Follicular dendritic cells specifically express the long CR2/CD21 isoform.

This paper describes an antibody (mAb 7D6) that specifically recognizes human follicular dendritic cells (FDCs). By expression cloning, a cDNA clone encoding for the long human CR2/ CD21 isoform (CD21L) that contains an additional exon (10a) was isolated. We demonstrated that FDCs selectively express CD21L, while B cells selectively express the short CR2/CD21 lacking exon 10a (CD21S). By screening mouse Ltk- cells transfected with the CD21L cDNA, we further showed that the other two anti-human FDC mAbs DRC-1 and KiM4 also recognize CD21L. Thus, CD21L represents the first characterized human FDC-specific molecule, which may confer unique functions of FDCs in germinal center development.

T cell interleukin-17 induces stromal cells to produce proinflammatory and hematopoietic cytokines.

Analysis of the cDNA encoding murine interleukin (IL) 17 (cytotoxic T lymphocyte associated antigen 8) predicted a secreted protein sharing 57% amino acid identity with the protein predicted from ORF13, an open reading frame of Herpesvirus saimiri. Here we report on the cloning of human IL-17 (hIL-17), the human counterpart of murine IL-17. hIL-17 is a glycoprotein of 155 amino acids secreted as an homodimer by activated memory CD4+ T cells. Although devoid of direct effects on cells of hematopoietic origin, hIL-17 and the product of its viral counterpart, ORF13, stimulate epithelial, endothelial, and fibroblastic cells to secrete cytokines such as IL-6, IL-8, and granulocyte-colony-stimulating factor, as well as prostaglandin E2. Furthermore, when cultured in the presence of hIL-17, fibroblasts could sustain the proliferation of CD34+ hematopoietic progenitors and their preferential maturation into neutrophils. These observations suggest that hIL-17 may constitute (a) an early initiator of the T cell-dependent inflammmatory reaction; and (b) an element of the cytokine network that bridges the immune system to hematopoiesis.

[Treatment of children born of AIDS mothers in Tsevie hospital regional center, Togo]. / Prise en charge des enfants nés de mères infectées par le VIH au centre hospitalier régional de Tsévié, Togo.

The aim of this survey was to describe the components of the children medical care follow-up in the protocol of prevention of HIV/Aids from mother to child by nevirapine intake. A four-year retrospective study was carried out in Tsevie hospital regional center 90 children and their pregnant mothers who received nevirapine were recorded. 75 children received breast feeding. There was no follow-up for 42% of the children. The weight growth was correct in 90% of the children effectively followed. 49% of the children were completely vaccinated to PEV. The average children medical check up was 3.1 (minimum 1 maximum 8). The average age for breast feeding weaning was 6.2 months. The mother to child transmission rate was globally estimated at 12.5% at 18 months. 12 children (13%) died before HIV serology. The survey confirms the potency of nevirapine in preventing HIV transmission from mother to child and lays emphasis on real problems for which appropriate solutions should be found.

Epitope mapping of recombinant human gamma interferon using monoclonal antibodies.

Five monoclonal antibodies (MAbs B22, B27, 3-6, 32 and 35) specific for human recombinant IFN-gamma were characterized. These MAbs were used to set up quantitative sandwich ELISAs which allowed the detection of 1.25 ng/ml of IFN-gamma when diluted in normal human serum. Epitope mapping of the IFN-gamma molecule using these MAbs demonstrated that antibodies 3-6 and 32 which did not inhibit the biological activity of IFN-gamma recognized an epitope localized on the 15 C-terminal amino acids, suggesting that this portion of the molecule was not implicated in the biological activity of IFN-gamma. Sandwich ELISAs were performed using various pairs of MAbs. The level of reactivity obtained when antibodies B22 and B27 were used simultaneously as catcher and tracer was similar to the result obtained with two antibodies recognizing different epitopes. These results confirm that the IFN-gamma molecule is a dimer in solution and indicate that the two sites of the IFN-gamma dimeric molecule which are associated with the biological activity (epitope B22/B27) are fully exposed. In contrast, the C-terminus is only partially accessible to the antibodies 3-6/32, suggesting that the dimerization of IFN-gamma molecule results in the interaction of regions of the monomers that are homologous and adjacent to the C-terminus.

