A. K. Lefvert

Idiotype‐specific T cells in multiple myeloma stage I: an evaluation by four different functional tests

Idiotype-specific T cells were characterized in patients with multiple myeloma stage I by analysing idiotype-induced DNA synthesis (3H-thymidine incorporation), IL-2 and IFN-gamma production at the single cell level (ELISPOT) (in vitro tests) and delayed type hypersensitivity (DTH) skin reaction (in vivo test). In seven out of eight patients at least one of the four tests was positive. In five patients three or more tests were positive. One patient was negative in all four tests. Six patients had both IL-2 and IFN-gamma-secreting cells and three of them also a DTH response. Furthermore, those three patients with a proliferative response also had IL-2 and IFN-gamma-secreting cells induced by the idiotype. The data indicate that part of the idiotype-specific T cell fraction belongs to the CD4 Th1 cell population. Whether CD8-specific T cells also were present could not be ruled out. The present study provides further support for the existence of idiotype-specific T cells in multiple myeloma. Such cells might be an important target for an immune-mediated therapeutic approach.

Mononuclear leukocytes exposed to oxidized low density lipoprotein secrete a factor that stimulates endothelial cells to express adhesion molecules

In animals fed a hypercholesterolemic diet, development of atherosclerosis is preceded by attachment of mononuclear leukocytes to the arterial endothelium. Early lesions begin to develop as monocytes migrate into the intima and ingest lipids. A major part of these lipids is believed to be derived from oxidatively modified low density lipoprotein (LDL). In the present study we demonstrate that human mononuclear leukocytes exposed to low concentrations of copper-oxidized LDL secrete one or several factors that stimulate the expression of intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule (VCAM-1) and endothelial selectin (E-selectin-1, ELAM-1), whereas native LDL was found to be without effect. Exposure of endothelial cells to non-conditioned medium containing oxidized LDL did not influence the expression of adhesion molecules. Incubation of endothelial cells with conditioned medium from mononuclear cells grown in the presence of oxidized LDL also resulted in a three-fold increase in the binding of monocytoid U937 cells. The present findings suggest that mononuclear leukocytes exposed to oxidatively modified LDL in early atherosclerotic lesions may stimulate the recruitment of other leukocytes by secreting cytokines which induce the expression of adhesion molecules on the endothelium.

Aggressive Behavior Linked to Corticotropin-Reactive Autoantibodies

BACKGROUND Altered stress response is characteristic for subjects with abnormal aggressive and antisocial behavior, but the underlying biological mechanisms are unclear. We hypothesized that autoantibodies (autoAbs) directed against several stress-related neurohormones may exist in aggressive subjects. METHODS Using enzyme-linked immunosorbent assay, we studied whether autoAbs directed against corticotropin (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), oxytocin, and vasopressin are present in serum of male subjects with conduct disorder and prisoners with history of violence. Healthy blood donors served as control subjects. RESULTS Both conduct disorder and prisoners groups displayed strongly increased levels of ACTH-reactive immunoglobulin G (IgG) and immunoglobulin M (IgM) autoAbs compared with control subjects. Levels of oxytocin-reactive IgM autoAbs were slightly increased in both groups of aggressive subjects, whereas levels of vasopressin-reactive IgG and IgM autoAbs were lower only in conduct disorder. No differences in the levels of alpha-MSH-reactive autoAbs were found between aggressive and control subjects. CONCLUSIONS High levels of ACTH-reactive autoAbs as well as altered levels of oxytocin- and vasopressin-reactive autoAbs found in aggressive subjects may interfere with the neuroendocrine mechanisms of stress and motivated behavior. Our data suggest a new biological mechanism of human aggressive behavior that involves autoAbs directed against several stress-related neurohormones.

T‐Cell Stimulation Induced by Idiotypes on Monoclonal Immunoglobulins in Patients with Monoclonal Gammopathies

The stimulation of peripheral blood mononuclear cells by purified autologous and/or allogeneic monoclonal IgG was studied in five patients with multiple myeloma (MM), nine patients with monoclonal gammopathy of undetermined significance (MGUS) and six healthy individuals.

Polymorphism in tumor necrosis factor genes associated with myasthenia gravis

The aim of this study was to analyze associations between myasthenia gravis (MG) and polymorphisms in the tumor necrosis factor (TNF) region in 79 Swedish patients and 155 unrelated controls. The frequency of the TNFa2 allele of a microsatellite located 3.5 kb upstream of the lymphotoxin alpha (LT-alpha) gene in the TNF region was found to be increased in overall MG patients compared to controls. The frequency of the short 5.5 kb fragment (TNFB * 1) of a bi-allelic NcoI RFLP polymorphism located at the first intron of the LT-alpha gene was increased in patients with an early onset of disease compared to patients with a later onset.

Anti-idiotypic antibodies in patients with monoclonal gammopathies: relation to the tumour load

Summary The production of anti‐idiotypic antibodies from Epstein‐Barr virus transformed peripheral blood lymphocytes was analysed in 12 patients with multiple myeloma and monoclonal gammopathy of undetermined significance. A low anti‐idiotype production was found in patients with advanced disease (multiple myeloma stage III), whereas the production was high in patients with multiple myeloma stage I and monoclonal gammopathy of undetermined significance (MGUS) (P<0·01). The study supports the existence of an immunological network response in patients with monoclonal gammopathies.

