Alterations In Lymphocyte Populations Research Articles

B-cell capacity for differentiation changes with age.

BackgroundAge‐related immune deficiencies are thought to be responsible for increased susceptibility to infection in older adults, with alterations in lymphocyte populations becoming more prevalent over time. The loss of humoral immunity in ageing was attributed to the diminished numbers of B cells and the reduced ability to generate immunoglobulin.AimsTo compare the intrinsic B‐cell capacity for differentiation into mature plasma cells (PCs), between young and old donors, using in vitro assays, providing either effective T‐cell help or activation via TLR engagement.MethodsB cells were isolated from healthy individuals, in younger (30–38 years) and older (60–64 years) donors. An in vitro model system of B‐cell differentiation was used, analysing 5 differentiation markers by flow cytometry, under T‐dependent (TD: CD40/BCR stimulation) or T‐independent (TI: TLR7/BCR activation) conditions. Antibody secretion was measured by ELISA and gene expression using qPCR.ResultsTI and TD differentiation resulted in effective proliferation of B cells followed by their differentiation into PC. B‐cell‐executed TI differentiation was faster, all differentiation marker and genes being expressed earlier than under TD differentiation (day 6), although generating less viable cells and lower antibody levels (day 13). Age‐related differences in B‐cell capacity for differentiation were minimal in TD differentiation. In contrast, in TI differentiation age significantly affected proliferation, viability, differentiation, antibody secretion and gene expression, older donors being more efficient.ConclusionAltogether, B‐cell differentiation into PC appeared similar between age groups when provided with T‐cell help, in contrast to TI differentiation, where multiple age‐related changes suggest better capacities in older donors. These new findings may help explain the emergence of autoantibodies in ageing.

Disrupted Lymphocyte Homeostasis in Hepatitis-Associated Acquired Aplastic Anemia Is Associated with Very Low Telomere Lengths