Generation and characterization of a human monoclonal autoantibody that acts as a high affinity interleukin-1 alpha specific inhibitor.

Interleukin-1 (IL-1) defines two polypeptides, IL-1 alpha and IL-1 beta, that possess a wide spectrum of biological effects. Two natural antagonists of IL-1 action have been characterized: the IL-1 receptor antagonist (IL-1Ra) and a soluble form of the type II IL-1 receptor. Neutralizing autoantibodies to IL-1 alpha have also been detected in sera of healthy individuals and patients with autoimmune or inflammatory diseases. To characterize such antibodies molecularly, we attempted to generate B cell clones producing anti-IL-1 alpha human monoclonal antibody (HuMAb) by combining Epstein-Barr virus-immortalization and CD40-activation of B lymphocytes from individuals with circulating anti-IL-1 alpha. We describe herein the generation and properties of a natural IgG4/kappa anti-IL-1 alpha monoclonal autoantibody, HuMAb X3, that bound specifically to human IL-1 alpha, but not to IL-1 beta and IL-1Ra, with a high affinity (Kd = 1.2 x 10(-10)M). HuMAb X3 inhibited IL-1 alpha binding to IL-1 receptors and neutralized biological activities of both recombinant and natural forms of IL-1 alpha. A recombinant form of HuMAb X3 was found to display identical specific IL-1 alpha antagonism. The presence of somatic mutations within X3 variable regions suggests an antigen-driven affinity maturation. This study extends the demonstration of the presence of high affinity neutralizing anti-IL-1 alpha autoantibodies that can function as a third type of IL-1 antagonist.

[Ambulatory management of sickle cell disease: evaluation of the first year follow up of patients in the pediatric department of Lomé (Togo)]. / Prise en charge ambulatoire des drépanocytaires: évaluation de la première année de suivi des patients dans le service de pédiatrie de Lomé (Togo).

BACKGROUND: This study is an evaluation of the first year ambulatory follow up of patients from the sickle-cell care centre of the paediatric ward of the teaching hospital in Lomé-Tokoin. PATIENTS AND METHODS: Togo is situated in the epicentre of the Benin haplotype. A total of 132 patients (109 SS, 22 SC and 1 S beta zero thal) followed up during one year from their admission date (period of 1st January 1996 to 31st December 1997). 132 patients were included in the study. RESULTS: The patients' age varied, for the majority, between 2 months and 15 years, but a few adults (15%) were included in the study. Information was collected from the hospital files and health cards, which unfortunately did not have specific entrees for sickle cell disease. Clinical features revealed that the frequency of tooth decay and chronic persistent splenomegaly was low when compared to the rates in central Africa (Bantu haplotype). Laboratory findings lead to the conclusion that some analysis are relevant such as the dosage of the G6PD activity (24.1% of patients were deficient), parasitologic analysis of faeces (positive in 22.5%), retinal fluoro-angiography (32.2% of ocular lesions), and cardiologic check-up. On the other hand, scanning of biliary tracts and systematic X-rays of the hips seems to be secondary. Some positive results were noticed by the scanning of biliary tracts without any therapeutic decisions in non-symptomatic patients; no case of osteonecrosis was detected by the X-rays. The mean haemoglobin level was 7.4 +/- 1.4 g/dl for the SS and 10.7 +/- 2.4 g/dl for the SC. The mean MCV were 91.3 +/- 10.1 fl and 82.1 +/- 7.7 fl, respectively. Specific vaccinations were not well performed because of their high cost. CONCLUSION: In order to carry on and improve the ambulatory management of patients with sickle cell disease, it is important in low income countries, such as Togo, to target the necessary laboratory tests for an initial and annual check-up. Solidarity networks for patients should be promoted and effective involvement of the health authorities ensured.

