Plasmodium falciparum‐specific antibodies tend to be short‐lived, but their cognate memory B cells (MBCs) circulate in the peripheral blood of exposed subjects for several months or years after the last infection. However, the time course of antigen‐specific antibodies and B‐cell responses to the relatively neglected parasite Plasmodium vivax remains largely unexplored. Here, we showed that uncomplicated vivax malaria elicits short‐lived antibodies but long‐lived MBC responses to a major blood‐stage P vivax antigen, apical membrane protein 1 (PvAMA‐1), in subjects exposed to declining malaria transmission in the Amazon Basin of Brazil. We found that atypical (CD19+CD10−CD21−CD27−) MBCs, which appear to share a common precursor with classical MBCs but are unable to differentiate into antibody‐secreting cells, significantly outnumbered classical MBCs by 5:1 in the peripheral blood of adult subjects currently or recently infected with P vivax and by 3:1 in healthy residents in the same endemic communities. We concluded that malaria can drive classical MBCs to differentiate into functionally impaired MBCs not only in subjects repeatedly exposed to P falciparum, but also in subjects living in areas with low levels of P vivax transmission in the Amazon, leading to an impaired B‐cell memory that may affect both naturally acquired and vaccine‐induced immunity.

BackgroundCutaneous leishmaniasis (CL) is caused by Leishmania (Viannia) braziliensis, which infects dermal macrophages and dendritic cells, causing an intense immune-mediated-tissue inflammation and a skin ulcer with elevated borders that can heal spontaneously or after antimonial therapy. The resolution of lesions depends on an adaptive immune response, and cytotoxic cells seem to have a fundamental role in this process. The aim of this study is to better understand the role of cytotoxicity mediated mechanisms that occur during the immune response in the CL lesion milieu, considering distinct cytotoxic-related CD107a+ cells, such as CD8+, CD4+, CD4neg CD8neg (double-negative, DN) and CD4+CD8+ (double-positive, DP) T lymphocytes, as well as NK and NKT cells.MethodsLesion derived cells were assessed for T cell subpopulations and NK cells, as well as CD107a expression by flow cytometry. In addition, cytometric bead array (CBA) was used to quantify cytokines and granzyme B concentrations in supernatants from macerated lesions.ResultsFlow cytometry analyses revealed that NKT cells are the major CD107a-expressing cell population committed to cytotoxicity in CL lesion, although we also observed high frequencies of CD4+ and DN T cells expressing CD107a. Analysing the pool of CD107a+-cell populations, we found a higher distribution of DN T cells (44%), followed by approximately 25% of NKT cells. Interestingly, NK and CD8+ T cells represented only 3 and 4% of the total-CD107a+-cell pool, respectively.ConclusionsThe cytotoxicity activity that occurs in the lesion milieu of CL patients seems to be dominated by DN T and NKT cells. These findings suggest the need for a reevaluation of the role of classical-cytotoxic NK and CD8+ T cells in the pathogenesis of CL, implicating an important role for other T cell subpopulations.

Cutaneous leishmaniasis (CL) is an important public health issue worldwide. The control of Leishmania infection depends on cellular immune mechanisms, and the inflammatory response may contribute to pathogenesis. A beneficial role of CD8(+) T lymphocytes has been proposed; nevertheless, other studies suggest a cytotoxic role of CD8(+) T lymphocytes involved in tissue damage, showing controversial role of these cells. The goal of the current study was to understand the immunopathology of CL and determine the profile of cytotoxic cells--such as CD4(+) T, natural killer and natural killer T cells--that might be involved in triggering immunological mechanisms, and may lead to cure or disease progression. The frequencies of cytotoxic cell populations in peripheral blood, obtained from patients with active disease, during treatment and after clinical healing, were assessed by flow cytometry. Cytotoxicity could not be related to a deleterious role in Leishmania braziliensis infection, as patients with active CL showed similar percentages of degranulation to healthy individuals (HI). Cured patients exhibited a lower percentage of degranulating cells, which may be due to a downregulation of the immune response. The understanding of the immunopathological mechanisms involved in CL and the commitment of cytotoxic cells enables improvements in therapeutic strategies.