Acquired aplastic anemia (AA) is a hematologic disorder characterized by low blood counts and a hypocellular bone marrow, caused by autoimmune destruction of early hematopoietic cells. The diagnosis of AA is made by excluding other disorders that can present with bone marrow failure (BMF). Such disorders include dyskeratosis congenita (DC), a multisystem BMF syndrome, caused by an inherited defect in telomere maintenance. Although classical DC presents in childhood with stereotypical mucocutaneous changes, milder forms of telomere dysfunction associated with mutations in TERT and TERC genes can present with non-syndromic bone marrow failure clinically indistinguishable from AA. In clinical practice, lymphocyte telomere length measurements are used as a first-line screen for inherited telomeropathies before initiating treatment for AA.In our BMF center, we have observed that several patients with features of hepatitis-associated AA (HAA) had lymphocyte telomere lengths at diagnosis at or below the first percentile of age-matched controls, in the range similar to inherited telomere disorders. To confirm our initial observation, we performed a retrospective analysis of telomere lengths of consecutively enrolled HAA patients with non-hepatitis associated AA patients in our institution.A total of 30 patients with AA were included in this study: 10 had HAA and 20 had other AA (Table 1). The median age at telomere testing was 8.0 years (range 1-19 years). There was no significant difference in age or disease severity between the two groups (p=0.827). The patients' median lymphocyte telomere length (TL) was significantly lower in the HAA patients compared to AA (7.4kb versus 9.1kb, P= 0.021); the difference remained significant after adjusting for patient age (p<0.001). Strikingly, 5 of 10 HAA patients had telomeres at or below the 1st percentile of age-matched normal controls, within the diagnostic range for telomeropathies (Figure 1A). None of these 5 patients had clinical features of DC. As a comparison, TL measurements of genetically-confirmed DC patients (Figure 1) demonstrated TL below the 1st percentile for age-matched controls, and within a similar range to that seen in the HAA patients. To ensure that the significantly lower telomere lengths in the HAA patients were not caused by an occult TERT or TERC gene mutation, the five HAA patients with TL below the 1st percentile were screened for germline mutations in TERT and TERC. A known heterozygous polymorphism, Ala1062Thr was found in one patient, a known variant with no known telomere defect and no effect on telomere length.Because differences in lymphocyte activation and subset composition are known to impact telomerase activity, we hypothesized that alterations in lymphocyte populations caused by the unique inflammatory state of HAA could partly account for significantly shorter TL in this population. HAA patients exhibited significantly lower absolute lymphocyte counts and lower lymphocyte subsets across the board, as well as the decreased CD4/CD8 ratio compared to non-hepatitis AA patients (Figure 2). The median telomere length in the two groups was significantly correlated with lymphocyte counts (Pearson correlation coefficient 0.52, p=0.003).An altered lymphocyte homeostasis such as the one characteristic for HAA limits the specificity of telomere measurements as a screening method to identify patients with AA due to a genetic defect in telomere maintaining genes. As such, short telomeres in HAA in the absence of other features suggestive for DC does not necessarily warrant genetic testing for telomere length. Longitudinal studies of telomeres and study of clonal hematopoiesis in this population is ongoing.Table 1Overall (n = 30)AA (n=20)HAA (n=10)P value*Patient CharacteristicGender, female n (%)12 (40)9 (45)3 (30)0.694Gender, male n (%)18 (60)11 (55)7 (70)Age at diagnosis, y, median (range)8.0 (1-19)8.3 (1-19)7.5 (3-17)0.827Disease Severity, n (%)0.999Moderate6 (20)4 (20)2 (20)Severe22 (73)15 (75)7 (70)Very Severe2 (7)1 (5)1 (10)Median Lymphocyte Telomere Length, kb (range)8.9 (5.9-11.3)9.1 (7.5-11.3)7.4 (5.9-9.8)0.021≤ 1st percentile of age-matched controls5051-10th percentile of age-matched controls550> 10th percentile of age-matched controls20155*P-values are obtained by Fisher's exact test for gender and disease severity and by Wilcoxon test for age and telomere length. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The influence of paediatric HIV infection on circulating B cell subsets and CXCR5(+) T helper cells.

SummaryAntiretroviral therapy (ART) only partially restores HIV‐induced alterations in lymphocyte populations. We assessed B and T cell phenotypes in a cohort of children from a single centre in the United Kingdom with perinatally acquired HIV compared to healthy controls. The majority of HIV infected children (44 of 56) were on fully suppressive combination ART. Children with perinatally acquired HIV had significantly lower memory B and CD4+CD45RO+CXCR5+ [follicular T helper cell (Tfh)‐like] T cell percentages. Detectable viraemia was associated with higher CD21– (activated and exhausted/tissue‐like memory) B cells. A greater proportion of life spent on suppressive ART was associated with higher memory B cell percentages. These results suggest that early and sustained suppressive ART may preserve B and T cell phenotypes in perinatally acquired HIV and limit deficits in humoral immunity. A lower proportion of circulating Tfh‐like cells in HIV infected children appears to be independent of HIV treatment history and ongoing HIV viraemia and warrants further investigation.

Inhalation ofOrtho-Phthalaldehyde Vapor Causes Respiratory Sensitization in Mice

Ortho-Phthalaldehyde (OPA) has been approved for high-level sterilization of heat-sensitive medical instruments and is increasingly being used as a replacement in the healthcare industry for glutaraldehyde, a known sensitizer. Numerous case reports have been published indicating workers and patients experiencing respiratory problems, anaphylaxis, skin reactivity, and systemic antibody production. Our laboratory previously demonstrated that OPA is a dermal sensitizer in mice. The goal of the present study was to determine if OPA is a respiratory sensitizer following inhalation exposure. Mice were exposed to OPA vapor and airway and lymph nodes were examined for cytokine gene expression and alterations in lymphocyte populations. Inhalation of OPA for 3 days resulted in a concentration-dependent increase in lymphocyte proliferation, mainly B lymphocytes, in the draining lymph nodes. A secondary challenge of mice with OPA resulted in a dramatic increase in the population of B lymphocytes expressing IgE. Expression of Th2 (IL-4, IL-5, and IL-13) and anti/proinflammatory (IL-10, TNFα, and IL-1β) cytokine genes was upregulated in the lymph nodes and the nasal mucosa. Mice exposed to the higher concentrations of OPA-produced OPA-specific IgG1 antibodies indicating systemic sensitization. These findings provide evidence that OPA has the potential to cause respiratory sensitization in mice.