[Treatment of cerebral malaria in African children by intravenous quinine: comparison of a loading dose regimen to a regimen without a loading dose]. / Traitement du paludisme cérébral de l'enfant africain par les sels de quinine: comparaison d'un schéma avec dose de charge à un schéma classique sans dose de charge.

OBJECTIVE: To compare in a randomized study the efficacy and the toxicity of the new WHO intravenous quinine treatment of cerebral malaria including a loading dose regimen to a regimen without loading dose. PATIENTS AND METHODS: Seventy-two children eight months to 15 years of age with cerebral malaria were included. Quinine formiate was administered to a group of 35 patients in an initial loading dose of 20 mg salt/kg (equivalent to 17.5 mg/kg of the base) in 10 mL/kg of 5% glucose over four hours, followed eight hours later by a maintenance dose quinine of 10 mg salt/kg (equivalent to 8.7 mg/kg of the base) dissolved in 15 mL/kg of 5% glucose over and every 12 hours. The second group of 37 patients received intravenous quinine 15 mg salt/kg (13.1 mg of base) dissolved in 15 mL/kg of 5% glucose infused over 6 to 8 hours, every 12 hours. In both groups this treatment was continued until the patient could swallow, then quinine tablets were given to complete seven days treatment. The assessment of cardiovascular side effects was made by an ECG at admission, the 4th hour, the 24th hour and at the end of treatment for each patient. RESULTS: Coma mean durations were similar in the two groups: 35.5 +/- 17.8 hours and 28.6 +/- 14.4 hours respectively for the loading dose group and the group without loading dose. The two groups were comparable also for the decrease evolution of parasitemia. Case-fatality rates were also similar: 95% of healing at the 72nd hour and a lethality rate between 5 and 6% in the two groups. But a significant increase of the body temperature was noted between the 51st and the 63rd hour in the group without loading dose. No significant cardiovascular toxicity was noticed in the two groups. The mean cost of the loading dose regimen was less than that of the second regimen. CONCLUSION: The loading dose regimen of quinine is well tolerated and it seemed slightly more effective than the regimen without loading dose. In cases of contra-indications (patients who recently received quinine, mefloquine or halofantrine), regimens without loading dose, which remains effective, should be used.

[Epidemiologic and etiologic features of urinary infections in children at the pediatrics service of the CHU-Campus de Lome (Togo)]. / Aspects épidémiologiques et étiologiques de l'infection urinaire de l'enfant dans le service de pédiatrie du CHU-Campus de Lomé (Togo).

From 1st January 1989 to 31th December 1997, 175 infants (108 females and 67 males) were hospitalised and treated at the pediatric service of CHU-Campus for urinary tract infection; this study follows the observation of the increasing of urinary tract infection in several centers of health in Togo; the aim of this study was to have a list the contributing factors, to understand the mechanism of such infection in order to reduce its frequency and the high percent of the mortality; the diagnosis of urinary tract infection was given by the result of the cytobacteriological exam of the urine which shows the pathological germ; others forms of the investigation, as abdominal echography were used also to look for the etiology of the urinary tract infection; but, the deficit of the of the medical imagery or the old material of the laboratories limited the searching of urinary tract infection etiology; cured infants were declared on the basis of absence of pathological germ in the result of the cytobacteriological exam control of the urine; the prevalence of the urinary tract infection was 8.29% with an incidence of 7.84% at the pediatric service of CHU-Campus; clinics symptoms were atypic and polymorphic; but the fever was the first clinical sign in the newly born and the urological signs were clear only from two to thirty months; 141 children (80.57%) were cured and 34 presented the complications with 3.43% of mortality; preventive measures on the urinary tract infection in infancy were proposed for the children parents and the practical physicians; these measures included information, education and communication (IEC) on the urinary tract infection, the symptomatology and the cytobacteriological exam of the urine.

