RT mutations at codons 215 and 219 were found in a significant number of children in our cohort and were associated with evidence of advanced disease. Periodical genotypic surveys will guide antiretroviral therapy in HIV infected children in setting similar to ours. However, given the potential for transmission of resistant strains globally, such surveys may be of value in selected populations to assess the potential of drug resistance prior to initiation of antiretroviral therapy.(AU)

Cross sectional study of zidovudine resistance among HIV-infected children - abstract

The objectives of this study were to define the extent ofzidovudine (ZDV) resistance and to determine the association between resistance and clinical, virologic and epidemiologic variables among HIV-infected children. Subjects were recruited from 7 Canadian centres. Epidemiologic, clinical and laboratory data were collected on all subjects. Mononuclear cells from heparinized anticoagulated blood from each subject were isolated by density gradient centrifugation and quantitative cultures established for the determination of viral titres. Quantitative cultures were also performed in the presence of 5 um of zidovudine for 14 days; a reduction in viral titre in the presence of the drug was taken as a marker of susceptibility. The study has enrolled 102 subjects. Preliminary data on the first 52 children show that 76 per cent had perinatallly-acquired infection, while tranfusions and sexual transmission accounted for 24 per cent. The country of maternal birth was Canada in 64 per cent. The mean age was 84 months (sd ñ 57) and the HIV disease stage was P2 in 85 per cent. The mean CD4 count was 464/mm3; mean duration of ZDV treatment 17.2 months. ZDV resistance was found in 25 per cent (13/52) while 13.5 per cent (7/52) had intermediate susceptibility. Among factors potentially associated with resistance, duration of ZDV therapy was significant (p = 0.03) We are currently examining the relationship between resistance and viral load and phenotype, respectively. These preliminary data document the growing problem of zidovudine resistance among HIV-infected children in Canada, with 1 child out of every 4 in our cohort having ZDV-resistant virus. This highlights the need for a careful review of current anti-retroviral treatment strategies for HIV-infected children (AU)

Important issues in the clinical management of HIV/AIDS in the Caribbean: adult and paediatric perspectives - abstract

The HIV pandemic continues to increase in virtually all regions. Prevention remains the most important and cost-effective means of controlling the pandemic. However, as individuals are surviving for longer periods than in the early stages of the pandemic, clinicians face specific new therapeutic challenges in caring for HIV-infected individuals. Among the various challenges are the emergence of AZT-resistant HIV among adults and children, the appropriate treatment strategies for the growing population of long-term survivors, as well as the unique aspects of paediatric AIDs. Treatment guidelines are often based on the clinical spectrum of problems faced in the developed countries. However, these approaches may not be applicable to developing countries, due in part to economic factors as well as to the different spectrum of microbial agents. This presentation reviews the current suggested approaches to the cost-effective treatment of HIV/AIDs in the Caribbean in the context of emerging data. Specific clinical scenarios are outlined to illustrate the treatment of important clinical problems. The unique aspects of paediatric HIV are outlined. The approach to treatment of perinatal cases (rapidly progressive HIV with encephalopathy versus slowly progressive disease) is discussed (AU)

Occupational percutaneous exposure to human immunodeficiency virus (HIV); a decision analysis from a Caribbean perspective - abstract

A decision analysis was conducted to examine whether short-term (42 days) zidovudine should be recommended for Caribbean health care workers (HCWs), following percutaneous exposure to blood, as well as to determine the value of testing "donor" (patient's) blood. The results were compared with a similar analysis based on a North American model. The options analyzed were "TREAT ALL", "TREAT NONE"; and "TEST". In the "TREAT ALL" option, all HWCs receive short-term zidovudine immediately after exposure, "TREAT NONE" option no one receives zidovudine and in the "TEST" option, "donor" blood is tested, and if HIV-positive, zidovudine is given. Each outcome was expressed as a utility; this is a method of quantifying the values that individuals place on health states. The results showed that the "TEST" option is preferred. The value of testing "donor" blood is derived from the fact that the vast majority of HCWs would be reassured by a negative test. Sensitivity analyses indicated that even if the risk of seroconversion or the effectiveness of zidovudine is zero, this option is preferred; thus confirming the above value of testing, rather than merely identifying HCWs who should receive zidovudine. If HIV-seropositivity exceeds 42 per cent, the "TREAT NONE" option is preferred. This was found to be due to the fact that increased numbers of HCWs would be told that they were exposed to HIV-positive blood. The "worrying factor" associated with such an exposure is such that above 42 per cent HIV seropositivity, the "TREAT NONE" option is preferred. In summary, the real value of testing "donor" blood is in identifying those persons who could be told that they were exposed to HIV-negative blood; that is reducing their "worry factor" to zero. If the risk of HIV-positivity exceeds 42 per cent, in particular groups of Caribbean patients, the "TREAT NONE" option is preferred. Because AIDS is a fatal disease, and given that zidovudine is the only available prophylactic agent at present, the drug has a role to play if its effectiveness is greater than zero. In this regard, the approach should be similar to that adopted for developed countries (AU)

An elective project on maternal mortality at U.H.W.I. - 1976-1980

Maternal deaths in th 1975-80 period, UHWI were analysed as an elective project. Most deaths were referred from other hospitals. Most deaths were preventable and the traditional triad of haemorrhage, infection and toxaemia were responsible for most deaths (AU)