Induction of an antibody response in cultures of human peripheral blood lymphocytes

A culture system is descirbed which provides adequate conditions for in vitro immunization of humand peripheral blood lymphocytes to heterologous erythrocytes. Making use of this method we could obtain, with a number of different donors, an antibody response which peaked at about day 8 of culture with 30-300 plaque-forming cells (PFC) per 10(6) input lymphocytes. However, in a number of experiments poor or negative results were obtained, even with donors that had previously given good response. This variability in the results was shown not to be due to a too low number of precursor cells present in the blood and could be overcome by treating the cells, before initiation of the culture, with a factor produced by mouse T cells educated to sheep erythrocytes (SRBC). Under these conditions a PFC responce was obtained which peaked at about day 8 and which in some experiments could be as high as 20,000 PFC per 10(6) input lymphocytes. Paralleling the increase in PFC was an increase in cell number. The cells recovered from the treated cultures were at all times more numerous than in the nontreated cultures. The height of both the proliferative and antibody-producing responses varied from experiment to experiment, a higher proliferative response, accompanying a higher PFC response. Although the mechanisms that are at the basis of the antibody response in vitro described in this paper still need to be clarified, this system may become a useful tool in studying the immune response in man.

En bloc spondylectomy reconstructions in a biomechanical in-vitro study

Wide surgical margins make en bloc spondylectomy and stabilization a referred treatment for certain tumoral lesions. With a total resection of a vertebra, the removal of the segment's stabilizing structures is complete and the instrumentation guidelines derived from a thoracolumbar corpectomy may not apply. The influence of one or two adjacent segment instrumentation, adjunct anterior plate stabilization and vertebral body replacement (VBR) designs on post-implantational stability was investigated in an in-vitro en bloc spondylectomy model. Biomechanical in-vitro testing was performed in a six degrees of freedom spine simulator using six human thoracolumbar spinal specimens with an age at death of 64 (+/- 20) years. Following en bloc spondylectomy eight stabilization techniques were performed using long and short posterior instrumentation, two VBR systems [(1) an expandable titanium cage; (2) a connected long carbon fiber reinforced composite VBR pedicle screw system)] and an adjunct anterior plate. Test-sequences were loaded with pure moments (+/- 7.5 Nm) in the three planes of motion. Intersegmental motion was measured between Th12 and L2, using an ultrasound based analysis system. In flexion/extension, long posterior fixations showed significantly less range of motion (ROM) than the short posterior fixations. In axial rotation and extension, the ROM of short posterior fixation was equivalent or higher when compared to the intact state. There were only small, nonsignificant ROM differences between the long carbon fiber VBR and the expandable system. Antero-lateral plating stabilized short posterior fixations, but did not markedly effect long construct stability. Following thoracolumbar en bloc spondylectomy, it is the posterior fixation of more than one adjacent segment that determines stability. In contrast, short posterior fixation does not sufficiently restore stability, even with an antero-lateral plate. Expandable verses nonexpandable VBR system design does not markedly affect stability.

HIV-1 gp120 accelerates Fas-mediated activation-induced human lamina propria T cell apoptosis

Intestinal mucosa represents an important portal of entry of HIV and a site of virus reservoir and active replication. Recently, in HIV patients, an early depletion of intestinal lamina propria T lymphocytes (LPT) has been described. HIV-1 gp120 has been demonstrated to promote apoptosis in noninfected isolated peripheral blood T cells, therefore we investigated whether gpl20 modulates apoptosis of normal human intestinal lamina propria T cells. Purified T cells were obtained by immunomagnetic negative selection from human lamina propria mononuclear cells isolated from surgical specimens by enzymatic procedure. Cells were incubated with or without recombinant gpl20 (10 microg/ml) and cultured either in the absence of any stimulus or in the presence of plate-bound anti-CD3 Ab (OKT3) or soluble anti-CD2 Ab (T11(2) + T11[3]). Apoptosis was assessed by flow cytometric analysis after propidium iodide staining. We demonstrated that preincubation of normal LPT cells with HIV-1 gpl20 accelerates the apoptosis observed during CD2-pathway stimulation of LPT cells. This process is mediated by Fas/Fas ligand interaction and related to an increased induction of Fas ligand mRNA by gpl20. Therefore HIV-1 gp120 could contribute to the depletion of noninfected LPT cells inducing a premature cell death.

