The Impact of Absolute CD4 Count and Percentage Discordance on Pneumocystis Jirovecii Pneumonia Prophylaxis in HIV-Infected Patients

Metrological traceability in flow cytometry? Evaluation of a new volumetric method for lymphocyte subsets

INTRODUCTION

Lymphocyte subset enumeration by flow cytometry is important for the therapeutic monitoring of a range of conditions. However, current bead-based methodologies do not produce metrologically traceable results. Here we compare an established bead-based methodology with a volumetric-based system traceable to an internationally recognised reference method.

METHOD

A total of 118 samples received for lymphocyte subset analysis were tested using an established bead-based technique (BD Multitest™ 6-colour TBNK assay using Trucount™ tubes on a BD FACSLyric flow cytometer), followed by a volumetric method on the Sysmex XF-1600 flow cytometer using Exbio Kombitest 6-colour TBNK reagent. All samples were tested in accordance with the manufacturer's instructions.

RESULTS

Absolute count values from both methodologies for CD3+, CD3 + CD4+, CD3 + CD8+, CD19+ and CD3-CD16+/CD56+ lymphocyte populations were compared using linear regression (R2 for all parameters >0.95) and Bland-Altman analysis. There was no significant bias (where p < 0.05) for absolute CD3 + CD4+ lymphocytes in the defined therapeutic range of 0-250 cells/μL (mean bias: 0.27 cells/μL). Although positive biases were seen for CD3 + CD4+ lymphocytes (over the entire range tested: 14-1798 cells/μL) and CD3-CD16+/CD56+ lymphocytes (mean bias: 10.83 cells/μL and 6.79 cells/μL, respectively). Negative biases were seen for CD3 + CD8+ and CD19+ lymphocytes (mean bias: -29.17 cells/μL and - 18.76 cells/μL, respectively).

CONCLUSION

A high degree of correlation was found for results from both methodologies and observed bias was within the limits of clinical acceptability for all populations. This shows that the metrologically traceable lymphocyte subset absolute counts produced by the Sysmex XF-1600 are robust within clinically required limits.

Comment on "Pneumocystis jirovecii Pneumonia in a HIV-Infected Patient with a CD4 Count Greater Than 400 Cells/μL and Atovaquone Prophylaxis"

Collapse

Case Report: Successful treatment of severe pneumocystis carinii pneumonia in a case series of primary nephrotic syndrome after receiving anti-CD20 monoclonal antibody therapy

Rituximab is emerging as a new steroid sparing agent in children with difficult-to-treat nephrotic syndrome due to its ability of depleting CD20-positive B cells. Life-threatening adverse events such as pneumocystis carinii pneumonia may occur even though it seems to be well tolerated. Since rituximab is wildly used in immune-mediated diseases, it is important to manage its severe adverse events. To explore the importance of early diagnosis and treatment of pneumocystis carinii pneumonia in children with primary nephrotic syndrome (PNS) after receiving rituximab therapy, we retrospectively analyzed the clinical data of PNS patients younger than 18 years old with pneumocystis carinii pneumonia who were hospitalized in our center. Clinical features and laboratory test results were retrieved from the electronic medical records. Severe pneumocystis carinii pneumonia occurred in one child with steroid resistant nephrotic syndrome and two with steroid dependent nephrotic syndrome patients after rituximab treatment. These patients were diagnosed in time by metagenomic next-generation sequencing (mNGS) for pathogen detection. Fortunately, all three patients survived after antifungal treatment and achieved complete remission eventually. In conclusion, early diagnosis by using mNGS and timely antifungal treatment is the key to successful management of pneumocystis carinii pneumonia in children with difficult-to-treat PNS.

Impact of human immunodeficiency virus on pulmonary vascular disease

With the advent of anti-retroviral therapy, non-AIDS-related comorbidities have increased in people living with HIV. Among these comorbidities, pulmonary hypertension (PH) is one of the most common causes of morbidity and mortality. Although chronic HIV-1 infection is independently associated with the development of pulmonary arterial hypertension, PH in people living with HIV may also be the outcome of various co-morbidities commonly observed in these individuals including chronic obstructive pulmonary disease, left heart disease and co-infections. In addition, the association of these co-morbidities and other risk factors, such as illicit drug use, can exacerbate the development of pulmonary vascular disease. This review will focus on these complex interactions contributing to PH development and exacerbation in HIV patients. We also examine the interactions of HIV proteins, including Nef, Tat, and gp120 in the pulmonary vasculature and how these proteins alter the endothelial and smooth muscle function by transforming them into susceptible PH phenotype. The review also discusses the available infectious and non-infectious animal models to study HIV-associated PAH, highlighting the advantages and disadvantages of each model, along with their ability to mimic the clinical manifestations of HIV-PAH.

Age, absolute CD4 count, and CD4 percentage in relation to HPV infection and the stage of cervical disease in HIV-1-positive women

