Thomas Böhler

Deformability and volume of neonatal and adult leukocytes.

ABSTRACT: Volume and deformability of blood cells are important determinants of the microcirculation. Leukocytes are larger and considerably less deformable than erythrocytes. In our study, volume and deformability of polymorphonuclear neutrophils (PMN), lymphocytes, and monocytes in adults and full-term neonates were studied by means of a micropipette system. Neonatal immature granulocytes were also investigated. Membrane cytoplasm tongues were aspirated into 2.5-μm (diameter) micropipettes over a period of 1 min. Adult and neonatal PMN were totally aspirated into 5-μm micropipettes. Tongue growth and final tongue length of PMN were about twice those of monocytes and lymphocytes. At a pressure of −2 cm H2O, tongue growth of lymphocytes and monocytes was similar. At a pressure of −4 cm 2O, however, tongue growth of monocytes was faster and the final tongue was longer than those of lymphocytes (p < 0.05). Cellular volume and deformation behavior of the different leukocyte subpopulations (PMN, monocytes, and lymphocytes) were similar in neonates and adults. Compared to mature neonatal PMN, immature neonatal neutrophilic granulocytes were significantly less deformable (final tongue length of 5.4 ± 1.52 versus 9.3 ± 1.48 pm at −2 cm H2O) and larger (421 ± 68 versus 360 ± 38 fL). The entry time of PMN into 5-pm micropipettes was similar in neonates and adults at aspiration pressures of −2, −3, and −4 cm H2O. We conclude that the deformability of neonatal and adult leukocytes is not different despite functional differences and that immature granulocytes may contribute to impaired microcirculation in neonates with severe septicemia or hypoxemia.

Immunohematological Reference Values for Healthy Adults in Burkina Faso

ABSTRACT Reference ranges for peripheral blood lymphocyte subsets were generated for 186 healthy adults in Burkina Faso using single-platform flow cytometry. CD4+ T-cell counts ranged from 631 to 1,696 cells μl−1; they were lower in males (n = 97) than in females (n = 89), whereas natural killer cell counts were higher.

Anti-CD95 (APO-1/Fas) autoantibodies and T cell depletion in human immunodeficiency virus type 1 (HIV-1)-infected children.

Advanced stages of HIV-1-infection are characterized by progressive CD4+ T cell depletion. Peripheral T cells from HIV-1+ donors show accelerated apoptosis in vitro. The CD95 (APO-1/Fas) receptor/ligand system is involved in this process. To further study deregulation of the CD95 system in peripheral T cells during HIV-1-infection, we measured CD95-expression on CD4+ and CD8+ T cells together with serum levels of soluble CD95 (sCD95) and anti-CD95 autoantibodies in HIV-1+ children and healthy controls. Anti-CD95 levels in HIV-1+ children were significantly elevated when compared to uninfected controls, whereas serum levels of sCD95 were not different. In HIV-1+ children, CD95-expression on CD4+ and CD8+ T cells increased with age. A strong correlation between depletion of CD4+ cells in vivo and increase in CD95-expression on CD4+ T cells was observed. In contrast, such a correlation was not found for CD8+ T cells. A negative correlation between anti-CD95 autoantibody levels and CD4+ T cell counts, that was predicted by multiple linear regression analysis of pooled data, was found in individual patients observed longitudinally by repeated measurements. Since anti-CD95 autoantibodies isolated from HIV-infected adults have previously been shown to induce apoptosis of sensitive target cells in vitro, we speculate that the interaction of these antibodes with CD95-positive and CD95-sensitive T cells in vivo might be involved in progressive T cell loss during HIV-1-infection.

Breast milk as the “water that supports and preserves life”—Socio-cultural constructions of breastfeeding and their implications for the prevention of mother to child transmission of HIV in sub-Saharan Africa

OBJECTIVES Complementary breastfeeding represents an important source of risk of HIV infection for infants born to HIV positive mothers. The World Health Organisation recommends that infants born to HIV positive mothers receive either replacement feeding or exclusive breastfeeding (EBF) followed by early weaning. Beyond the clinical and epidemiological debate, it remains unclear how acceptable and feasible the two options are for rural populations in sub-Saharan Africa. This qualitative study aims to fill this gap in knowledge by exploring both the socio-cultural construction and the practice of breastfeeding in the Nouna Health District, rural Burkina Faso. METHODS Information was collected through 32 individual interviews and 3 focus group discussions with women of all ages, and 6 interviews with local guérisseurs. RESULTS The findings highlight that breastfeeding is perceived as central to motherhood, but that women practice complementary, rather than exclusive, breastfeeding. The findings also indicate that women recognise both the nutritional value of breast milk and its potential to act as a source of disease transmission. CONCLUSIONS The findings suggest that given the socio-cultural importance attributed to breastfeeding and the prevailing poverty, it may be more acceptable and more feasible to promote EBF followed by early weaning than replacement feeding. A set of operational strategies are proposed to favour the prevention of mother to child transmission of HIV in the respect of the local socio-cultural setting.