Surgical management of recurrent thoracolumbar spinal sarcoma with 4-level total en bloc spondylectomy: description of technique and report of two cases

INTRODUCTION

The descriptions of total spondylectomy and further development of the technique for the treatment of vertebral sarcomas offered for the first time the opportunity to achieve oncologically sufficient resection margins, thereby improving local tumor control and overall survival. Today, single level en bloc spondylectomies are routinely performed and discussed in the literature while only few data are available for multi-level resections. However, due to the topographic vicinity of the spinal cord and large vessels, the multisegmental resections are technically demanding, represent major surgery and only few case reports are available. Surgical options are even more limited in cases of revision surgery and local recurrences when en bloc spondylectomy was considered to be not feasible due to high risk of vital complications in expanding resection margins. Deranged anatomy, implants in situ and extensive intra-/paraspinal scar tissue formation resulting from previously performed approaches and/or radiation are considered the principal complicating factors that usually hold back spine surgeons to perform revision for resection leaving the patient to palliative treatment.

METHODS

We present two patient cases with previously performed piecemeal vertebrectomy in the thoracic spine due to a solitary high-grade spinal sarcoma. After extensive re-staging, both patients underwent a multi (4)-level en bloc spondylectomy in our department (one patient with combined en bloc lung resection). Except a local wound disturbance, there was no severe intra- or postoperative complication.

RESULTS

After multilevel en bloc spondylectomy both patients showed a good functional outcome without neurological deficits, except those resulting from oncologically scheduled resection of thoracic nerve roots. After a median follow-up of 13 months, there was no local recurrence or distant metastasis. The reconstruction using a posterior screw rod system that is interconnected to an anterior vertebral body replacement with a carbon composite cage showed no implant failure or loosening. In summary, the approach of a multilevel en bloc surgery for revision and oncologically sufficient resection in cases of spinal sarcoma recurrences seems possible. However, interdisciplinary decision making in a tumor board, realistic evaluation of surgical resectability to attain tumor free margins, advanced experiences in spinal reconstructions and involvement of vascular, visceral and thoracic surgical expertise are essential preconditions for acceptable oncological and functional outcome.

Ultrasono-anatomy of the ankle ligaments

The ligaments of the ankle are superficial and easily accessible at ultrasonography. Surprisingly, the reliability of this technique has never been proven. With this goal in mind, ten ankles were subjected to a ultrasono-anatomic comparison. The five principle ligamentous fascicles (three on the lateral side and two on the medial side) measured at ultrasonography and the values verified after dissection. This study shows that the ligaments of the ankle are analyzed with ultrasonography and that the measures done are valid and have a precision of 2 mm for the anterior fascicle and the lateral fascicle of the lateral ligamentous plane Due to its simplicity and its low price, ultrasonography appears to be an important method in evaluating the ligaments and the degree of seriousness of ankle sprains.

Antibody response of rabbit blood lymphocytes in vitro. Kinetics, clone size, and clonotype analysis in response to streptococcal group polysaccharide antigens

Peripheral blood lymphocytes (PBL) of rabbits previously hyperimmunized against streptococcal groups A and A-variant antigens were stimulated in vitro by the corresponding vaccines to produce group-specific antibody. This response was dependent on an optimal cell density (2 X 10(6) cells/ml), on the presence of antigen, it was specific and cross-reactive due to a shared rhamnose backbone of the two polysaccharide antigens, and it was highly selective, such that in a 42-55-day culture 1 out of 20 viable cells was a specific PFC. During the exponential increase of the antibody concentration at a constant number of PFC, antibodies were secreted at a rate of 2.4 X 10(4) molecules/s per cell until a plateau level of antibody (40 mug/culture) was reached. The microculture system was used to determine the minimal frequency of group polysaccharide-specific precursor cells in the blood. Independent of the time elapsed since the last immunization this frequency was 1-3 X 10(-5), i.e., in the range of 1-2.8 X 10(2) precursor cells per ml blood. This number was further used together with the clonotype analysis of the culture supernates to calculate the frequencies of precursors of major and minor clonotypes. A hierachy of persisting clonal memory precursor cells was found indicating that clonal dominance is determined by locked-in frequency patterns and therefore it is a phenomenon based on numbers of cells that respond to the antigen.

