Evidence for a regulatory idiotypic network in the in vivo response to H-2 antigens.

Treatment of BALB/c mice with purified pig antiidiotype to 11-4.1 (anti-H-2Kk) monoclonal antibody has been found previously to induce the appearance of idiotype-bearing molecules (Id') in the serum of these mice, in the absence of detectable antigen-binding activity. In the present study we examined the effect of subsequent immunization of such antiidiotype-primed mice with the original H-2Kk antigen. Skin grafting of virgin BALB/c mice with BALB.K skin did not generate any detectable Id' antibodies when tested by enzyme-linked immunosorbent assay (ELISA). In contrast, grafting of antiidiotype-primed mice with BALB.K skin specifically boosted ther serum level of Id' molecules. Challenge of antiidiotype-primed mice with either B10.D2 or rat skin had no effect on the production of such Id' molecules. Absorption studies demonstrated that the majority of Id' molecules induced by H-2Kk antigenic stimulus and detected in ELISA are antigen-nonbinding molecules, thus indicating specific restimulation by the original H-2Kk antigen of nonbinding idiotype-positive B cell clones. The relevance of these findings to the existence of network interactions in the immune response to H-2 antigens is discussed

Idiotypes of anti-Ia antibodies. I. Expression of the 14-4-4S idiotype in humoral immune responses.

The idiotype of a mouse monoclonal anti-I-E antibody, 14-4-4S, has been studied using a heterologous anti-idiotypic reagent. This antibody recognizes Ia. 7, an antigenic specificity present in all strains expressing a product of the I-E subregion. Expression of the 14-4-4S idiotype in humoral immune responses was analyzed by an idiotype-specific enzyme-linked immunosorbent assay system. The idiotype was readily detectable in C3H.SW anti-C3H alloantisera, the same immunization combination from which the hybridoma was derived. Absorption analysis demonstrated the anti-I-E specificity of the idiotype-positive molecules in these alloantisera. Penetrance of idiotype expression was high among individual C3H.SW immune mice (9 of 10 tested). To examine genetic requirements for idiotype expression, an immunization was performed using as responders CWB mice, congenic with C3H.SW but differing at the heavy chain allotype loci. Immune sera of individual CWB mice contained very little or no idiotype, demonstrating that levels of idiotype expression are influenced by allotype-linked genes, although the influence of other genes has not been ruled. The 14-4-4S idiotype therefore represents a shared idiotype of anti-Ia antibodies and provides opportunities for analysis of the idiotypes of cellular receptors for the corresponding Ia antigen

Characterization of mixed allogeneic chimeras. Immunocompetence, in vitro reactivity, and genetic specificity of tolerance.

Mixed allogeneically reconstituted mice (B10 + B10.D2----B10) that specifically accept B10.D2 tail skin allografts were examined for in vivo and in vitro immunocompetence, patterns of hematopoietic repopulation, and in vitro reactivity. In vitro, mixed allogeneic chimeras (B10 + B10.D2----B10) manifested specific tolerance in mixed lymphocyte reactions and cell-mediated lympholysis to B10 and B10.D2 splenocytes, with normal responses to third-party (B10.BR) cells. Such chimeras were immunocompetent in B cell and helper T cell responses, as assessed by their primary plaque forming cell responses to in vivo sheep red blood cell immunization. This is in contrast to fully allogeneic chimeras, which responded less well. In addition, survival of the mixed allogeneic chimeras in a conventional animal facility was superior to that of fully allogeneic chimeras, and similar to syngeneically reconstituted (B10----B10) mice. Specific tolerance to skin grafts, degree of allogeneic engraftment, and persistence of chimerism was also assessed in a noncongenic mixed allogeneic combination (B10 + C3H----B10). Such animals manifested specific hyporeactivity to C3H skin allografts, but eventual chronic rejection of the grafts occurred in spite of stable and persistent mixed chimerism. MHC-congenic (B10.BR) skin grafts were accepted indefinitely in the same animals, suggesting that skin-specific non-major histocompatibility complex antigens were responsible for rejection of the C3H skin allografts