Smoking cessation reverses cigarette smoke-induced impairment of B cell development and skewed CD4:CD8 T cell ratios in mice (36.43)

Abstract Cigarette smoking is a risk factor for developing osteoporosis, and previous studies suggest lymphocytes are required for normal bone homeostasis and peak bone mass. We hypothesized that lymphocyte development is adversely affected by smoke exposure. If so, this outcome would provide a mechanism to partly explain how cigarette smoking promotes osteoporosis. To test this possibility, we investigated how the duration and cessation of cigarette smoke exposure affected the development, distribution, and function of lymphocytes normal mice. Consistent with the hypothesis, 3-12 weeks of smoke exposure significantly diminished bone marrow B220+CD43- B cell subsets, but, interestingly, did not significantly affect earlier progenitor B220+CD43+ B cells or thymic T cell subsets. In the spleen, by contrast, we find that individual splenic B cell populations, including transitional, marginal zone, and follicular mature B cell subsets, were largely unaffected by smoke exposure, but smoking did skew splenic CD4+:CD8+ T cell ratio to favor CD8+ T cells compared to sham controls. However, smoke exposure also had little or no effect on lymphocyte function ex vivo. Interestingly, smoking-induced alterations in lymphocyte populations observed at 12 weeks were lost when smoke exposure was stopped for six weeks. These data provide evidence that smoke exposure causes significant changes in lymphocyte populations that can largely be reversed after six weeks without smoking.

Changes of Lymphocyte Populations in Pediatric Steroid-Sensitive Nephrotic Syndrome Are More Pronounced in Remission than in Relapse

Background/Aim: Although clinical and immunological findings in steroid-sensitive nephrotic syndrome (SSNS) favor an immunopathogenesis, many issues remain unsolved. Comprehensive studies analyzing cellular and humoral immunity in SSNS are scarce, and few studies addressed the effect of steroids on immunological factors. Methods: We therefore performed a cross-sectional study of T and B lymphocyte populations in 89 children during the different stages of the disease and related the findings to parameters of humoral immunity and treatment with steroids. Results: In untreated relapse, an increase in the proportion of activated CD3+ lymphocytes with a concomitant reduction of CD19+ B cells was noted compared to healthy controls. Conversely, patients with steroid dependency, relapsing on alternate-day steroids, showed a decline of the absolute numbers as well as proportion of CD4+ lymphocytes but a relative increase in CD19+ B cells, compared to healthy controls. Also untreated remission was characterized by an absolute and relative decrease in CD4+ lymphocytes compared to healthy controls which was accompanied by a significant increase in the proportion of CD8+ and also activated CD3+ lymphocytes. Steroid-induced remission resulted in suppression of absolute and relative CD4+, while absolute and relative B cells were upregulated in this group compared to untreated remission. Summary and Conclusion: Alterations of lymphocyte populations in SSNS are not limited to relapse but seem to be more pronounced in remission and show a different profile with steroid treatment. Changes of lymphocyte populations do not only affect T but also B lymphocytes, which may be of relevance in the pathogenesis of this disorder.