BackgroundLeishmaniasis is an important parasitic disease affecting millions worldwide. Human cutaneous leishmaniasis (CL) is endemic in Rio de Janeiro, Brazil, where is caused by Leishmania braziliensis. The adaptive immune response is accountable for the healing of CL and despite of key role of CD8+ T cells in this immune response little is known about the CD8+ T lymphocytes frequencies, apoptosis and antigen-responsive CD8+ T lymphocytes of CL patients during antimonial therapy.MethodsUsing flow cytometry, we examined total and effector CD8+ T cells from CL patients before (PBT), during (PDT) and after (PAT) treatment for apoptosis and frequencies upon isolation and after in vitro L. braziliensis antigens (LbAg)-stimulation culture. Besides, a correlation study between immunological findings and lesion size was done.ResultsPDT showed lower frequencies of total CD8+ T lymphocytes and higher levels of apoptosis of these cells, which were also observed following LbAg-stimulation culture. Regarding effector CD8+ T cells, high frequencies were observed in PDT, while lower frequencies were observed in PAT. Interestingly, PDT showed higher frequencies of apoptotic-effector CD8+ T lymphocytes. Similar results were seen after in vitro antigenic-stimulation assays. Correlation analysis showed that the greater the size of lesion, the smaller the frequency of effector CD8+ T lymphocytes in PDT and PAT, as well as a positive correlation between apoptotic-effector CD8+ T cells frequency and lesion size of PDT.ConclusionsChanges in effector CD8+ T–lymphocyte frequencies, during and after treatment, seem to represent a critical stage to generate an efficient immune response and suggest that these cells would be evolved in the triggering or in the resolution of lesion, under the influence of therapy. This hypothesis opens new perspectives to clarify controversial statements about the protective or deleterious role of CD8+ T cells in the cure or aggravation of CL and the new approach of evaluating patients during treatment proved to be of utmost importance for understanding the immune response in the healing process of human CL.

These results show that cell phenotyping by flow cytometry could be an effective tool for determining leukocyte profiles in saliva samples from patients with CP and healthy individuals.

The pathogenesis of cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is dictated mainly by the immune-mediated-tissue inflammation developed. The understanding of the immunological mechanisms that generate tissue damage or resolution of lesions is the key to the development of effective vaccine protocols and proper therapeutic schemes. It is clear that the specific immune response mediated by T cells is responsible for the beneficial outcome of the disease, however, the roles of CD4 + T, CD8 + T, NK and NKT cell subpopulations in immunopathogenesis of CL need to be elucidated. Peripheral blood cells from patients before, during and after the antimonial therapy, as well as healthy individuals (HI) were cultured with (LbAgS) or without (NS) L. braziliensis antigens (LbAg). Afterwards, the frequencies of LbAg-specific-cytotoxic CD8 + T, CD4 + T, NK and CD3 + CD56 + NKT cells, as well as their activation and exhaustion profiles, were defined by flow cytometry. We observed higher frequencies of CD8 + T, NK and CD3 + CD56 + NKT cells and lower frequencies of CD4 + T lymphocytes in LbAgS cell cultures from patients before treatment. The specific response to LbAg resulted in an expansion of cytotoxic-activated CD4 + T, CD8 + T, and NK cells, before and during treatment, indicating specificity in the response by these cells against L. braziliensis. Furthermore, comparing the differences of frequencies of cytotoxic-activated CD4 + T, CD8 + T, and NK cells, among before and during treatment patients and HI groups, we conclude that these cell populations are in charge of immune response elicited by antimonial therapy. Interestingly, we also observed that NK

In human cutaneous leishmaniasis (CL), the immune response is mainly mediated by T-cells. The role of CD8+ T-lymphocytes, which are related to healing or deleterious functions, in affecting clinical outcome is controversial. The aim of this study was to evaluate T-cell receptor diversity in late-differentiated effector (LDE) and memory CD8+ T-cell subsets in order to create a profile of specific clones engaged in deleterious or protective CL immune responses. Healthy subjects, patients with active disease (PAD) and clinically cured patients were enrolled in the study. Total CD8+ T-lymphocytes showed a disturbance in the expression of the Vβ2, Vβ9, Vβ13.2, Vβ18 and Vβ23 families. The analyses of CD8+T-lymphocyte subsets showed high frequencies of LDE CD8+T-lymphocytes expressing Vβ12 and Vβ22 in PAD, as well as effector-memory CD8+ T-cells expressing Vβ22. We also observed low frequencies of effector and central-memory CD8+ T-cells expressing Vβ2 in PAD, which correlated with a greater lesion size. Particular Vβ expansions point to CD8+ T-cell clones that are selected during CL immune responses, suggesting that CD8+ T-lymphocytes expressing Vβ12 or Vβ22 are involved in a LDE response and that Vβ2 contractions in memory CD8+T-cells are associated with larger lesions.

Goal: The aim of this study was to describe the incidence of oral mucositis (OM) in patients undergoing autologous hematopoietic stem cell transplantation (auto-HSCT), relating it to the main clinical factors. Methodology: Descriptive analysis based on a randomized clinical study was conducted with patients undergoing HSCT at the University Hospital of Federal University of Juiz de Fora between January 2018 and June 2019. The World Health Organi­zation oral toxicity scale was used to assess the degree of oral mucositis and adverse events were graded according to the Common Terminology Criteria for Adverse Events (CTCAE) 4.0 version. Results: Thirty-eight patients were evaluated. The incidence of OM and severe oral mucositis (SOM) was 57.9% and 21.0%, respectively. The mean duration of OM was 7.2 ± 2.6 days and the lomustine, etoposide, cytarabine and cyclophosphamide protocol (LEAC) pre­sented the longest mean time 8.1 ± 3.1 days (p-value 0.02). The number of viable CD34+ cells and the onset day of neutropenia were predictors of SOM. Conclusion: The incidence of OM in patients undergoing HSCT was lower than reported in the literature, being more severe in patients who received less CD34+ cells and in patients with early onset of neutropenia.