External quality assessment for CD4 + T-lymphocyte count test: Performance of the Brazilian public health laboratories network.

The National Network for CD4+ T-lymphocyte counting of Brazil comprises 93 laboratories. This study reports the laboratory performances achieved in external quality assessment (EQA) rounds provides by Ministry of Health to evaluate the quality of the kits used and the performance of test by the technicians.Ten EQA rounds were analyzed according the EQA criteria aimed to evaluate individual laboratory performance on the basis of the accuracy of their results compared to the general mean obtained by all participating laboratories and the reproducibility of the results obtained between 2 samples from the same donor.The percentage of approved and failed laboratories in the EQAs tends to follow a uniform pattern. Since 2011, approval has remained above 80% and the failure rate has never exceeded 15%.EQA is very important to evaluate the performance of the laboratories, to identify monitor, and to resolve errors as quickly as possible.

Estimating Normal Values of Rare T-Lymphocyte Populations in Peripheral Blood of Healthy Cuban Adults.

INTRODUCTION Flow cytometry allows immunophenotypic characterization of important lymphocyte subpopulations for diagnosis of diseases such as cancer, autoimmune diseases, immunodeficiencies and some infections. Normal values of rare lymphoid cells in blood, quantified by cytometry, vary among different populations; so it is indispensable to obtain normal national values that can be used in clinical practice. OBJECTIVE Characterize distribution of rare T-lymphocyte populations in peripheral blood, specifically double-positive T, natural killer T and activated T lymphocytes, as well as their relationship to sex and age. METHODS A cross-sectional study was carried out in 129 adults (68 women, 61 men) aged >18 years, without chronic diseases or unhealthy habits, who signed informed consent. Peripheral blood was collected for immunophenotyping of lymphocyte subpopulations with monoclonal antibodies specific for CD4+CD8+ double-positive T cells, CD3+CD56+ natural killer T cells, and CD3+CD25+HLA-DR+ activated T cells. An eight-color flow cytometer (Beckman Coulter Gallios) was used. The analytic strategy was modified, associating variables of interest in a single graphic, using conventional monoclonal labeling antibodies. Medians and minimum and maximum percentiles (2.5 and 97.5, respectively) were used as descriptive statistics, stratified by sex, for cell counts and percentages. A linear regression model was applied to assess age effects and a two-tailed Mann-Whitney U test for independent samples was used to assess sex differences. The significance threshold was set as p ≤0.05. RESULTS Median percentages of total lymphocytes: natural killer T cells 6.3% (1.4%-23%) in men and 4.7% (0.8%-11.3%) in women (p = 0.003); activated T cells 1.0% (0.2%-2.2%) in men and 1.2% (0.4%-3.1%) in women, without statistical significance; and double positives 0.8% (0.1%-4.2%) in men and 0.9% (0.3-5.1) in women, also without statistical significance. Median cell counts (cells/mL) were: natural killer T cells, 126 (27-580) in men and 105 (20-279) in women (p = 0.023); activated T cells: 20 (4-46) in men and 25 (7-75) in women, (p = 0.013) and double-positive T cells: 17 (2-85) in men and 21 (7-154) in women, without statistical significance. Sex influenced natural killer T cells, but age did not. CONCLUSIONS Age does not affect counts and percentages of rare T lymphocyte subpopulations in the blood of healthy Cuban adults. Sex differences found for some phenotypes suggest the need for different reference values for women and men.

Quality control of the total lymphocyte count parameter obtained from routine haematology analyzers, and its relevance in HIV management.

Lylmphocyte subsets/CD4 T Helper cell enumeration in HIV care and treatment in resource constrained settings can be difficult to ascertain as a result of the lack of the necessary instrumentation, capacity and infrastructure. However. it is imperative to gain such information for patient monitoring in HIV. The Total Lymphocyte Count (TLC) is useful as a surrogate marker for CD4 count as recommended by the World Health Organisation (WHO) and to calculate CD4% for pacdiatric use. This study therefore sets out to determine and compare the accuracy of the total lymphocyte counts obtained from three haematology analysers designated A. B and C. that are in regular use for routine haemnatological parameters at the main referral hospital in Barbados. West Indies. The TLC of 263 HIV treatment naive individuals attending the HIV Reference Unit in Barbados were enumnerated on the three haematology analysers. The lymphosumn (Sum of lymphocyte subsets: T-helper cell. T-cytotoxic cells. B lymphocytes and Natural killer cells) should be equal to the TLC. and is derived by immunophenotypic analysis on a 4-colour flowcytometer. Machine C had the highest positive correlation between the TLC and the lymphosumn with and R' of 0.9031 compared to machine A with an R values of 0.7119 and Machine B with R(2) values of 0.637. These results show that there can be dramatic inaccuracies when using routine haematology analysers for both routine use. as a surrogate marker of CD4 or for derivation of CD4% in HIV management. It further demonstrates that all haematology analyzers require some form of Quality control. The possible lack of accuracy of the TLC by haematology analysers should be taken into consideration when following the recommendations of the WHO in resource poor settings or using it as a denominator for calculating CD4%.