Humoral Response Suppression Observed with CD23 Transgenics

CD23, also known as the low affinity IgE receptor (FcepsilonRII), has been hypothesized to have a role in IgE regulation. A new CD23 transgenic mouse was generated using the MHC class I promoter and IgH enhancer to further test the hypothesis that CD23 plays a role in the down-regulation of IgE. Study of three founder lines by FACS showed overexpression to varying extents on both B and T lymphocytes. No alterations in lymphocyte populations was observed. All three founder lines exhibited strong suppression of IgE in response to DNP-keyhole limpet hemocyanin/alum and Nippostrongylus brasiliensis infection compared with that in parental or littermate controls. The founder line exhibiting the highest level of suppression also was less susceptible to Ag-induced systemic anaphylactic shock. Overall, the data support the concept that enhancing CD23 levels can be used to suppress IgE-mediated disease. The mechanism involves decreased IgE synthesis, because the serum half-life of IgE was not altered in transgenics, and enzyme-linked immunospot analysis demonstrated lower IgE-producing cells stimulated by injection of anti-IgD. Transgenics also exhibited significantly decreased IgG1 responses and exhibited lower levels of all Ig isotypes, although this was more variable in different founder lines.

Influence of perioperative whole blood transfusions on lymphocyte subpopulations in patients with stage II breast cancer.

Preliminary reports have suggested an adverse relationship between blood transfusion and survival after surgery in patients with solid tumour. One might postulate that from these studies, perioperative blood transfusions alter host immune defences. We therefore examined the influence of homologous whole blood transfusion on circulating lymphocyte subpopulations in transfused patients compared with non-transfused patients. Fifty-one women with Stage II breast cancer who underwent surgical procedures were studied. Patients were classified into two groups on the basis of whether or not they had received blood transfusion. The lymphocyte subpopulations were analyzed by flow cytometry before cancer surgery and three weeks after the operation. CD3+, CD4+, CD8+, and CD20+ cells as the lymphocyte subsets were quantitated using appropriate monoclonal antibodies. No significant differences between pre- and postoperative lymphocyte subset levels were seen in non-transfused patients. However, there was a statistically significant increase in the CD8+ cell count; decreasing CD4+ cell count and decreased CD3+ cells levels were observed in the transfused group (P < 0.05). Although these early results of the study suggest that the blood transfusions could be associated with alterations in lymphocyte populations, additional studies are needed to elucidate the possible mechanism of the transfusion-induced immunological modulations.

Alterations of lymphocyte populations in lymph nodes but not in spleen during the latency period of adjuvant arthritis.

The aim of this study was to analyze potential imbalances in lymphocyte populations from regional lymph nodes (LN) and spleen occurring before the development of the outer inflammation of adjuvant arthritis (AA). Percentages and absolute numbers of CD5+, CD4+, CD8+, Ig+, I-A+, NKR-P1+ and TCRgammadelta+ cells were determined. No differences in percentages of gammadelta T or NK cells were found either in LN or spleen, thus ruling out an important role of these minor subpopulations in these early stages of AA. While no significant lymphocyte imbalances were observed in spleen, an increase in the percentage of B lymphocytes was found in regional LN. Moreover, a high proliferation of CD8+ cells was observed when measuring absolute numbers of LN lymphocytes, thus producing an imbalance in the CD4/CD8 ratio at very early stages of the inflammatory process. These findings suggest a role for CD8+ and B lymphocytes in the latency period of AA at the LN level. Our results indicate a primary role for lymph nodes in initiating the inflammation of AA, whereas cells from the spleen probably play a secondary role.