A subgroup of women who are co-infected with human immunodeficiency virus type 1 (HIV-1) and human papillomavirus (HPV), progress rapidly to cervical disease. We characterized HPV genotypes within cervical tumor biopsies, assessed the relationships of cervical disease stage with age, HIV-1 status, absolute CD4 count, and CD4 percentage, and identified the predictive power of these variables for cervical disease stage in a cohort of South African women.We recruited 181 women who were histologically diagnosed with cervical disease; 87 were HIV-1-positive and 94 were HIV-1-seronegative. Colposcopy-directed tumor biopsies were confirmed by histology and used for genomic DNA extraction. The Roche Linear Array HPV genotyping test was used for HPV genotyping. Peripheral whole blood was used for HIV-1 rapid testing. Fully automated FC500MPL/CellMek with PanLeucogate (PLG) was used to determine absolute CD4 count, CD4 percentage, and CD45 count. Chi-squared test, a logistic regression model, parametric Pearson correlation, and ROC curves were used for statistical analyses. We used the Benjamini-Horchberg test to control for false discovery rate (FDR, q-value). All tests were significant when both P and q were <.05.Age was a significant predictor for invasive cervical cancer (ICC) in both HIV-1-seronegative (P < .0001, q < 0.0001) and HIV-1-positive women (P = .0003, q = 0.0003). Sixty eight percent (59/87) of HIV-1-positive women with different stages of cervical disease presented with a CD4 percentage equal or less than 28%, and a median absolute CD4 count of 400 cells/μl (IQR 300-500 cells/μl). Of the HIV-1-positive women, 75% (30/40) with ICC, possessed ≤28% CD4 cells vs 25% (10/40) who possessed >28% CD4 cells (both P < .001, q < 0.001). Furthermore, 70% (28/40) of women with ICC possessed CD4 count >350 compared to 30% (12/40) who possessed CD4 count ≤ 350 (both P < .001, q < 0.001).Age is an independent predictor for ICC. In turn, development of ICC in HIV-1-positive women is independent of the host CD4 cells and associates with low CD4 percentage regardless of absolute CD4 count that falls within the normal range. Thus, using CD4 percentage may add a better prognostic indicator of cervical disease stage than absolute CD4 count alone.

High incidence of Pneumocystis jirovecii pneumonia in allogeneic hematopoietic cell transplant recipients in the modern era

BACKGROUND

International guidelines for Pneumocystis jirovecii pneumonia (PJP) prevention recommend prophylaxis for ≥6 months following allogeneic hematopoietic cell transplantation, and longer in patients with graft-versus-host disease (GVHD) or on immunosuppressive therapy (IST). These recommendations are based on cohorts of patients who did not routinely receive anti-thymocyte globulin (ATG) for GVHD prophylaxis.

METHODS

We performed a retrospective chart review of 649 patients, all of whom received ATG as part of GVHD prophylaxis.

RESULTS

The cumulative incidence of definite PJP was 3.52% at both 3 and 5 years (median follow up, 1648 days for survivors). PJP occurred in 13 non-GVHD patients between days 207 and 508, due in part to low CD4 T-cell counts (<200 CD4 T cells/µL). PJP occurred in eight GVHD patients between days 389 and 792, due in part to non-adherence to PJP prophylaxis guidelines (discontinuation of PJP prophylaxis at <3 months after discontinuation of IST). Breakthrough PJP infection was not observed in patients receiving prophylaxis with cotrimoxazole, dapsone or atovaquone, whereas three cases were observed with inhaled pentamidine.

DISCUSSION

In conclusion, for non-GVHD patients receiving ATG-containing GVHD prophylaxis, 6 months of PJP prophylaxis is inadequate, particularly if the CD4 T-cell count is <200 cells/µL or if there is a high incidence of PJP in the community. For patients with GVHD receiving ATG-containing GVHD prophylaxis, continuing PJP prophylaxis until ≥3 months post-discontinuation of IST is important. Cotrimoxazole, dapsone and atovaquone are preferred over inhaled pentamidine.

Predominantly Antibody-Deficient Patients With Non-infectious Complications Have Reduced Naive B, Treg, Th17, and Tfh17 Cells

Background: Patients with predominantly antibody deficiency (PAD) suffer from severe and recurrent infections that require lifelong immunoglobulin replacement and prophylactic antibiotic treatment. Disease incidence is estimated to be 1:25,000 worldwide, and up to 68% of patients develop non-infectious complications (NIC) including autoimmunity, which are difficult to treat, causing high morbidity, and early mortality. Currently, the etiology of NIC is unknown, and there are no diagnostic and prognostic markers to identify patients at risk.

Objectives: To identify immune cell markers that associate with NIC in PAD patients.

Methods: We developed a standardized 11-color flow cytometry panel that was utilized for in-depth analysis of B and T cells in 62 adult PAD patients and 59 age-matched controls.

Results: Nine males had mutations in Bruton's tyrosine kinase (BTK) and were defined as having X-linked agammaglobulinemia. The remaining 53 patients were not genetically defined and were clinically diagnosed with agammaglobulinemia (n = 1), common variable immunodeficiency (CVID) (n = 32), hypogammaglobulinemia (n = 13), IgG subclass deficiency (n = 1), and specific polysaccharide antibody deficiency (n = 6). Of the 53, 30 (57%) had one or more NICs, 24 patients had reduced B-cell numbers, and 17 had reduced T-cell numbers. Both PAD–NIC and PAD+NIC groups had significantly reduced Ig class-switched memory B cells and naive CD4 and CD8 T-cell numbers. Naive and IgM memory B cells, Treg, Th17, and Tfh17 cells were specifically reduced in the PAD+NIC group. CD21^lo B cells and Tfh cells were increased in frequencies, but not in absolute numbers in PAD+NIC.

Conclusion: The previously reported increased frequencies of CD21^lo B cells and Tfh cells are the indirect result of reduced naive B-cell and T-cell numbers. Hence, correct interpretation of immunophenotyping of immunodeficiencies is critically dependent on absolute cell counts. Finally, the defects in naive B- and T-cell numbers suggest a mild combined immunodeficiency in PAD patients with NIC. Together with the reductions in Th17, Treg, and Tfh17 numbers, these key differences could be utilized as biomarkers to support definitive diagnosis and to predict for disease progression.