Genetic control of the immune response to staphylococcal nuclease. VII. Role of non-H-2-linked genes in the control of the anti-nuclease antibody response

The role of non-H-2-linked genes in the control of the antibody response to staphylococcal nuclease has been investigated. 3 wk after immunization with nuclease in complete Freund's adjuvant, strain A/J (H-2 a) mice produced significantly higher titers of antibody than strain B10.A (H-2(a)) mice, whereas mice of strains A.BY (H-2(b)) and B10 (H-2(b)) produced barely detectable titers. With hyperimmunization, A/J and A.BY mice reached the same peak levels for antibody titers, both severalfold higher than those reached by B10.A and B10 mice. Analysis of the specificity of antibodies by assessment of binding to two fragments of nuclease showed similarities between strains of the same H-2 haplotype. These results suggest that although H-2-1inked genes determined initial responsiveness at 3 wk and the relative proportions of antibodies directed toward different antigenic determinants on the nuclease molecule, non-H-2-linked genes determined the overall magnitude of the hyperimmuneresponse. Measurement of the affinity of the antibodies to the nuclease fragment (1-126) showed that strains B10 and B10.A produced antibodies with 7- to 10-fold higher affinity than comparable antibodies from strains A.BY and A/J. In a backcross of (B10.A × A/J) × B10.A, the level of antibody segregated independently of the Ig-1(e) C(H) allotype and the A/J anti-nuclease idiotypes. Thus, a gene(s) linked to neither H-2 nor heavy chain structural genes appears to control the aggregate response to antigenic determinants on the nuclease molecule independent of subspecificities of these antibodies or their idiotype

Developing countries and neglected diseases: challenges and perspectives

It is now commonly admitted that the so-called (most) neglected tropical diseases have been given little attention. According to World Health Organization, neglected diseases are hidden diseases as they affect almost exclusively extremely poor populations living in remote areas beyond the reach of health service. The European Parliament recognised that, to our shame, Neglected Diseases have not received the attention they deserve from EU actions. In the Millennium Development Goals they were given very little attention and mentioned just as other disease. Investing in drugs for these diseases is thought to be not marketable or profitable. However, despite their low mortality, neglected diseases are causing severe and permanent disabilities and deformities affecting approximately 1 billion people in the world, yielding more than 20 millions of Disability Adjusted Life Years (56.6 million according to Lancet's revised estimates) and important socio-economic losses. Urgent pragmatic and efficient measures are needed both at international and national levels

Evolutionary Instability of Symbiotic Function in Bradyrhizobium japonicum

Bacterial mutualists are often acquired from the environment by eukaryotic hosts. However, both theory and empirical work suggest that this bacterial lifestyle is evolutionarily unstable. Bacterial evolution outside of the host is predicted to favor traits that promote an independent lifestyle in the environment at a cost to symbiotic function. Consistent with these predictions, environmentally-acquired bacterial mutualists often lose symbiotic function over evolutionary time. Here, we investigate the evolutionary erosion of symbiotic traits in Bradyrhizobium japonicum, a nodulating root symbiont of legumes. Building on a previous published phylogeny we infer loss events of nodulation capability in a natural population of Bradyrhizobium, potentially driven by mutation or deletion of symbiosis loci. Subsequently, we experimentally evolved representative strains from the symbiont population under host-free in vitro conditions to examine potential drivers of these loss events. Among Bradyrhizobium genotypes that evolved significant increases in fitness in vitro, two exhibited reduced symbiotic quality, but no experimentally evolved strain lost nodulation capability or evolved any fixed changes at six sequenced loci. Our results are consistent with trade-offs between symbiotic quality and fitness in a host free environment. However, the drivers of loss-of-nodulation events in natural Bradyrhizobium populations remain unknown

Pattern-Sensitive Epilepsy. I: A Demonstration of a Spatial Frequency Selective Epileptic Response to Gratings

