Background: Lymphopenia is associated with various pathologies such as sepsis, burns, trauma, general anesthesia and major surgeries. All these pathologies are clinically expressed by the so-called Systemic Inflammatory Response Syndrome which does not include lymphopenia into defining criteria. The main objective of this work was to analyze the diagnosis of patients admitted to a hospital related to lymphopenia during hospital stay. In addition, we investigated the relationship of lymphopenia with the four levels of the Severity of Illness (SOI) and the Risk of Mortality (ROM).Method and findings: Lymphopenia was defined as Absolute Lymphocyte Count (ALC) <1.0 x10⁹/L. ALC were analyzed every day since admission. The four levels (minor, moderate, major and extreme risk) of both SOI and ROM were assessed. A total of 58,260 hospital admissions were analyzed. More than 41% of the patients had lymphopenia during hospital stay. The mean time to death was shorter among patients with lymphopenia on admission 65.6 days (CI95%, 57.3–73.8)vs89.9 (CI95%, 82.4–97.4), P<0.001. Also, patients with lymphopenia during hospital stay had a shorter time to the mortality, 67.5 (CI95%, 61.1–73.9)vs96.9 (CI95%, 92.6–101.2), P<0.001.Conclusions: Lymphopenia had a high prevalence in hospitalized patients with greater relevance in infectious pathologies. Lymphopenia was related and clearly predicts SOI and ROM at the time of admission, and should be considered as clinical diagnostic criteria to define SIRS.

Microsporidia are opportunistic intracellular parasites, generating serious pathology in individuals with a compromised immune system. Infection by microsporidia inhibits p53 and Caspase 3, proteins involved in apoptosis and the cell cycle, which are vital in the malignant process of epithelial cells. The presence of microsporidia in the intestinal tissues of 87 colon cancer (CC) patients and 25 healthy controls was analyzed by real-time PCR and an immunofluorescence antibody test. Anti-Encephalitozoon antibodies were analyzed in serum samples by ELISA (enzyme linked immunosorbent assay). In 36 (41.3%) CC cases, microsporidia infections were identified in their tissues vs. no cases among control subjects (p < 0.0001). An increase in IgG and IgE anti-Encephalitozoon antibodies was found in patients with CC, which would demonstrate continuous and previous contact with the parasite. The high prevalence of microsporidia in tissues and the seroprevalence in patients with CC suggest a relationship between microsporidia and the etiopathogenesis of CC.

Downregulation of the T cell system has been proposed as a mechanism to block immunity in colonic cancer (CC). However, little has been studied about circulating αβ and γδ T cells and their immunological status in newly diagnosed patients. The aim of this study was to characterize the αβ and γδ T cell subsets in peripheral blood of patients with CC matched with healthy volunteers. In this prospective case-control study, blood samples were obtained from 96 patients with newly diagnosed treatment-naïve infiltrating colonic adenocarcinoma and 48 healthy volunteers. Pathological report at surgery was obtained from all CC patients. A significant decrease in CD3+ γδ T cells and CD3+CD8+ γδ T cells (p<0.001) were observed in CC patients. Apoptosis was significantly increased in all conventional and both αβ and γδ T cell subsets in patients with CC vs healthy subjects. γδ T cells were decreased in peripheral blood of patients with microscopic infiltration in tissues, history of cancer and synchronous colon cancer (p < 0.05). IFN-γ was significantly reduced in CC patients compared to controls. Cytotoxic effector γδ T cells TEMRA (CD8 and CD56) are the proportionally most abundant T cells in peripheral blood of CC patients. Patients with CC present a deep downregulation in the systemic T-cell immunity. These variations are evident through all tumor stages and suggest that a deficiency in γδ T cell populations could be preventing control of tumor progression. This fact prove the role of immunomodulation on CC carcinogenesis.

BACKGROUND A deficiency of γδ T cells has been described in Crohn's disease (CD). AIM To analyze the gene expression of interleukin 7 (IL-7) and its receptors in the tissues of patients with CD. METHODS We studied the peripheral blood of 80 patients with CD, comparing them with a group of 80 healthy subjects. The number and apoptosis of αβ and γδ T cells in peripheral blood and the proportion of αβ and γδ T cells in the intestinal tissues of patients with CD (n = 25) were studied. The gene and protein expression of IL-7, IL-2 receptor subunit γ [cluster of differentiation 132 (CD132)], receptor α (CD127), and caspase-3 in tissues was analyzed by quantitative PCR. Serum IL-7 levels were also analyzed. RESULTS In patients with CD, a decreased number of γδ T cells and an increase in the apoptosis of CD56+ αβ and γδ T cells in peripheral blood was observed (P < 0.0001 and P < 0.01) respectively, and there was an inverse correlation among T subsets and their apoptosis. In addition, IL-7 gene expression and IL-7 protein in the tissues of these patients were increased. The titers of caspase-3 in tissues were low vs control group (P > 0.01). The percentage of CD8+γδ T cells decreased in tissues (P < 0.01), and was directly related to IL-7 levels in peripheral blood. The expression of IL-2 receptor subunit γ (CD132) was greatly decreased in the tissues of patients with CD (P < 0.05). CONCLUSION There may be a cause-effect relationship between the lower gene expression of the IL-2 receptor subunit γ (CD132) in tissues of patients with CD and γδ T cells immunodeficiency.

Background: The COVID-19 pandemic is the biggest global health problem in the last hundred years. The efficacy of the vaccine to protect against severe disease is estimated to be 70–95% according to the studies carried out, although there are aspects of the immune response to the vaccine that remain unclear. Methods: Humoral and cellular immunity after the administration of three doses of the Pfizer–BioNTech and Oxford AstraZeneca vaccines against SARS-CoV-2 over one year and the appearance of post-vaccination COVID-19 were studied. SARS-CoV-2 IgG and IgA antibodies, αβ and γδ T-cell subsets, and their differentiation stages and apoptosis were analyzed. Results: Anti-SARS-CoV-2 IgG and IgA antibodies showed a progressive increase throughout the duration of the study. This increase was the greatest after the third dose. The highest levels were observed in subjects who had anti-SARS-CoV-2 antibodies prior to vaccination. There was an increase in CD4+ αβ, CD8+ γδ and TEM CD8+ γδ T cells, and a decrease in apoptosis in CD4+ CD8+ and CD56+ αβ and γδ T cells. Post-vaccination SARS-CoV-2 infection was greater than 60%. The symptoms of COVID-19 were very mild and were related to a γδ T cell deficit, specifically CD8+ TEMRA and CD56+ γδ TEM, as well as lower pre-vaccine apoptosis levels. Conclusions: The results unveil the important role of γδ T cells in SARS-CoV-2-vaccine-mediated protection from the disease.