INTRODUCTION Immunity in cancer patients is modified both by the cancer itself and by oncospecific treatments. Whether a patient’s adaptive immunity is impaired depends on their levels of naive lymphocytes and other cell populations. During the COVID-19 pandemic, cancer patients are at greater risk of progressing to severe forms of the disease and have higher mortality rates than individuals without cancer, particularly while they are receiving cancer-specific therapies. An individual’s protection against infection, their response to vaccines, and even the tests that determine the humoral immune response to SARS-CoV-2, depend on lymphocyte populations, meriting their study.
OBJECTIVE Estimate blood concentrations of lymphocytes involved in the immune response to new pathogens in cancer patients.
METHODS We carried out an analytical study of 218 cancer patients; 124 women and 94 men, 26–93 years of age, who were treated at the National Oncology and Radiobiology Institute in Havana, Cuba, March–June, 2020. Patients were divided into five groups: (1) those with controlled disease who were not undergoing cancer-specific treatment; (2) those undergoing debulking surgery; (3) patients undergoing chemotherapy; (4) patients undergoing radiation therapy and (5) patients currently battling infection. We evaluated the following peripheral blood lymphocyte subpopulations via flow cytometry: B lymphocytes (total, naive, transitional, memory, plasmablasts and plasma cells); T lymphocytes (total, helper, cytotoxic and their respective naive, activated, central memory and effector memory subsets); and total, secretory and cytotoxic natural killer cells and T natural killer cells. We also estimated neutrophil/lymphocyte ratios. Lymphocyte concentrations were associated with controlled disease and standard cancer therapy. For variables that did not fall within a normal distribution, ranges were set by medians and 2.5–97.5 percentiles. The two-tailed Mann–Whitney U test was used to measure the effect of sex and to compare lymphocyte subsets. We calculated odds ratios to estimate lymphopenia risk.
RESULTS All cancer patients had lower values of naive helper and cytotoxic T lymphocyte populations, naive B lymphocytes, and natural killer cells than normal reference medians. Naive helper T cells were the most affected subpopulation. Memory B cells, plasmablasts, plasma cells, activated T helper cells, and cytotoxic central memory T cells were increased. Patients undergoing treatment had lower levels of naive lymphocytes than untreated patients, particularly during radiation therapy. The risk of B lymphopenia was higher in patients in treatment. The odds ratio for B lymphopenia was 8.0 in patients who underwent surgery, 12.9 in those undergoing chemotherapy, and 13.9 in patients in radiotherapy.
CONCLUSIONS Cancer and conventional cancer therapies significantly affect peripheral blood B lymphocyte levels, particularly transitional T helper lymphocytes, reducing the immune system’s ability to trigger primary immune responses against new antigens.
KEYWORDS Cancer, lymphocyte subsets, flow cytometry, immunity, virus diseases, Cuba
INTRODUCTION Advanced age and chronic disease comorbidities are indicators of poor prognosis in COVID-19 clinical progression. Fatal outcomes in patients with these characteristics are due to a dysfunctional immune response. Understanding COVID-19’s immunopathogenesis helps in designing strategies to prevent and mitigate complications during treatment.
OBJECTIVE Describe the main immunopathogenic alterations of COVID-19 in patients of advanced age or with chronic non-communicable diseases. DATA
ACQUISITION We carried out a bibliographic search of primary references in PubMed, Elsevier, Science Direct and SciELO. A total of 270 articles met our initial search criteria. Duplicate articles or those unrelated to at least one chronic comorbidity, senescence or inflammation and those that studied only patient clinical characteristics, laboratory tests or treatments were excluded. Finally, our selection included 124 articles for analysis: 10 meta-analyses, 24 original research articles, 67 review articles, 9 editorials, 9 comments, 3 books and 2 websites.
DEVELOPMENT Hypertension and diabetes mellitus are the most common comorbidities in COVID-19 patients. Risk of developing severe manifestations of the disease, including death, is increased insenescent and obese patients and those with cardiovascular disease, cancer or chronic obstructive pulmonary disease. Low-grade chronic inflammation is characteristic of all these conditions, reflected in a pro-inflammatory state, endothelial dysfunction, and changes to innate immunity; mainly of the monocyte-macrophage system with changes in polarization, inflammation, cytotoxicity and altered antigenic presentation. In the case of SARS-CoV-2 infection, mechanisms involved in acute inflammation overlap with the patient’s pro-inflammatory state, causing immune system dysfunction. SARS-CoV-2 infection amplifies already-existing alterations, causing failures in the immune system’s control mechanisms. The resulting cytokine storm causes an uncontrolled systemic inflammatory response marked by high serum levels of inflammatory biomarkers and a pro-inflammatory cytokine profile with decompensation of underlying diseases. In asthma, chronic eosinophilic inflammation protects against infection by producing a reduced interferon-mediated response and a reduced number of ACE2 receptors.
CONCLUSIONS Low-grade chronic inflammation present in advanced age and chronic diseases—but not in bronchial asthma—produces a pro-inflammatory state that triggers a dysregulated immune response, favoring development of severe forms of COVID-19 and increasing lethality.
KEYWORDS SARS-CoV-2, COVID-19, inflammation, aging, chronic disease, immune system
INTRODUCTION Double-negative T lymphocytes act as immunomodulators in immune response. This subpopulation is rare in blood but important in the immunopathogenesis of autoimmune diseases, viral infections, cancer and transplant rejection. These disorders have been studied in Cuba using flow cytometry, but normal values of these cells have not yet been established.