[Diluted injectable quinine in the intramuscular and intrarectal route: comparative efficacity and tolerance in malaria treatment for children ]. / Quinine injectable diluee en intramusculaire et en intrarectal: efficacite et tolerance comparees dans le traitement du paludisme de l'enfant.

The intramuscular (i.m.) route is generally used for treatment of childhood falciparum malaria in outlying health care units in Togo. The purpose of this randomized therapeutic trial was to compare the efficacy and tolerance of diluted injectable quinine administered by the i.m. versus intrarectal (IR) route. A total of 64 children ranging in age from 8 months to 15 years were treated, i.e. 32 for each administration route. All children presented uncomplicated falciparum malaria in association with vomiting in 30 cases, a single unrecurring seizure with postictal coma lasting less than 30 minutes in 25 patients, or prostration without neurological manifestations in 9. Injectable quinimax (an association of cinchona alkaloids) was diluted to a concentration of 60 mg base/ml for i.m. injection into the thigh and 30 mg base/ml for use by the IR route. Administration was performed every 12 hours for 72 hours at a dose of 12.5 mg/kg for patients in the i.m. group or at a dose of 15 mg/kg in the IR group. The anus and lower rectal mucosa were examined using an anal valve before and after treatment using the IR route. Analysis of mean temperature curves demonstrated no significant difference between the clinical effectiveness of quinimax administered by the i.m. versus IR route (p > 0.05). Similar effect were also observed on parasitemia which disappeared completely in all patients by the end of the 72-hour treatment. The main problems were insufficient product retention requiring re-administration in 25% of patients in IR group and residual pain at the injection site in 12.5% of patients in the i.m. group. Endoscopic examination revealed no evidence of ulceration or necrosis of the anorectal mucosa. These findings indicate that administration of diluted injectable quinine by IR route is an effective, well-tolerated alternative for treatment of childhood falciparum malaria. It should be used preferentially in outlying health care units in patients presenting severe malaria pending transfer to an hospital, or signs of "intermediate severity" such as hyperpyrexia, hyperparasitemia, unrepeated seizure, or intensive vomiting.

[Evaluation of the glycemia of low-weight newborns within the 24th hour of life at Lomé University Hospital (Togo)]. / Évaluation de la glycémie des nouveau-nés de petits poids avant la 24(e) heure de vie au CHU-Tokoin de Lomé

OBJECTIVE: To assess the glycemia of low-weight newborns (LWNBs) during their first 24h of life as well as their mother's glycemia. PATIENTS AND METHOD: This was a cross-sectional prospective study within a case-control group, conducted at Lomé University Hospital (nationwide main hospital) from January to May 2006. One hundred thirty-nine LWNBs and 150 eutrophic term newborns (ETNBs), 98 mothers of LWNBs (MLWNBs), and 145 mothers of ETNBs (METNBs) were screened and monitored on glycemia dosage. RESULTS: The average glycemia level of the LWNBs (0.34 ± 0.27g/l) was significantly greater than the ETNBs' glycemia level (0.30 ± 0.14 g/l); it was nearly the same for the mean glycemia level of the MLWNBs (0.82 ± 0.2g/l) and the METNBs (0.77 ± 0.1g/l). Neonatal hypoglycemia during the first 24h of life was less frequent (RR=0.8) in the LWNBs (61.15%) than in the ETNBs (80%). The positive correlation between gestational age and glycemia was higher in the ETNBs (r=0.17) than in the LWNBs (r=0.07). This positive correlation between birthweight and glycemia was lower in the LWNBs (r=0.17) compared to the ETNBs (r=0.37); this was not the case within the group of the ETNBs (r=0.02) compared to the group of the LWNBs (r=0.34) concerning the correlation between the glycemia of mothers and newborns. CONCLUSION: The early hypoglycemia was much greater in the ETNBs compared to the LWNBs. Therefore, it is necessary to systematically start breastfeeding all newborns within their first hours of life whatever their gestational age, in order to solve these metabolic disorders.

