Phenotypic changes of T-lymphocyte subsets induced by interleukin-12 and interleukin-15 in umbilical cord vs. adult peripheral blood mononuclear cells

The decreased incidence of graft-vs.-host disease found following umbilical cord blood (CB) transplantation, and the increased susceptibility of newborns to infections, have been attributed, in part, to functional and phenotypic immaturity of neonatal T cells. We investigated the phenotypic changes of CB T cells induced by two immunoregulary cytokines, interleukin (IL)-12 and IL-15, alone or in combination. Adult peripheral blood (APB) mononuclear cells (MNCs) were also tested for comparison. Prior to culture, the percentages of CD3⁺ CD8⁺, CD3⁺ CD25⁺, and CD3⁺ CD56⁺ cells were significantly lower in CB MNCs than in APB MNCs. IL-15, but not IL-12, significantly increased CD3⁺ CD8⁺ expression among the CB MNCs after 1 week of culture. Combining IL-12 and IL-15, however, resulted in decreased CB CD3⁺ CD8⁺ expression compared with IL-15 alone. The percentage of CD3⁺ CD25⁺ cells in CB MNCs spontaneously increased in the absence of cytokines, while that of CD3⁺ CD56⁺ cells in CB MNCs could not be enhanced with cytokines. In contrast, the percentages of CD3⁺ CD25⁺ and CD3⁺ CD56⁺ cells among the APB MNCs could be increased with IL-12, IL-15, and further with IL-12 and IL-15 combined. Thus, different patterns of T-cell subset changes were demonstrated between CB MNCs and APB MNCs in response to IL-12 and/or IL-15. These data may serve as a foundation for using cytokine therapy in newborns and children receiving CB transplants.     

Susceptibility to Fas and tumor necrosis factor-α receptor mediated apoptosis of anti-CD3/anti-CD28-activated umbilical cord blood T cells

Decreased severity of graft-versus-host disease after mismatched umbilical cord blood (UCB) transplantation may be attributed in part to the increased propensity to apoptosis of UCB T cells following activation. Interleukin (IL)-15, a pleiotropic cytokine that is essential for T-cell proliferation and survival, may serve as promising immunomodulative therapy post-CB transplantation for its anti-apoptotic effect. This study aimed to determine the kinetics of Fas or tumor necrosis factor-α receptor (TNFR) mediated caspase-3 expression and apoptosis of anti-CD3/anti-CD28 activated UCB T cells in the influence of IL-15. Activated caspase-3 expression was analyzed by Western blotting and the percentage of apoptotic cells was determined by annexin-V/propidium iodide (PI) flow cytometric staining. Significant expression of Fas and TNFR2 was detected on anti-CD3/anti-CD28 pre-activated UCB T cells. These cells were susceptible to anti-Fas but not TNF-α-induced apoptosis. Kinetic study shows that caspase-3 expression became evident at 6th–8th h following anti-Fas stimulation, while early apoptotic cells with annexin-V⁺/PI⁻ expression appeared at 12th–16th h. IL-15, though successful in decreasing apoptosis in pre-activated UCB T cells, failed to completely prevent Fas-mediated caspase-3 expression and apoptosis of CB T cells. The pre-activated UCB and adult peripheral blood T cells behaved similarly with regard to death receptor expression, caspase-3 expression and apoptosis upon Fas-engagement. Although IL-15 promotes overall activated UCB T-cell survival, it did not particularly prevent Fas-mediated activation-induced cell death.     

Case report of common variable immunodeficiency with functional T-helper defect and reduced CD4+ LAM−1 T cells

A 10 year-old boy presenting with an empyema and a previous medical history of recurrent and disseminated infections was investigated immunologically. The serum immunoelectrophoresis showed hypogammaglobulinaemia. The in vitro lymphocyte proliferation to T-cell mitogens (PHA and Con A) was diminished and the response to a T-dependent B cell mitogen (PWM) was severely diminished. Phenotypic analysis of his lymphocytes with monoclonal antibodies revealed normal CD3⁺, CD4⁺ and CD8⁺ cells with a normal CD4: CD8 ratio. Double immunofluorescence with Leu 8 antibody revealed a selective deficiency of the CD4⁺ LAM 1⁻ subset. Co-culture experiments between patient's B cells and supernatants from normal T cells showed that the patient's B cells could secrete Ig in vitro. We suggest that the Leu 8 monoclonal antibody may be useful in defining abnormalities in the regulatory subsets of T lymphocytes and that these abnormalities may be relevant in the pathogenesis of common variable immunodeficiency.     