Electrophoretically homogeneous antibody synthesized by spleen foci of irradiated repopulated mice

10(6) splenocytes from primed donors were injected, together with sheep erythrocytes (SRBC), into X-irradiated syngeneic mice. 8 days later the spleens were excised and cut into small fragments, keeping track of their location in the organ. Each fragment was cultured individually for 24 hr in the presence of (14)C amino acids and the culture fluids were assayed for antibody activity. The antibody-producing fragments were found to be clustered in few restricted areas (foci) surrounded by negative tissue. The anti-SRBC antibody from single foci was purified by absorption on stroma followed by acid elution. Thereafter, it was subjected to electrophoresis and immunoelectrophoresis. The radioautography of the runs showed a considerable degree of homogeneity. Distinct and sharp spikes were localized in the beta and gamma region. The pattern of each focus is unique from the point of view of the number of spikes and their mobility. Eluates obtained from many pooled fragments gave a broad radioactive smear in beta-gamma region. Many foci synthesized antibody migrating as a single band. This homogeneous protein is probably the product of a clone of cells homogeneously differentiated. However, some foci producing two and probably more antibody bands were also encountered. Two interpretations of the finding can be given. Either more than one precursor may participate in the formation of a focus or a differentiation switch may occur during the clonal expansion.

Suppressor cells in rabbit peripheral blood

Rabbit peripheral blood leukocytes (PBL) added to cultures of autologous spleen cells, primed in vivo to sheep red cells, are able to suppress with high efficacy the secondary in vitro response of the spleen cells to that antigen. Removal of nylon wool adherent cells from PBL abolishes the suppressive effect. When the PBL are fractionated by velocity sedimentation the suppressor cells can be separated from the responding cells. The circulating lymphocytes, freed from the inhibiting effect, either by nylon wool absorption or by velocity sedimentation fractionation, are able to give a strong secondary in vitro anti-SRC response, in which the long latency period, usually observed when PBL are stimulated with antigen in culture, is abolished or at least reduced. The suppressor effect present in the PBL is not due to granulocytes, platelets or erythrocytes.

Three-dimensional stiffness in a thoracolumbar en-bloc spondylectomy model: a biomechanical in vitro study

BACKGROUND

In selected cases, en-bloc spondylectomy is the only option to reach wide resection margins for patients with malignant tumours of the thoracolumbar spine. These patients must be also provided a secure initial stabilization of the spine and this is the role of vertebral body replacements employed with posterior fixation systems. The aim of this study was to determine the postimplantation stiffness of a connected vertebral body replacement pedicle screw system in different implantation scenarios following an en-bloc spondylectomy. Reconstruction was varied by posterior fixation lengths and axial compression forces during implantation.

METHODS

Three-dimensional stiffness was assessed in 6 fresh frozen human spinal specimens (Th11-L3) using a six degree of freedom spine simulator. Following en-bloc spondylectomy reconstruction was performed using a carbon composite fibre vertebral body replacement connected to a posterior fixation system by two artificial pedicles. The spines were loaded with pure moments (7.5Nm) in the three main motion planes. The intersegmental rotations were measured between Th12 and L2.

FINDINGS

Reconstructions using long posterior fixation modes demonstrated significant (P<0.05) higher stiffness compared to short posterior fixations in all motion planes. In axial rotation short posterior fixation modes failed to reach the values of the intact state. Neither high nor low axial compression force during implantation showed a significant impact on postfusional stiffness.

INTERPRETATION

In this biomechanical model, the employed system should be implanted with a posterior fixation of two adjacent segments to the lesion in order to achieve a secure stabilization of the treated segment.

On the specific binding of protochlorophyllide and chlorophyll to different peptide chains

By means of labelling experiments with δ-[(3)H]aminolevulinic acid (ALA) and SDS acrylamide gel electrophoresis the following results were obtained with plantlets of Zea mays L.: Protochlorophyllide is associated with two peptide chains of the molecular weights (MW) 21000 and 29000, thus forming two protochlorophyllide holochromes. Chlorophyll may be associated with four peptide chains of MW 21000, 25000, 29000 and 70000, forming four chlorophyll holochromes. When plantlets are transfrrred to light, protochlorophyllide is converted to chlorophyll but this remains associated with the peptide chains MW 21000 and 29000; in addition, chlorophyll is synthesized from unmetabolized ALA and associated with peptide chains MW 25000 and 70000. These conversions occur both in dark-grown plantlets and in green plantlets transferred to darkness and then again exposed to light, but in the latter considerably faster than in the former. The results suggest the existence of two pathways for the formation of chlorophyll holochromes, one requiring a dark period followed by light, the other occurring without a dark phase. Light may not only be required for photoconversion of protochlorophyllide to chlorophyll, but may also be involved in the regulation of the formation of the protein-pigment complexes.