Alterations in the Lymphocytic and Mononuclear Phagocytic Systems of Turkey Poults Associated with Exposure to Poult Enteritis and Mortality Syndrome

In vivo and in vitro mononuclear phagocytic system functions, expression of lymphocyte subset cell surface markers in the thymus and bursa of Fabricius, and lymphocyte subset dynamics during the course of poult enteritis and mortality syndrome (PEMS) were examined. PEMS is an acute, transmissible, infectious intestinal disease accompanied by high mortality and morbidity. The etiology of this multifactorial disease remains to be elucidated; however, turkey coronavirus was initially assumed to be one of the primary agents involved. Further investigation demonstrated that turkey coronavirus was not always detectable in poults exhibiting PEMS symptoms, and, thus, PEMS poults began to be identified as positive or negative for turkey coronavirus. In each trial, uninfected hatchmate controls were compared with turkey poults that were contact exposed to PEMS poults at 7 days of age. Following intravenous inoculation, control poults cleared Escherichia coli from their circulation by 60 min, whereas viable E. coli were still present in the circulation of PEMS poults at 60 min postinoculation. Inflammatory response measured by Sephadex-elicited abdominal exudate cell recruitment and the adherence potential of abdominal exudate cells was not significantly different between uninfected and PEMS poults. The percentage of glass-adherent abdominal exudate macrophages was higher in PEMS poults. However, the ability of these macrophages to phagocytize sheep red blood cells and the average number of sheep red blood cells per phagocytic macrophage were both lower compared with uninfected controls. CD4+ expression in thymic tissue of PEMS poults at 9 days postinfection was significantly lower. The CD4+:CD8+ lymphocyte ratio in peripheral blood leukocytes from coronavirus-negative PEMS poults was lower than that from both uninfected and coronavirus-positive PEMS poults at 14 days postinfection. In the spleen, the CD4+:CD8+ lymphocyte ratio was higher in coronavirus-positive PEMS poults as compared with the other treatments. In conclusion, immune system dysfunction in PEMS is associated with impaired mononuclear phagocytic system function and alterations in lymphocyte populations.

The effect of total lymphoid irradiation and low-dose steroids on T lymphocyte populations in multiple sclerosis: correlation with clinical and MRI status

We have monitored the cell surface phenotypic changes occurring in T, B and NK cells of chronic progressive multiple sclerosis (MS) patients after total lymphoid irradiation (TLI) plus low-dose prednisone (TLI-LDP) therapy in comparison to sham TLI-LDP. TLI-LDP resulted in a marked reduction in the relative and absolute number of total CD3 + T cells, CD4 + helper T cells, CD4 +CD45RA + naive T cells and CD19 + B cells for at least 1 year after treatment. No change occurred in the percent CD8 + T cells although the number of these cells declined after radiotherapy. The CD4/CD8 T cell ratio was also decreased. The relative percent of CD16 + NK cells increased steadily after TLI-LDP while the number of NK cells transiently declined but returned to baseline values 1 year later. An increase in the percent of CD2 +CD3 − cells and a decrease in their number after therapy was also observed. In contrast, no significant changes in the number of T, B or NK cells were seen in the MS patients receiving sham TLI-LDP. These results provide further evidence that radiotherapy causes a reduction of immunocompetent T and B cells and that a population of possibly NK cells and/or immature T cells appears to be repopulating the circulation after TLI. In addition, a correlation was observed between alterations in lymphocyte populations and the presence or absence of contrast enhancing or new T 2 lesions on brain magnetic resonance imaging (MRI) in the TLI-LDP treated MS patients. Patients devoid of contrast enhancing or new T 2 lesions had a decreased percentage of CD3 + and CD4 + T cells prior to therapy and at six months following TLI-LDP compared to patients with such lesions. An association was also observed between stability in disease activity as determined on the Expanded Disability Status Scale and relative values of CD3 + T cells.

Alterations in Blood Leukocyte Populations in Smyth Line Chickens with Autoimmune Vitiligo