Decreases in circulating CD4+CD25hiFOXP3+ cells and increases in intragraft FOXP3+ cells accompany allograft rejection in pediatric liver allograft recipients

Abstract:  We examined CD4⁺CD25^hiFOXP3⁺ cells Treg in children following liver transplantation and determined the relationship between Treg cell levels in the blood and in the graft. Peripheral blood was obtained from pediatric liver transplant patients at sequential time points: pre-transplant, one month, 3–4 months, 6–7 months, and 11–12 months post-transplant. PBMC were isolated, labeled for CD4, CD25 and FOXP3 expression and analyzed by flow cytometry for CD4⁺CD25^hiFOXP3⁺ cells. Sorted CD4⁺CD25^hi cells were assessed for functional activity. Pretransplant blood levels of CD4⁺CD25^hiFOXP3⁺ Treg cells were not significantly different from post-transplant blood levels of CD4⁺CD25^hiFOXP3⁺ Treg cells. However, the blood levels of CD4⁺CD25^hiFOXP3⁺ Treg cells were significantly decreased during acute rejection compared with levels when graft function was stable. Immunohistochemistry revealed that FOXP3⁺ cells were increased in the portal region of livers with histopathologic evidence of acute graft rejection compared with livers without evidence of rejection and were localized primarily within the inflammatory infiltrate. These data indicate that Treg cells are found at the site of allograft rejection and may play a role in regulation of alloreactivity. Moreover, monitoring peripheral CD4⁺CD25^hiFOXP3⁺ Treg cell levels may be useful in improving the post-transplant management of pediatric liver allograft recipients.     

Both allergen-specific CD4 and CD8 Type 2 T cells decreased in asthmatic children with immunotherapy

Allergen-specific immunotherapy (IT) has been used for the treatment of atopic diseases since the turn of this century. The precise working mechanisms, however, remain to be clarified. The aim of this study was to investigate the role of particular subsets of allergen-specific T cells in the non-atopic individuals, untreated asthmatic children and the asthmatic children receiving immunotherapy. We collected peripheral blood from 16 untreated asthmatic children and 17 asthmatic children receiving immunotherapy over one and half years. All the patients were sensitive to mite allergen. Peripheral blood mononuclear cells (PBMC) were isolated and, in vitro , stimulated with crude mite extract to enrich the mite-specific T-cell population. After 14 days, the enriched mite-specific T cells were stimulated with phorbol-12-myristate-13-acetate (PMA) and ionomycin for intracellular detection of cytokines such as IFN-γ, IL-4 in CD4⁺ and CD8⁺ T lymphocytes. The data here demonstrated that the levels of mite-specific IgG4 and IgA increased significantly in asthmatic children after immunotherapy. In addition, both IL-4 expressing CD4⁺ and CD8⁺ T cells were significantly lower in asthmatic children after immunotherapy compared with those of before treatment and the normal control (p < 0.05). In contrast, the frequency of IFN-γ expressing CD4⁺ and CD8⁺ T cells did not significantly differ between untreated and SIT-treated groups. All these data suggested that decreased Type 2 CD4⁺ and CD8⁺ T cells might be closely correlated with the regulatory mechanisms of immunotherapy.     