Antigen-specific antibody response induced in cultures of human blood lymphocytes in presence of polyethylene glycol

Human peripheral blood lymphocytes respond in vitro to sheep red blood cells (SRBC) with the appearance of numerous specific plaque-forming cells, if the Epstein-Barr virus (EBV) is added to the cultures together with the antigen. However, it was found that when polyethylene glycol (mol. wt. 6000) is included in the culture medium at a final concentration of 4%, antigen alone is able to induce an anti-SRBC response, with clear hemolytic plaques of regular size. Addition of EBV causes a further increase in the antigen-specific antibody response.

Increased PGE2 production mediates the in vitro inhibitory effect of the human immunodeficiency virus P24 immunosuppressive heptapeptide Ch7

Previous work from our laboratory demonstrated that a synthetic heptapeptide (Ch7), corresponding to a conserved sequence of human immunodeficiency virus (HIV) core protein p24 (amino acids 232-238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). Addition of recombinant human interferon-gamma (IFN-gamma) to Ch7-suppressed cultures restored the capacity to mount an antigen-specific antibody response, suggesting that a cytokine imbalance may be at the basis of the Ch7 immunosuppressive activity. In the present paper we show that the Ch7-dependent in vitro immunosuppression was accompanied by a significant up-regulation of prostaglandin E2 (PGE2) production and induction of interleukin-10 (IL-10)-secreting cells. In the presence of the PGE2 inhibitor indomethacin, IL-10 up-regulation was prevented and the induction of a specific antibody response was partially restored. PGE2 is indeed an important regulator of immune responses with the ability to differentially affect cytokine production. Thus, our results demonstrate that the Ch7 immunosuppressive epitope may primarily act by up-regulating PGE2 production and, through this mediator, by causing a cytokine dysregulation, finally responsible for immune response suppression.

Interferon-gamma (IFN-gamma) can counteract the in vitro inhibitory effect of an HIV p24 immunosuppressive heptapeptide

Previous work from our laboratory demonstrated that a synthetic heptapeptide (Ch7), corresponding to a conserved sequence of HIV core protein p24 (aa 232-238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). In the present study we show that Ch7 did not inhibit the induction of IFN-gamma-secreting cells nor the accumulation of IFN-gamma mRNA in antigen-stimulated cultures. However, delayed addition of recombinant human IFN-gamma to Ch7-suppressed cultures was able to restore fully the capacity to mount an antigen-specific antibody response. Thus, although the Ch7 immunosuppressive effect may not be directly related to a decreased production of IFN-gamma, an increased level of this cytokine is certainly able to counteract the negative effect of the peptide.

Induction of antibody forming cells with specificity for Candida albicans mannoproteins in cultures of human peripheral blood lymphocytes

A method is described for the induction of a specific antibody response to Candida albicans in cultures of normal human peripheral blood lymphocytes (PBL). PBL were cultured in the presence of whole C. albicans cells and the antibody response was evaluated by the ELISPOT technique, on plastic wells coated with a purified candidal cell well mannoprotein (MP). Under the conditions described here, a specific antibody response was obtained in all of the eight donors tested. The response was antigen-dependent and antigen-specific, peaked around day 10-12 of culture and the antibodies belonged to both the IgM and the IgG isotypes. By testing the cultured cells on MP from different Candida species, the method permitted the detection of antibodies directed against MP epitopes shared by C. albicans and C. parapsilosis.

Interleukin-12 up-regulates the induction of an antigen-specific antibody response in cultures of human lymphocytes

The influence of interleukin-12 (IL-12) on the induction of a specific antibody response to the T-dependent antigen sheep erythrocytes (SRBC) in cultures of human blood lymphocytes was investigated. The response, evaluated as number of antigen-induced antibody-producing cells, was greatly increased in the presence of IL-12. When a two-stage limiting dilution culture system was used, the plot of the number of seeded cells versus the logarithm of the fraction of negative cultures deviated from linearity in antigen- and IL-12-stimulated cultures. However, linearity was reached when IL-2 was added in the second stage. Under these latter conditions, since single-hit criteria were fulfilled, it was possible to estimate the frequency of SRBC-specific B cell precursors able to respond to the antigen and to show that such frequency was increased upon addition of IL-12. Thus, the enhancing effect of IL-12 may be based on an increased frequency of responding precursor cells. The results here presented demonstrate, to our knowledge for the first time, a definite role of IL-12 in the induction of a specific antibody response in human cells. Further, they stress the importance for such studies of appropriate in vitro systems. Finally, they show that the induction of primary immune responses in cultures of human peripheral blood lymphocytes mostly depends on the proper cytokine balance at different time points.