A recombinant extracellular domain of the human interleukin 4 receptor inhibits the biological effects of interleukin 4 on T and B lymphocytes.

Human interleukin 4 (IL4) acts on various hematopoietic cell types through interaction with a specific cell surface receptor (IL4R), whose cDNA has been cloned. We have produced a cDNA encoding a soluble form of the extracellular domain of the human IL 4R (sIL4R) and describe here the capacity of sIL4R to antagonize the in vitro activities of IL4 on normal B and T lymphocytes. sIL4R inhibited IL4-induced proliferation of both phytohemagglutinin-preactivated peripheral blood mononuclear cells (PBMC) and anti-IgM co-stimulated tonsil B cells with similar efficiency. This inhibitory activity was specific since sIL4R did not affect IL2-dependent proliferation of these cells. sIL4R also blocked IL4-dependent induction of the low-affinity receptor for IgE on B cells and inhibited IgE production by IL4-activated PBMC. Thus, in contrast to the IL6R extracellular domain which stimulates IL6 biological activity, the IL4R extracellular domain is a powerful antagonist of its specific ligand.

Increased incidence of neutralizing autoantibodies against interleukin-1 alpha (IL-1 alpha) in nondestructive chronic polyarthritis.

Cytokines such as IL-1 and tumor necrosis factor alpha (TNF alpha) play a critical role in chronic joint inflammation and destruction. To study their regulation, we looked for circulating antiproinflammatory cytokine autoantibodies in 318 patients with chronic arthritis by immunoprecipitation with protein G. Anti-IL-1 alpha but not anti-IL-1 beta or anti-TNF alpha IgG antibodies were detected in 9% of blood donors and 18.9% of chronic arthritis patients. These antibodies were found more commonly and at a higher level in patients with nondestructive arthritis. Negative correlations were observed between the antibody levels and indices of disease activity and joint destruction. There was a negative association between the presence of anti-IL-1 alpha antibodies and that of HLA-DR4. These circulating anti-IL-1 alpha antibodies were not complexed with IL-1 alpha and could block specifically the biological activity of IL-1 alpha and its binding to membrane IL-1 receptors. These results indicate that these antibodies are beneficial, suggesting their contribution in the clinical presentation.

Internalization of human interleukin 4 and transient down-regulation of its receptor in the CD23-inducible Jijoye cells.

Human interleukin 4 (IL-4) specifically induces the low affinity receptor for IgE (Fc epsilon R2/CD23) on the surface of the Burkitt lymphoma cell line Jijoye. At 4 degrees C 125I-IL-4 specifically binds to high affinity receptors (Kd = 4-10 x 10(-11) M; Bmax, 600-1,200 sites/cell). Following a rapid temperature shift from 4 to 37 degrees C, 80% of the receptor-bound 125I-IL-4 disappeared from the cell surface within 20 min (t1/2 = 8.9 min). For every two internalized molecules of IL-4 (t1/2 = 13 min), one molecule of IL-4 dissociated from the cell surface (t1/2 = 25 min). More than 90% of the internalized IL-4 was released in a degraded form into the medium following first order kinetics (t1/2 = 68 min). Internalization was inhibited by cytoskeletal disrupting and lysosomotropic agents. Incubating cells with 1 nM IL-4 resulted in a rapid down-regulation of IL-4 receptors (75% loss after 2 h); a reexpression of receptor to control level occurred after 20 h in spite of the presence of a large excess of IL-4. Reexpression was delayed by chloroquine and blocked by cycloheximide and actinomycin D. By using the cross-linking agent bis(sulfosuccinimidyl)suberate, three polypeptides of Mr 130,000, 80,000, and 70,000 were specifically labeled with 125I-IL-4. These three polypeptides coordinately disappeared and reappeared with the 125I-IL-4 binding sites. The induction of Fc epsilon R2/CD23 required prolonged incubation (greater than 8 h) with IL-4 and thus may be dependent on the reexpression of IL-4 receptor.