Expression of chemokine receptor CX3CR1 in infants with respiratory syncytial virus bronchiolitis

Respiratory syncytial virus (RSV) glycoprotein G mimics fractalkine, a CX₃C chemokine, which mediates chemotaxis of leukocytes expressing its receptor, CX₃CR1. The aim of this study was to examine the relationship between RSV infection and expression of perforin and IFN- γ in CX₃CR1-expressing peripheral blood CD8⁺ T cells. Samples were collected from infants with RSV bronchiolitis, both in the acute and convalescence phase (n = 12), and from their age- and sex-matched healthy controls (n = 15). Perforin expression and IFN- γ secretion in CX₃CR1⁺ CD8⁺ T cells were assessed by four-color flow cytometry. The NF- κ B p50 and p65 subunit levels were also determined as markers of RSV-induced inflammation. Study results showed perforin and CX₃CR1 expression to be significantly lower in the convalescent phase of infected infants than in healthy controls. There was no significant difference in IFN- γ secretion and NF- κ B binding activity between two time-points in RSV-infected infants, or when compared with healthy controls. Infants with prolonged wheezing had lower acute-phase CX₃CR1 levels in peripheral blood. These data indicate existence of an event persisting after acute RSV infection that is able to modulate effector functions of cytotoxic T cells, and also link disease severity with CX₃CR1 expression.     

T Cell Activation and T Cell Receptor Variable Region Gene Usage in Measles

T cell activation and T cell receptor variable (V) regions were studied with monoclonal antibodies in peripheral blood lymphocytes from 22 patients with measles. Increased (> 5%) activated T cells (HLA-DR⁺ CD3⁺ cells) were noted in 14 of the 22 patients. Elevations of Vβ5⁺ and Vβ8 + T cells were observed in two and four patients, respectively, and appeared to be associated with T cell activation. The duration of fever was significantly prolonged in those with increased (> 10%) activated T cells (p < 0.01). These results suggest that T cell activation and the preferential expansion of Vβ8⁺ and Vβ5⁺ T cells are associated with the pathogenic process of measles.     

Mucosal T cells recovered from mice after infection with respiratory syncytial virus display a memory/activation phenotype

Pgp-1 expression was studied as a marker of memory/activation on systemic and mucosal T cells of BALB/c and C57BL/6 mice after infection with respiratory syncytial virus (RSV), using two-color dual fluorescence flow cytometry employing anti-L3T4 (CD4), anti-Ly2 (CD8), and anti-Pgp-1 (CD44) monoclonal antibodies. Pgp-1 was expressed in relatively low densities on T cells of C57BL/6 mice, allowing differentiation of a dual population of Pgp-1¹⁰ and Pgp-1^hi T cells after antigenic stimulation in vivo. On the contrary, T cells of BALB/c mice were uniformely Pgp-1^hi, making this mouse strain less suitable for studies with this marker. In blood and spleen consistently more CD8⁺ than CD4⁺ T cells were Pgp-1^hi, while in BAL more CD4⁺ than CD8⁺ T cells were Pgp-1^hiAfter primary but not after secondary infection, CD4⁺ Pgp-1^hi T cells increased significantly in the blood and spleen. After secondary infection both CD4⁺ Pgp-1^hi and CD8⁺ Pgp-1^hi T cells increased in the BAL. It is hypothesized that after primary infection systemic RSV-specific T cells acquire an activation/memory phenotype as characterized by an enhanced expression of Pgp-1, resulting in a faster and stronger influx of these cells in the lungs after secondary infection.     

Lymphocyte subsets and cytokines in adenoviral infection in children

To determine the distribution of major blood lymphocyte subsets we evaluated blood lymphocytes by flow cytometry in adenovirus-infected infants aged 30–730 d. In addition, interleukin-1-receptor antagonist, interleukin-10 and transforming growth factor-β1 were measured in serum by enzyme-linked immunosorbent assay. According to clinical parameters, mechanical ventilation and outcome, infections were classified as moderate ( n = 15), severe ( n = 11) and fatal ( n = 12). Controls were 13 healthy children. In severe and fatal infection, T cells (CD5⁺/CD19^-), NK effectors (CD16⁺), CD4⁺ T subset and B1 subset of B lymphocytes (CD5⁺/CD19⁺) were all significantly decreased. CD8⁺ cells were decreased in severe but not fatal cases. There was no difference in serum values of interleukin-10; however, fatal cases had high interleukin 1-receptor antagonist values. Interestingly, patients with moderate infection showed significantly increased values of transforming growth factor-β1. These results demonstrate that life-threatening adenoviral infection is associated with marked abnormalities in blood lymphocyte and cytokine profile.     

