The serum immunoglobulin levels are used routinely in clinical practice because they provide key information on the humoral immune status. This study aimed to determine the age-related reference values of serum immunoglobulin levels in healthy children. A total of 330 healthy children, aged between 0 and 18 years, were included in this study. The serum immunoglobulin levels were measured using a nephelometric method in a total of 11 groups, each group consisting of 30 individuals, and IgG subclasses in 6 groups of children aged more than 2 years. The serum IgG levels were high during the newborn period, decreased until the sixth month, and again increased to a maximum level at the age of 18 years. The level of IgA was found to be extremely low in the newborn period and then increased with age. While the lowest value was in the newborn period for serum IgM level, the highest value was in the 16- to 18-year-old period. The IgG subclasses varied depending on the age groups. The updated reference intervals of immunoglobulin levels in children may be used for the accurate diagnosis of immune deficiencies.

Increased levels of acute‐phase reactants and lymphopenia are predictors of disease severity in coronavirus disease 2019 (COVID‐19). This study aimed to investigate the role of apoptosis in the etiology of lymphopenia in patients with COVID‐19. This multicentered, prospective, and case‐control study was conducted with polymerase chain reaction (+) severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) patients, and an age–gender‐matched control group. Samples were taken at the time of diagnosis and analyzed via flow cytometry within 24 h. The participants' demographic data and initial laboratory tests were also recorded. In total, 33 patients with COVID‐19 (mean age = 45.4 ± 17.2) and 25 controls (mean age = 43.4 ± 17.4) participated in the study. All patients were identified as having mild (16), moderate (5), or severe (12) disease severity. Both early and late apoptotic cells in B and T lymphocytes were increased in all patients with COVID‐19 (p < .05). Early apoptotic (EA) B and T lymphocytes were also higher in severe cases compared to mild cases (p = .026). There was no significant difference between lymphopenia and apoptosis in patients with COVID‐19. However, patients with lymphopenia (n = 14) and severe COVID‐19 (p = .013) had increased EA T lymphocytes. This study's results show that B and T lymphocytes' apoptosis increases in patients with COVID‐19. In addition, enhanced T lymphocyte apoptosis is associated with disease severity in lymphopenic patients with COVID‐19.

Background: Genetic deficiencies of immune system, referred to as inborn errors of immunity (IEI), serve as a valuable model to study human immune responses. In a multicenter prospective cohort, we evaluated the outcome of SARS‐CoV‐2 infection among IEI subjects and analyzed genetic and immune characteristics that determine adverse COVID‐19 outcomes.Methods: We studied 34 IEI patients (19M/15F, 12 [min: 0.6‐max: 43] years) from six centers. We diagnosed COVID‐19 infection by finding a positive SARS‐CoV‐2 PCR test (n = 25) and/or a lung tomography scoring (CORADS) ≥4 (n = 9). We recorded clinical and laboratory findings prospectively, fitted survival curves, and calculated fatality rates for the entire group and each IEI subclass.Results: Nineteen patients had combined immune deficiency (CID), six with predominantly antibody deficiency (PAD), six immune dysregulation (ID), two innate immune defects, and one in the autoinflammatory class. Overall, 23.5% of cases died, with disproportionate fatality rates among different IEI categories. PAD group had a relatively favorable outcome at any age, but CIDs and IDs were particularly vulnerable. At admission, presence of dyspnea was an independent risk for COVID‐related death (OR: 2.630, 95% CI; 1.198–5.776, p < .001). Concerning predictive roles of laboratory markers at admission, deceased subjects compared to survived had significantly higher CRP, procalcitonin, Troponin‐T, ferritin, and total‐lung‐score (p = .020, p = .003, p = .014, p = .013, p = .020; respectively), and lower absolute lymphocyte count, albumin, and trough IgG (p = .012, p = .022, p = .011; respectively).Conclusion: Our data disclose a highly vulnerable IEI subgroup particularly disadvantaged for COVID‐19 despite their youth. Future studies should address this vulnerability and consider giving priority to these subjects in SARS‐Cov‐2 therapy trials.

This study analyzed peripheral blood lymphocyte subsets to determine their role in the etiopathogenesis of IGM. This study includes 51 pathologically proven IGM patients (active disease: 26 and in remission: 25) and 28 healthy volunteers. The analyses of lymphocyte subsets were performed by flow cytometric immunophenotyping. The percentage of T helper lymphocyte of the all IGM patients were lower than control groups (p = .001). Absolute cytotoxic T lymphocyte count (p=.03), both percentage (p=.035) and absolute count (p=.002) of the natural killer cells, and both percentage (p=.038) and absolute count (p=.008) of the naturel killer T cells were higher than control group. The percentage of the T helper lymphocyte of the patients with active disease was lower than control group (p = .0003). Absolute cytotoxic T lymphocyte (p=.029) and natural killer T cells (p=.012) of the patients with active disease were higher than control group. Idiopathic granulomatous mastitis is defined as a localized form of granulomatous disorders. However, the observed changes in T cells, NK and NKT cells suggested that there is systemic immune dysregulation in patients with IGM.