Mechanical Fragility of Erythrocyte Membrane in Neonates and Adults

ABSTRACT: The shortened life span of neonatal red blood cells (RBC) is associated with accelerated membrane loss. The present study was designed to measure the critical shear force that causes membrane failure and the rate of membrane failure for neonatal and adult RBC. A micropipette technique was used to determine the membrane extensional (shear) elastic modulus (i.e. resistance of the membrane to extensional elastic deformation), the rate of extensional membrane deformation (i.e. surface viscosity), and the tension for local membrane fragmentation. A flow channel system was used to determine the critical shear force of plastic membrane deformation (i.e. beginning of membrane tether formation), the rate of plastic deformation, and the plastic shear viscosity coefficient. The extensional elastic modulus of neonatal RBC was 18% smaller and the rate of elastic deformation was 25% longer compared with adult cells (p < 0.05). Membrane surface viscosity was similar for both cell types. The tension for local membrane fragmentation in the micropipette was 23% lower in neonates than in adults. However, the strain (i.e. extent of membrane deformation calculated as ratio of the stress resultant and the elastic modulus) at which membrane rupture in the micropipette occurred was similar for neonatal and adult RBC. This indicates that the smaller critical tension for neonatal RBC membrane failure was due to increased membrane elastic deformability. The critical shear force for membrane tether formation in the flow channel was similar for neonatal and adult RBC (1.17 ± 0.13 vs 1.19 ± 0.21 ± 10−6 dyne, p > 0.1), whereas the tether growth was about two times faster and the plastic viscosity coefficient was 50% less for neonatal RBC compared with adult cells. These results indicate that the critical force for membrane failure is similar for neonatal and adult RBC if the increased membrane deformability of neonatal RBC is considered. However, once the membrane begins to fail, neonatal RBC appear to lose more membrane per unit time.

Revision of the diagnosis of T-zone lymphoma in the father of a patient with autoimmune lymphoproliferative syndrome type II.

Autoimmune lymphoproliferative syndrome (ALPS) is a disease of childhood characterized by typical clinical and laboratory findings. Here we describe an adult patient presenting with lymph node enlargement and splenomegaly. Pathological examination of an adenopathy supported the diagnosis of malignant T‐zone lymphoma. The patient was treated accordingly. 3 years later his child was diagnosed with ALPS. Therefore the diagnosis of the fathers disease was reconsidered. Review of the slides and functional tests led to the diagnosis of ALPS in both father and son. ALPS should be considered as a possible differential diagnosis in adult patients presenting with rare types of T‐cell lymphomas.

Effects of neuraminidase and trypsin on surface charge and aggregation of red blood cells

Trypsin and neuraminidase decrease the surface charge of red blood cells (RBC) and should, therefore, increase red cell aggregation (RCA). To assess the reliability of the Myrenne aggregometer to detect extremely strong RCA, RBC from nonnal adults were treated with neuraminidase or trypsin in vitro. RBC surface charge was estimated by partitioning of RBC in a two phase system containing dextran and polyethyleneglycol. RBC aggregation was studied by means of a Myrenne aggregometer and by microscopic observation in a rheoscope. RBC partition coefficient (i.e. surface charge) was 89% for normal RBC, 34% for trypsin and 5% for neuraminidase treated RBC. RCA in the Myrenne aggregometer increased markedly with trypsin, but tended to decrease with neuraminidase treatment. Observation of RCA in the rheoscope showed that neuraminidase caused strong RBC aggregation and that dispersion of RBC aggreg~tes was incomplete even at high shear. We conclude that studies of RCA should always include microscopic observation.

Increased energy expenditure and fecal fat excretion do not impair weight gain in small-for-gestational-age preterm infants