Regulation of CD31 expression and interleukin-4 production by human cord blood CD4+ T cells with interleukin-4 and interleukin-7

BACKGROUND: T helper 2 cell type cytokines, such as interleukin (IL)-4 and IL-5, play pivotal roles in the development of allergic diseases. However, the mechanism by which naive CD4+ T cells acquire the ability to produce these cytokines remains unclear. Recently, it was reported that IL-7 induces the ability to produce IL-4 as well as interferon (IFN)-gamma and IL-5 in naive CD4+ T cells without TCR stimulation. To further analyze the mechanism of acquiring IL-4-producing ability by naive CD4+ T cells, the effects of IL-7 on human cord blood CD4+ T cells were compared with those of IL-4, which induced the ability to produce IFN-gamma but not IL-4. RESULTS: Interleukin-7 preserved the population of CD4+CD31- T cells in cord blood and induced their IL-4-producing ability without T cell receptor (TCR) stimulation, while IL-4 induced CD31 on CD31- T cells and could not induce their IL-4-producing ability. Both the CD31-inducing effect and the inhibitory priming effect for IL-4-production by IL-4 were also observed after cord blood CD4+ T cells had been primed with IL-7 and acquired the IL-4-producing ability. CONCLUSIONS: Interleukin-7 induced the IL-4-producing ability in naive CD4+CD31- T cells without TCR stimulation, suggesting that the signal transduction via CD31 may have an inhibitory effect on the acquisition of the IL-4-producing ability by cord blood CD4+ T cells in the absence of TCR stimulation.     

Unrelated cord blood transplantation in children with severe congenital neutropenia

Abstract:  SCN is an inherited hematological disorder with severe neutropenia and recurrent infections. Although there are some reports that recombinant rhG-CSF improves clinical outcome, allogeneic HSCT appears to be the only curative treatment for these patients. We report here two children with SCN successfully treated by CBT from unrelated donors. They were refractory to rhG-CSF treatment and have no identical family donor. Bu + CY were given as conditioning. Case 1 and Case 2 received 6/6 and 5/6 HLA-matched unrelated umbilical cord blood, respectively. The number of infused nucleated cells was 6, 18 × 10⁷/kg and CD34⁺  cell number was 3, 74 × 10⁵/kg in Case 1. Those cell numbers were 8, 8 × 10⁷/kg and 5, 34 × 10⁵/kg for Case 2, respectively. Neutrophil/platelet engraftments were 45/49 days in Case 1 and 24/36 days in Case 2. Grade II cutaneous acute GVHD was seen in Case 2 that was treated successfully with prednisolone. Both patients are well with normal hematological findings and full donor chimerism for post-transplant 20 and 24 months, respectively. We conclude that UCB can be considered as a safe source of stem cell in patients with SCN who need urgent HSCT.     

Two year follow-up of immunological response in mite-allergic children treated with sublingual immunotherapy. Comparison with subcutaneous administration

Although the efficacy of allergen-specific sublingual immunotherapy (SLIT) is now accepted, the underlying mechanisms remain elusive. Such mechanisms are better documented in the case of subcutaneous immunotherapy (SCIT). In order to understand the T-lymphocyte response in patients receiving SLIT, we compared children with respiratory disease monosensitized to Dermatophagoides pteronyssinus receiving SLIT or SCIT over a 2-yr period. Peripheral blood was obtained before beginning immunotherapy, and after 3 months, 1 yr and 2 yr. Total IgE, specific IgE and IgG4 to D. pteronyssinus were determined in serum. T-cell markers (CD3, CD4, CD8, CD25) and intracellular cytokine production (TNF- α , IL-2, IL-4 and IFN- γ ) were determined in peripheral blood mononuclear cells (PBMC) by flow cytometry. No differences between SCIT and SLIT were detected in the clinical variables or in the subjective evaluation. Although an increase in specific IgE and IgG4 was only detected in SCIT, a significant decrease in the specific IgE/IgG4 ratio was found in both groups. SCIT and SLIT experienced an increase in the CD4/CD8 ratio over time, but an increase in the CD4⁺CD25⁺ and a decrease in the CD8⁺CD25⁺ subsets were only found with SCIT. A slight shift from a Th2 to a Th1 pattern, measured by the IFN- γ /IL-4 ratio, was only detected in the CD4 T cells with SCIT. A decrease in both groups was found in TNF- α and IL-2 production over time. Children with respiratory allergic diseases receiving SCIT or SLIT had a different immunologic response in peripheral blood during treatment, though the clinical improvement was similar. Whether SLIT induces a mucosal protective response should be studied.     