Rare individuals suffer epileptic seizures when they view certain images, particularly stripes. Contrast-threshold functions (the ability to see faint stripes of various widths) were determined for two pattern-sensitive brothers, and the epileptogenicity of various patterns was assessed for one of them. Sine wave grating contrast-detection thresholds for the two subjects were essentially normal, with lowest thresholds at approximately 2 cycles/ degree (c/deg). Epileptiform discharges occurred maximally at 5 c/deg with a 1-octave 50% bandwidth. Pattern epileptogenicity was increased by the addition of a third harmonic sine wave grating to its fundamental, but was unaffected by the phase relation of the two gratings. The frequency selectivity of epileptic responsiveness was quantitatively similar to a “spatial frequency channel.” Inhibitory interactions were not present. The findings suggest relations between the phenomena of pattern-sensitive epilepsy and hypothesized spatial frequency channels which merit further exploration. RESUMEN De manera excepcional, hay personas que pueden tener ataques epilÉpticos cuando ven ciertas imÁgenes, particularmente rayas. Se determinaron los umbrales para contrastes (la capacidad de ver rayas de diversas anchuras y muy tenues) en dos hermanos sensibles a patrones y se estableciÓ la epileptogeneidad de di versos patrones en uno de ellos. Los umbrales para contrastes fueron esencialmente normales en los dos sujetos cuando se utilizeÓ una rejilla hecha con ondas sinusoidales, siendo el umbral inferior unos 2 ciclos/ grado (c/deg). Descargas epileptiformes tuvieron lugar de modo mÁximo a 5 c/deg con una amplitud de banda del 50% de una octava. la capacidad epileptogÉnica del partÓn aumentÓ cuando se aÑadiÓ una tercera sinusoide armÓnica a la rejilla base pero esa capacidad no se viÓ alterada por la relaciÓn de fase entre las dos rejillas. La selectividad de la frecuencia de la respuesta epileptogÉnica fue cuantitativamente similar al “canal de frecuencia espacial”. No se observaron interacciones inhibitorias. Los hallazgos sugieren que hay relaciones entre la epilepsyÍa secundaria a patrones visuales y los hipotÉticos canales de frecuencia espacial, lo cual merece mÁs investigaciÓn.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65270/1/j.1528-1157.1980.tb04075.x.pd

Identification of the initial molecular changes in response to circulating angiogenic cells-mediated therapy in critical limb ischemia

BackgroundCritical limb ischemia (CLI) constitutes the most aggressive form of peripheral arterial occlusive disease, characterized by the blockade of arteries supplying blood to the lower extremities, significantly diminishing oxygen and nutrient supply. CLI patients usually undergo amputation of fingers, feet, or extremities, with a high risk of mortality due to associated comorbidities.Circulating angiogenic cells (CACs), also known as early endothelial progenitor cells, constitute promising candidates for cell therapy in CLI due to their assigned vascular regenerative properties. Preclinical and clinical assays with CACs have shown promising results. A better understanding of how these cells participate in vascular regeneration would significantly help to potentiate their role in revascularization.Herein, we analyzed the initial molecular mechanisms triggered by human CACs after being administered to a murine model of CLI, in order to understand how these cells promote angiogenesis within the ischemic tissues.MethodsBalb-c nude mice (n:24) were distributed in four different groups: healthy controls (C, n:4), shams (SH, n:4), and ischemic mice (after femoral ligation) that received either 50 mu l physiological serum (SC, n:8) or 5x10(5) human CACs (SE, n:8). Ischemic mice were sacrificed on days 2 and 4 (n:4/group/day), and immunohistochemistry assays and qPCR amplification of Alu-human-specific sequences were carried out for cell detection and vascular density measurements. Additionally, a label-free MS-based quantitative approach was performed to identify protein changes related.ResultsAdministration of CACs induced in the ischemic tissues an increase in the number of blood vessels as well as the diameter size compared to ischemic, non-treated mice, although the number of CACs decreased within time. The initial protein changes taking place in response to ischemia and more importantly, right after administration of CACs to CLI mice, are shown.ConclusionsOur results indicate that CACs migrate to the injured area; moreover, they trigger protein changes correlated with cell migration, cell death, angiogenesis, and arteriogenesis in the host. These changes indicate that CACs promote from the beginning an increase in the number of vessels as well as the development of an appropriate vascular network.Institute of Health Carlos III, ISCIII; Junta de Andaluci