Smyth line (SL) chickens spontaneously develop a posthatch autoimmune loss of pigment cells (vitiligo) in the feather. Concurrent with the development of Smyth line vitiligo (SLV), mononuclear cell infiltration and altered T cell profiles can be observed in the pulp of developing feathers.To determine whether the development of SLV is preceded by or associated with alterations in blood lymphocyte and leukocyte populations, blood leukocyte profiles were established at various times prior to and throughout the spontaneous development of SLV. The proportions among various blood leukocyte populations (percentage of lymphocytes, monocytes, heterophils, eosinophils, and basophils) were determined by differential leukocyte counts. The proportions among blood lymphocyte populations were examined by immunofluorescence and flow cytometric analyses. Lymphocyte markers included fluorescence-conjugated monoclonal antibodies to identify T cells (CD3), T helper cells (CD4), cytotoxic T cells (CD8), and B cells (IgM).The proportions among blood lymphocyte populations examined did not differ between SL and MHC-matched parental Brown line (BL) control chickens prior to and throughout the development of SLV. Compared to BL controls, SL chickens had, however, increased proportions of inflammatory leukocytes in the blood, particularly at the time when most hatchmates developed SLV. Examination of leukocyte alterations with respect to first observation of SLV revealed that inflammatory leukocyte levels were elevated early in SLV.Although altered leukocyte profiles in the blood were observed during the development of SLV, blood from SL chickens did not reflect alterations in lymphocyte populations known to occur at the site of melanocyte destruction. The role of inflammatory blood leukocytes in the development of SLV needs to be further investigated.

Alterations of lymphocyte populations during development in the spontaneously hypertensive rat

Immune system abnormalities have been linked to hypertension in the spontaneously hypertensive rat (SHR). The goal of our study was to examine different lymphocyte subpopulations in the prehypertensive and developmental phases of hypertension in the SHR. Blood samples were obtained from SHR and Wistar-Kyoto (WKY) rats at the following time-points: 2 weeks and 1, 2, 3 and 4 months. Lymphocytes were separated from the whole blood. Monoclonal antibodies were used to fluorescently label the following lymphocyte subpopulations; total T cells, T non-helper cells, T helper cells and B cells. Fluorescence-activated cell sorting (FACS) analysis was used to quantify the percentages of the different subpopulations examined. The T non-helper cell population was depressed in SHR from 2 weeks of age. This finding persisted throughout the entire 4-month study period. At the 4-month time-point, the total T cell percentage was also depressed in the SHR. These results demonstrate that immune system abnormalities are present in the prehypertensive and developmental phases of hypertension in the SHR. This supports the hypothesis that the immune system is involved in the development and maintenance of hypertension in the SHR, preceding not adapting to this state.

Prevention of alterations in postoperative lymphocyte subpopulations by cimetidine and ibuprofen

Surgical procedures probably result in a temporary state of immunosuppression. Identification of functional lymphocyte subclasses using appropriate monoclonal antibodies appears to serve as a sensitive, accurate, and reproducible measure of immune status in patients in many disease states. Using monoclonal antibodies specific for lymphocyte surface markers and immunofluorescent assay, we quantitated lymphocyte subpopulations in patients undergoing surgical procedures. Cholecystectomy, colon surgery, and coronary bypass procedures all resulted in postoperative decreases in helper and inducer populations and increases in cytotoxic suppressor populations, with resultant depressions in the helper to suppressor lymphocyte ratio. Studies in an additional group of patients who underwent cholecystectomy demonstrated that these changes could be prevented by perioperative administration of ibuprofen and cimetidine. These results suggest that prostaglandins and histamines are involved in immunoregulatory events after major operation. The ability of specific pharmacologic therapy to prevent alterations in lymphocyte populations suggests that postoperative immunity may be preserved, hopefully leading to greater host resistance against infection and tumor dissemination.

Alterations in Lymphocyte Populations in Tumorigenesis

Abstract Studies have been conducted of the migration of 51Cr-labeled lymph node cells into the lymphoid tissues of mice inoculated with the Moloney sarcoma virus. Significant numbers of labeled cells were trapped in the draining lymph nodes and spleens of tumor-bearing mice. The kinetics of lymphocyte trapping correlated with the cycle of growth and spontaneous regression which is characteristic of this tumor in healthy mice. Trapping first occurred after injection of the virus and maximal retention of lymphocytes corresponded to the time of tumor regression.