Interleukin-15 enhances CD4+ CD45RA+ expression on umbilical cord blood mononuclear cells

The reduced incidence of graft‐vs.‐host disease following umbilical cord blood (CB) transplantation may be related to the functional immaturity of newborn T cells expressing mainly the naive CD45RA phenotype. Expansion of CD4⁺ CD45RA⁺ T cells using cytokines may benefit neonates and infants with human immunodeficiency virus (HIV) infection, as a preferential decline in CD4⁺ CD45RA⁺ cells has been noted as HIV disease progresses. The aim of the study was to investigate the effect of interleukin (IL)‐15, a novel cytokine similar to IL‐2 in biological activities, on CD45RA/RO expression and apoptosis in umbilical cord blood (CB) and adult peripheral blood (APB) mononuclear cells (MNCs). Prior to culture, CB MNCs contained a greater number of CD4⁺ CD45RA⁺ cells and fewer CD4⁺ CD45RO⁺ cells than did APB MNCs. When incubated with RPMI‐1640 containing 10% fetal calf serum for 7 days, the percentage of CD45RA⁺ cells within CD4⁺ T cells (%CD45RA⁺/CD4⁺) significantly decreased compared to that of fresh CB MNCs. IL‐15 exerted a dose‐dependent increase of %CD45RA⁺/CD4⁺ and a corresponding decrease of %CD45RO⁺/CD4⁺ in CB MNCs, an effect not observed with APB MNCs treated with IL‐15. The percentages of CD45RA⁺ and CD45RO⁺ expression within CD8⁺ cells, however, were not influenced by IL‐15, in either CB or APB MNCs. A greater number of CB MNCs underwent apoptosis than did APB MNCs after 7 days of culture in RPMI‐1640 containing 10% fetal calf serum. IL‐15 did not inhibit apoptosis but induced proliferation comparable to that achieved in APB MNCs. The ability of IL‐15 to preferentially enhance the proliferation of CD4⁺ CD45RA⁺ cells in CB MNCs suggests a role for immunomodulative therapy in HIV‐infected newborns and infants.     

15N Tracer Investigations of the Physiological Availability of Urea Nitrogen in Mother's Milk

ABSTRACT. The physiological availability of urea in mother's milk was investigated in tracer studies using [¹⁵N]₂ urea and involving 22 infants. The incorporation of ¹⁵N into the body protein was established in 16 subjects by emission spectrophotometrical determination of the ¹⁵N excess in the serum protein. Between 2 % and 3.6 % of the serum protein is synthesized from the urea nitrogen in mother's milk. In further studies on the ¹⁵N balance in 6 infants, renal excretion of ¹⁵N after oral multiple and single impulse labelling with [¹⁵N]₂ urea constituted 60 % of the dose administered. Three-tenths –2.5 % was excreted in the feces. The retention of ¹⁵N in the protein pool varied between 16.7 and 61.4 %     