In order to optimize the nutrition of high-risk premature infants beyond the early postnatal period, a more precise knowledge of individual nutritional requirements is needed. We therefore studied the influence of intrauterine growth retardation on energy expenditure and nutrient utilization determined by indirect calorimetry and fecal fat excretion (steatocrit) in nineteen premature infants who were appropriate-for-gestational-age (AGA; mean gestational age 29.9+/-0.3 weeks, mean birth weight 1.30+/-0.05 kg) and thirteen small-for-gestational-age (SGA) premature infants [mean gestational age 32.4+/-0.5 weeks, mean birth weight 1.024+/-0.07 kg (i.e., below the 10th percentile)] during the first and second month of life. All infants were clinically stable during the study period. In nine SGA infants we observed a significantly higher steatocrit compared to twelve AGA infants (29+/-1 vs. 17+/-1% p = 0.0001). SGA infants (n = 12) also showed a slightly (albeit statistically not significantly) higher energy expenditure than AGA infants (n = 15) (58.7+/-1.9 vs. 53.6+/-1.5 kcal/kg per day, p = 0.054). Despite the increased fat excretion and higher energy expenditure, SGA infants gained weight more rapidly during the study period than AGA infants (20+/-1 vs. 17+/-1 g/kg per day, p = 0.026). We conclude that influences of intrauterine growth retardation on energy expenditure and nutrient utilization persist during the first weeks of extrauterine life. However, these metabolic changes do not impair the capability of SGA infants for extrauterine catch-up growth if adequate nutrition is provided.

Immune Reconstitution During the First Year of Antiretroviral Therapy of HIV-1-Infected Adults in Rural Burkina Faso

There are no data on the outcome of highly active antiretroviral therapy (HAART) in HIV-infected adults in rural Burkina Faso. We therefore assessed CD4+ T-cell counts and HIV-1 plasma viral load (VL), the proportion of naive T-cells (co-expressing CCR7 and CD45RA) and T-cell activation (expression of CD95 or CD38) in 61 previously untreated adult patients from Nouna, Burkina Faso, at baseline and 2 weeks, 1, 3, 6, 9 and 12 months after starting therapy. Median CD4+ T-cell counts increased from 174 (10th-90th percentile: 33-314) cells/µl at baseline to 300 (114- 505) cells/µl after 3 months and 360 (169-562) cells/µl after 12 months of HAART. Median VL decreased from 5.8 (4.6- 6.6) log10 copies/ml at baseline to 1.6 (1.6-2.3) log10 copies/ml after 12 months. Early CD4+ T-cell recovery was accompanied by a reduction of the expression levels of CD95 and CD38 on T-cells. Out of 42 patients with complete virological follow-up under HAART, 19 (45%) achieved concordant good immunological (gain of ≥100 CD4+ T-cells/µl above baseline) and virological (undetectable VL) responses after 12 months of treatment (intention-to-treat analysis). Neither a decreased expression of the T-cell activation markers CD38 and CD95, nor an increase in the percentage of naive T-cells reliably predicted good virological treatment responses in patients with good CD4+ T-cell reconstitution. Repeated measurement of CD4+ T-cell counts during HAART remains the most important parameter for immunologic monitoring. Substitution of repeated VL testing by determination of T-cell activation levels (e.g., CD38 expression on CD8+ T-cells) should be applied with caution.

Activation and maturation of peripheral blood T cells in HIV-1-infected and HIV-1-uninfected adults in Burkina Faso: a cross-sectional study

BackgroundWe wanted to explore to what extent environmental exposure to immune stimulants, which is expected to be more present in rural than in urban settings, influences T cell activation and maturation in healthy and in HIV-1-infected individuals in Burkina Faso in west Africa.MethodsThe proportion of circulating naïve T cells and the expression of the T cell activation markers, CD95 and CD38, were analyzed by immunophenotyping and three-colour flow cytometry in 63 healthy individuals and 137 treatment-naïve HIV-1-infected subjects from Ouagadougou (urban setting) and 26 healthy adults and 61 treatment-naïve patients from Nouna (rural).ResultsA slightly higher activation level of CD4+ and CD8+ peripheral blood T cells was seen in healthy adults living in Nouna than in those living in Ouagadougou. The percentages of naïve CD45RAbright CCR7+ T cells were not significantly different between both study sites. Taking into consideration that relatively more HIV-1-infected patients in Nouna were in an advanced disease stage, no relevant differences were seen in T cell activation and maturation between patients at both study sites. As expected, the percentage of CD95+ CD4+ and CD38+ CD8+ T cells and the respective antigen density on these cells was significantly higher in patients than in controls in both settings. The percentage of naïve CD8+ T cells was lower in HIV-1-infected subjects than in healthy controls irrespective of the study site, while a lower proportion of naïve CD4+ T cells in patients compared with controls was seen only in Nouna.ConclusionsEnvironmentally triggered immune activation may contribute to the increased expression of the activation markers CD95 and CD38 on peripheral blood T cells from healthy adults living in rural versus urban settings in Burkina Faso. T cell activation is further increased in HIV-1-infected individuals due to T cell loss and high plasma viral load levels. The observed variations in T cell activation levels or the proportion of naïve T cells in our study patients, however, are not explained by differences in CD4+ T cell counts or HIV-1 plasma viral load levels alone.