OBJECTIVE Estimate preliminary reference values for double-negative T lymphocytes according to sex and age in Cuban adults.
METHODS A cross-sectional study was carried out in a population of 182 healthy adult residents of Havana: 93 women and 89 men aged 18–80 years with no chronic diseases, toxic habits (smoking, excessive alcohol or caffeine intake) or medications that might alter quantity or functioning of immune-system cells. Peripheral blood was drawn to determine immunophenotype with monoclonal antibodies. The phenotype of double-negative T lymphocytes was quantified as CD45+/CD3+/CD4–/CD8–/CD56–using a Gallios flow cytometer (Beckman-Coulter, France). Medians and ranges (to the 5th and 95th percentiles) were calculated for sex and age, for both percentages and absolute values. To evaluate the effects of sex and age, both variables as well as their interaction were included in a linear model.
RESULTS Respective median and range values were total percentage values 3.4 (1.6–7.4) and total absolute values (cells/μL) 57.5 (23.0–157.0). The effect of age on lymphocyte values (percentage and absolute) was significant, with lower numbers in the 51–80 years’ age group (p <0.001). Percentage values according to age group were: 18–25 years, 3.8 (2.2–7.4); 26–50 years, 3.7 (1.7–8.7); and 51–80 years 2.6 (1.3–6.6). Absolute values by age group were: 18–25 years, 90 (32.6–163.7); 26–50 years, 65 (28.8–184.0); and 51–80 years 38.5 (17.9–90.1). Desegregating data by sex and age: percentage of women aged 18–25 years 5.2 (2.1–7.8), 26–50 years 4.0 (1.8–7.7), and 51–80 years 2.5 (1.3–5.8); percentage of men aged 18–25 years 3.4 (2.3–7.3), 26–50 years 3.8 (1.5–8.7), and 51–80 years 2.6 (1.2–7.3). Absolute values: women aged 18–25 years 112.0 (40.0–153.1), 26–50 years 67.0 (26.7–138.3), and 51–80 years 40 (18.6–92.0); and men aged 18–25 years 71.5 (32.1–166.7), 26–50 years 61.5 (29.9–188.7), and 51–80 years 36 (13.5–81.7). The low sex*age interaction confirms these differences occur in both men and women. Values decrease with age, with a more abrupt fall starting at 50 years.
CONCLUSIONS Estimated reference values were determined for absolute values and relative proportions of double-negative T lymphocytes in healthy Cuban adults according to sex and age. Age was found to have a significant effect.
KEYWORDS Reference values, T lymphocytes, flow cytometry, immunology, Cuba
INTRODUCTION Quantification of lymphocyte subpopulations is useful for evaluating immune response in states of health and disease, including immunodeficiencies, autoimmunity, infections and cancer. Studies have found that concentrations and proportions of different cell subpopulations vary with geographic location, age, sex and ethnicity. Knowing the normal values of these cells and their variation in healthy populations will contribute to improved clinical practice and scientific research.
OBJECTIVE Estimate normal absolute concentrations and percentages of the most abundant lymphocyte subpopulations in peripheral blood and their relation to sex and age.
METHODS A cross-sectional analysis was conducted in 129 healthy adults, 61 men and 68 women aged 18–80 years; 89 aged <50 years and 40 ≥50 years. We included individuals who agreed to participate by written informed consent. Exclusion criteria were chronic disease, or use of tobacco, alcohol or medications that can alter immune system cell numbers and functions.
Through dual platform flow cytometry, we determined absolute and percentage values for T lymphocyte subsets CD3+, CD3+/CD4+T, CD3+/CD8+T, CD19+ B cells and CD3-/CD56+ natural killer cells in peripheral blood, using an 8-color flow cytometer. We estimated medians and the 2.5 and 97.5 percentiles and calculated the Pearson correlation coefficient to evaluate associations. Significance tests were also used to compare groups. The significance threshold was p = 0.05 in all cases.
RESULTS Ranges of absolute values and percentages (%) were: total lymphocytes: 1200–3475 cells/μL (20.2–49.3); CD3+ T cells: 880–2623 cells/μL (56.5–84.7); CD3+/CD4+ T cells: 479–1792 cells/μL (30.3–55.7); CD3+/CD8+ T cells: 248–1101 cells/μL (13.2–42.9); CD19+ B cells: 114–1491 cells/μL (5.4–49.5); CD3-/CD56+ natural killer cells: 70–652 cells/μL (3.7–28.0); and the CD4+:CD8+ index: 0.80–3.92. Absolute numbers––but not percentages––of lymphocytes and CD3+ T cells were higher in those <50 years (p = 0.025 and 0.020, respectively). Absolute values and relative percentages of CD3+/CD8+ and relative values of CD3+/ CD4+ T cells were significantly higher in the younger subgroup (p = 0.004 and p = 0.047). Age was not associated significantly with B lymphocytes or natural killer cells. Absolute and relative values of CD3+/CD4+ T lymphocytes were significantly higher in women (p = 0.009 and 0.036, respectively).
CONCLUSIONS. Absolute numbers of total lymphocytes and T and CD3+/CD8+ T lymphocytes are higher in younger individuals. In percentage values, CD3+/CD4+ T lymphocytes are lower in older persons. Absolute and percentage values of CD3+/CD4+ T phenotype are higher in women. These differences justify adjusting clinical analyses to different values by age and sex.
KEYWORDS T lymphocytes, B lymphocytes, normal values, flow cytometry, age, sex, Cuba
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.
KEYWORDS Normal values, T-lymphocyte subpopulations, flow cytometry, Cuba