Transforming growth factor-β1 is elevated in unpasteurized cow's milk

Unpasteurized milk consumption was associated with less atopy prevalence. Not only microbial load but also fatty acids and cytokines such as transforming growth factor-β₁ (TGF-β₁) may play a role on the effect of unpasteurized milk. Levels of TGF-β₁ in different cow's milk samples were evaluated: we consider raw unpasteurized milk before and after boiling, commercial pasteurized and micro-filtrated cow's milk and different commercially available cow's milk formulas. TGF-β₁ concentration in raw unpasteurized cow's milk was 642.0 ± 52.9 pg/ml before boiling and decreased significantly after boiling (302.7 ± 50.59 pg/ml) (p < 0.05). TGF-β₁ concentrations were also significantly lower in commercial pasteurized milk (246.2 ± 43.15 pg/ml) and in commercial micro-filtrated milk (213.0 ± 31.6 pg/ml) in comparison to unpasteurized unboiled milk (p = 0.002). The levels of TGF-β₁ in all formula samples were below the threshold of detectability for the assays. As TGF-β₁ in the milk may contribute to the development of the immature gastrointestinal tract by influencing IgA production and oral tolerance induction, we suggest to consider not only the microbial compounds but also the cytokine patterns to explain the protective effect of unpasteurized cow's milk on allergic disorders.     

Low-dose cyclosporin A microemulsion in children with severe atopic dermatitis: Clinical and immunological effects

Cyclosporin A (CsA) is an effective and well-tolerated treatment for severe childhood atopic dermatitis (AD). By starting at a low dose, the therapeutic safety should be further increased. The aim of this study was to evaluate low-dose CsA in childhood AD with respect to clinical outcome and modulation of T-cell dysregulation. In an open prospective study, 10 children (age: 22–106 months) with severe AD (mean objective SCORAD score > 40 on two baseline measurements at a minimum interval of 2 weeks) were treated with CsA solution for 8 weeks. All patients received a starting dose of 2.5 mg/kg/day, which was increased stepwise in non-responders to a maximum of dose of 5 mg/kg/day. Disease activity was monitored using the SCORAD index. The frequency of cytokine-producing peripheral blood T lymphocytes was analyzed by intracellular cytokine staining, and T-cell numbers were measured by fluorescence-activated cell sorter (FACS) analysis. Twenty healthy age-matched children were included as controls for the immunological data. Nine of the 10 patients had a SCORAD reduction of at least 35%. In seven patients this was achieved with low-dose CsA at 2.5 mg/kg/day (n = 4) and 3.5 mg kg/day (n = 3). Seven of the nine responders experienced no relapse within the 4-week follow-up period. At baseline the percentage of interleukin-4 (IL-4), IL-13, and human leucocyte antigen (HLA)-DR-positive CD3⁺ cells was higher in the patient group than in the controls. After CsA treatment there was a significant reduction in interferon-γ (IFN-γ), IL-2, IL-4, IL-13, and HLA-DR-positive CD3⁺ cells. Hence, in severe pediatric AD, CsA microemulsion, when started at a low dose (2.5 mg/kg/day), improves clinical measures of disease, reduces T-lymphocyte cytokine production, and regulates T-cell activation.     

INCREASED FRACTIONAL EXCRETION OF PHOSPHATE AND BETA2-MICROGLOBULIN IN UNILATERAL RENAL DISEASE

ABSTRACT. Following progressive nephron loss tubular reabsorption in the remaining nephrons will fall to preserve solute and electrolyte excretion. We have examined the fractional excretion (FE) of phosphate, sodium, beta₂-microglobulin (β²M)and tubular glucose reabsorption (T_glucose) in children with unilateral renal disease to find 1) the threshold for this response and 2) whether intrinsic renal mechanisms can elicit this response. Separate renal function studies were performed using unilateral ureteral compression. Total glomerular filtration rate (GFR) was 93.7 ± 2.99 ml/1.73(m²)^-1.min^-1, and 110.25 ± 5.40 in control children. GFR in the scarred kidney (SK) was 22.4 ± 2.46 and in the contralateral kidney (CIK) 67.2 ± 4.60 ml. 1.73 (m²)^-1. min^-1. The kidney area was reduced in proportion to GFR in SK. FE phosphate and β₂M were significantly higher in SK than in CIK (sign test), but absolute values for FE_phosphate and β₂M were not higher in SK than in control kidneys. FE_sodium and T_glucose were the same in SK and CIK. Conclusion: Following moderate unilateral reduction of GFR selective depression of tubular reabsorption can occur without extrarenal impulses.     