Activation of human B lymphocytes through CD40 and interleukin 4.

We have produced and characterized a new CD40 monoclonal antibody, mAb 89, which in the presence of anti-IgM antibodies co-stimulates to induce B cell proliferation. mAb 89 activates resting B cells as shown by an increase in cell volume and an enhanced subsequent proliferation of B cells in response to anti-IgM antibody. However, mAb 89 does not prepare B cells to respond to the growth-promoting activity of interleukin (IL) 2 or IL 4. Unlike IL 2 and IL 4, mAb 89 only weakly stimulates the proliferation of anti-IgM pre-activated B cells. Thus, the activating properties of anti-CD40 are likely to explain its co-stimulatory effect on B cells. Interestingly, the anti-CD40 mAb 89 was found to act in synergy with IL 4, but not with IL 2, in co-stimulation and restimulation assays. In this respect, anti-CD40 does not induce a significant increase of B cell surface IL 4 receptors while IL 4, but not IL 2, induces a twofold increase of the CD40 antigen expression. Thus the synergistic interaction between IL 4 and anti-CD40 may be related to the IL 4-dependent increase of CD40 antigen expression.

The primary binding subunit of the human interleukin-4 receptor is also a component of the interleukin-13 receptor.

Interleukin (IL)-13 elicits a subset of the biological activities of the related IL-4. The basis of this functional similarity is that their specific cell-surface receptors (called IL-13R and IL-4R) are distinct, yet are complex and share a common subunit(s). The IL-4R primary binding subunit (called IL-4R alpha) does not by itself bind IL-13. We show that the ability of IL-13 to partially compete for IL-4 binding to some human cell types depended on co-expression of IL-4R and IL-13R. However, IL-13 binding was always associated with IL-4 binding. Hyper-expression of IL-4R alpha on cells expressing both IL-4R and IL-13R decreased their binding affinity for IL-4, abrogated the ability of IL-13 to compete for IL-4 binding, and yet had no effect on IL-13R properties. Anti-human IL-4R alpha monoclonal antibodies which blocked the biological function and binding of IL-4 also blocked the function and binding of IL-13. These data show that IL-4R alpha is a secondary component of IL-13R.

Delayed IgG2 humoral response in infants is not due to intrinsic T or B cell defects.

The physiologically low or absent IgG2 responses of infants have been attributed to T or B cell functional immaturity. We have analyzed the capacity of adult and neonatal T lymphocytes to secrete IgG2 switch factor (IgG2-SF) and the capacity of neonatal B cells to respond to such factors. The IgG2-SF capacity was assessed on CD40-activated naive B cells, measuring IgG2 by ELISA in supernatants of cultures performed in the presence of IL-10. T cells secreted IgG2-SF together with IL-2 and IFN-gamma, after activation with a combination of anti-CD2, anti-CD28 and phorbol myristate acetate (Th1-like activation). In contrast, activation with anti-CD3 and anti-CD28, which yielded IL-4 and IL-10 but neither IL-2 nor IFN-gamma (Th2-like activation), did not result in the secretion of IgG2-SF. The supernatant of activated neonatal T cells contained IgG2-SF. Neonates' B cells produced almost as much IgG2 as did naive adult B cells. The effect of IgG2-SF was further demonstrated by its ability to induce 3-15% of CD40-activated naive B cells to express cytoplasmic IgG2 regardless of the presence of IL-10. This study demonstrates that: (i) IgG2 switch can be T cell dependent in humans, (ii) IgG2-SF is produced with Th1-like cytokines and (iii) low IgG2 responses in infants do not result from either an inability of T cells to produce IgG2-SF or an inability of B cells to undergo IgG2 switch in vitro.