Bone sarcoma of the spine

Primary malignant bone tumors of the vertebral column, i.e., bone sarcomas of the spine, are inherently rare entities. Vertebral osteosarcomas and chordomas represent the largest groups, followed by the incidence of chondro-, fibro-, and Ewing's sarcomas. Detailed clinical and neurological examination, complete radiographic imaging [radiographs, computed tomography (CT), magnetic resonance imaging (MRI)], and biopsy are the decisive diagnostic steps. Oncosurgical staging for spinal tumors can serve as a decision-guidance system for an individual's oncological and surgical treatment. Subsequent treatment decisions are part of an integrated, multimodal oncological concept. Surgical options comprise minimally invasive surgery, palliative stabilization procedures, and curative, wide excisions with complex reconstructions to attain wide or at least marginal resections. The most aggressive mode of surgical resection for primary vertebral column tumors is the total en bloc vertebrectomy, i.e., single- or multilevel en bloc spondylectomy. En bloc spondylectomy involves a posterior or combined anterior/posterior approach, followed by en bloc laminectomy, circumferential (360 degrees) vertebral dissection, and blunt ventral release of the large vessels, intervertebral discectomy and rotation/ en bloc removal of the vertebra along its longitudinal axis. Due to the complex interdisciplinary approach and the challenging surgical resection techniques involved, management of vertebral bone sarcomas is recommended to be performed in specific musculoskeletal tumor centers.

Induction of a specific antibody response to Bordetella pertussis antigens in cultures of human peripheral blood mononuclear cells

The role of specific antibodies in protective immunity to Bordetella pertussis has not yet been clearly defined. In the present work, the induction of a specific antibody response to B. pertussis in cultures of human peripheral blood mononuclear cells (PBMC) was investigated, on the assumption that the capacity of circulating lymphocytes to mount a specific response in vitro may provide a useful parameter for the evaluation of protective immunity. When PBMC from normal adult donors were cultured with a heat-inactivated B. pertussis whole-cell suspension, cells secreting antibodies to pertussis toxin, pertactin and filamentous haemagglutinin were generated consistently. The antibody response peaked between days 7 and 11 of culture and the antibodies produced were exclusively of the IgM class.

Complement-inactivating proteinase(s) from Clostridium histolyticum

A proteinase fraction inhibiting the hemolytic activity of guinea pig complement was obtained from supernatant fluids of Clostridium histolyticum cultures and purified 150- to 350-fold by ammonium sulfate precipitation, Sephadex G-75 gel filtration, and diethylaminoethyl cellulose chromatography. An assay was developed based on the inactivation of hemolytic complement. Partially purified anticomplementary preparations were active against casein and were capable of "solubilizing" Escherichia coli endotoxin. Two components were found by differential heat inactivation, with complement and casein as substrates, but only one of these components was active against endotoxin. The more heat-stable activity, showing 50% inactivation at about 47 C, was characterized as to pH and ionic strength optima and sensitivity to reagents such as cysteine, beta-mercaptoethanol, ethylenediaminetetraacetate, and heavy metals.

An HIV p24 heptapeptide down-regulates antigen-specific responses in vitro interfering at the level of the T3-Ti complex

Ch7 (RGSDIAG), a synthetic heptapeptide derived from a conserved region of HIV p24 (aa 232-238), was previously shown to suppress antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). We show in this paper that Ch7 is the shortest peptide retaining full inhibitory capacity. Further, the peptide inhibited efficiently and in a dose-dependent manner the induction of a specific antibody response to the antigens SRC (sheep red cells) and Candida albicans but did not exert any effect on the induction of immunoglobulin-secreting cells in PWM-stimulated cultures. Finally, Ch7 inhibited anti-CD3-induced lymphoproliferation but did not affect anti-CD2 activation. These results suggest that a conserved epitope of HIV p24 may be able to prevent the induction of antigen-specific antibody responses by interfering with lymphocyte activation via the T3-Ti complex, resulting in the abrogation of immune functions that are defective in HIV-infected individuals.