Phenotypes of Peripheral Blood Lymphocytes during Acute Hepatitis A

ABSTRACT. We investigated peripheral blood lymphocyte phenotypes of 74 patients at weekly intervals during the course of acute hepatitis A. In the second week after onset of jaundice, a significant elevation of total lymphocytes was observed (4096 × 10⁶± 1003 × 10⁶/l vs. controls 3038 × 10⁶± 1208 × 10⁶/l, p < 0.005). However, no change in the relative percentages of B-cells (CD20+), T-cells (CD3+ or CD2+), or T-cell subpopulations (CD4+ helper cells and CD8+ suppressor cells) could be demonstrated during the course of the disease. Activated T-cells (CD3+DR+) were elevated during the first week (204 × 10⁶± 134 × 10⁶/l vs. normal 91 × 10⁶± 54 × 10⁶/l, p <0.005) and during the second week (202 × 10⁶± 82 × 10⁶/l, p < 0.0005) after onset of disease and returned to normal values until the third week. Cells expressing phenotypes of lymphocytes capable of exerting non-MHC-restricted cellular cytotoxicity, i.e. Natural Killer cell activity (CD57+, CD16+, and CD56+) were significantly elevated in percentage in the first week of disease, as compared to controls (CD57: 14.5 ± 7.0% vs. 9.3 ± 5.8%, p <0.05; CD16: 13.4 ± 7.3 vs. 9.5 ± 5.1%, p < 0.05; CD56: 10.5 ± 3.5% vs. 8.0 ± 1.5%, p < 0.005). Also the absolute numbers of these lymphocyte subpopulations were found to be elevated during the first and second week. The increase in NK cells in the initial phase of acute hepatitis A suggests an important role of these cells in the first line of defence in this disease.     

Altered T lymphocyte phenotype at birth in babies born to atopic parents

Flow cytometry was used to analyse the cord blood T cells of 33 babies at high risk 'HR' for developing allergy (born to at least one atopic, asthmatic parent), and 10 low risk 'LR' babies (born to non-atopic parents), following normal term deliveries. Significantly lower numbers of CD25⁺, (activated) T cells (p<0.005) were seen in the cord blood of the HR babies who had developed both allergic symptoms and positive skin prick tests by one year of age when compared with the LR group. CD45RO⁺ (memory) T cells were detected in both HR and LR babies with a trend for lower numbers of memory cells to be detected in HR infants who later developed allergic symptoms and/or positive skin prick tests. Significantly lower numbers of CD4⁺/CD45RO⁺ were seen in the cord blood of HR babies who developed allergic symptoms compared to HR babies who showed no sign of allergy by one year and to the LR babies (p<0.05 and p<0.005). The presence of activated and memory T cells at birth implies intra-uterine priming. The significantly lower numbers of memory T cells in the HR babies suggests a suppression of T cell activation or lack of antigenic priming in this group. This prenatal influence on babies born to atopic parents may have important implications with regard to the mechanisms underlying atopic sensitisation.     

Increased Ig-null B lymphocytes in the peripheral blood of pediatric solid organ transplant recipients with elevated Epstein-Barr viral loads

Abstract:  In this study, the characteristics of Ig-null B cells in high viral load carriers were examined by four-color flow cytometry. The frequency of Ig-null B cells in patients with high, low or undetectable virus loads was found that while patients with a high load had more Ig-null cells, these cells were also present in the low and undetectable load groups. As Ig-null cells from patients with no viral load were EBV-negative, EBV infection was not absolutely required for the generation or survival of Ig-null cells. Ig-null cells were CD19⁺, sIg^-, CD5⁻, CD10⁻, CD27⁻, CD23⁻, CD38⁻, and CD69⁻ with variable surface expression of CD20 and CD40. Ig-null cells did not have a proliferating cell phenotype (Ki67^-) and a high proportion were HLA class I^- and class II^-. Virus copy number in CD19⁺ Ig-null cell populations may be much higher than in CD19⁺ Ig⁺ cell populations. EBV infected Ig-null cells were common in blood specimens from pediatric solid organ transplant recipients and infected Ig-null cells may pose potential problems for immunotherapies that target infected B cells directly.