T and B lymphocytes reacting with the extracellular loop of the β2-adrenergic receptor (β2AR) are present in the peripheral blood of patients with myasthenia gravis

Eighteen percent of patients with myasthenia gravis (MG) have serum antibodies against a synthetic peptide corresponding to the second extracellular loop of the human β2AR (residues 172–197). In this study we examined T and B cell responses to the peptide, using assays to detect individual cells secreting interferon‐gamma (IFN‐γ) and IL‐4 or antibodies against the peptide, and by measuring thymidine incorporation in response to the peptide. The peptide from the β2AR induced cytokine secretion from blood mononuclear cells in 67% of MG patients, compared with 14–28% of the control groups. Cells secreting antibodies binding to the peptide were present in 54% of MG patients and in 19–28% of controls. The numbers of β2AR‐reactive cells were higher in MG patients than in controls. Peptide‐induced increase in thymidine incorporation in cells was also more frequently demonstrated in patients (26%) compared with controls (about 10%). Activation of cells was dependent on monocytes and on MHC class II DR antigen. Based on the pattern of the cytokine secretion induced, β2AR‐reactive T cells comprise both T helper type‐1 and type‐2 subsets. In addition, control peptide‐reactive T and B cells were much less frequently demonstrated in the patients, and the number of such cells did not differ between the groups. Our results show that β2AR‐reactive cells are present in most patients with MG. Such autoreactive antibodies and cells might play a role in the pathogenesis of the disease by influencing the function of skeletal muscle and immune systems.

T-cell epitopes on the human acetylcholine receptor α-subunit residues 10-84 in myasthenia gravis

In myasthenia gravis the production of anti‐acetylcholine receptor antibodies is modulated by acetylcholine receptor‐specific T cells. Most B‐and T‐cell epitopes are located on the α‐subunit of the receptor. In order to map the fine specificity of the antigen‐specific T cells in myasthenia gravis, T‐cell stimulation in response to 70 hexapeptides was studied in 24 patients and 24 healthy individuals. The hexapeptides overlapped with one amino acid and represented residues 10‐84 of the NH2‐terminal part of the α‐subunit of the receptor. The IFN‐γ secretion from single T cells was used to detect T‐cell stimulation.

Presynaptic Membrane Receptor‐Reactive T Lymphocytes in Myasthenia Gravis

The majority of patients with myasthenia gravis were shown to have T and Bcells specific for a β‐bungarotoxin binding protein, presynaptic membranereceptor (PsmR). Such autoreactive T cells may be subdivided into differentsubsets according to the pattern of cytokine production. In this study theauthors examined the subpopulation of the T cells by analysing their IFN‐γand/or IL‐4 secretion pattern. T cell response to human muscle acetylcholinereceptor (AChR) was examined in parallel. PsmR‐stimulated IFN‐γ secretionwas found in 60%, and IL‐4 secretion in 48% of the patients. Cells stimulated tosecrete both IFN‐γ and IL‐4 or IFN‐γ only were the most common patterns.Treatment of the cells with a mouse anti‐human HLA‐DR antibody abolished thesecretion of cytokines. There was a positive correlation between the numbers ofPsmR‐reactive and AChR‐reactive T cells. In conclusion, the results show thatPsmR‐stimulated T cells secreted IFN‐γ and/or IL‐4. This T cell response isMHC class II restricted. Thus, this study indicates that both Th1/Th2 or Th0subsets of the T cells are involved in the autoimmune response in thedisease.

ANTI-IDIOTYPIC T CELLS IN EARLY STAGES OF MYASTHENIA GRAVIS : INCREASE IN THE NUMBER AND PREVALENCE CORRELATED TO CLINICAL IMPROVEMENT IN PATIENTS

An idiotypic network involving T and B cells bearing complementary structures has been suggested to be important for the regulation of immune response in healthy and disease situations. A previous study by the authors has demonstrated the presence of a relatively higher concentration of anti‐idiotypic antibodies than of idiotypic antibodies in early myasthenia gravis (MG), suggesting that the development of an anti‐idiotypic immunity is important in early MG. The present study was conducted to examine the cellular components of the idiotypic network in the same situation. T and B cells reactive to acetylcholine receptor (AChR) or to a disease‐related idiotype and to an anti‐idiotype were analysed in seven patients with early MG at various times after the start of the disease. The results show that a significant increase in the number of idiotype‐reactive interferon‐γ‐secreting T cells and a shift from AChR‐reactive to idiotype‐ and/or anti‐idiotype‐reactive T cells in the patients at 6 month follow‐up were noted. Such changes seem to correlate to a clinical improvement in the patients. The enhanced anti‐idiotypic T‐cell response and the clinical improvement in the patients may speak in favour of a role for the anti‐idiotypic immunity in controlling the autoimmune response in MG, i.e., down‐regulating autoantibody‐producing B cells and idiotypic (AChR‐specific) T cells. Thus, an immune intervention towards the enhancement of the anti‐idiotypic immunity in patients might be a rewarding approach. Further studies with regard to cell interactions and immune regulations in the network are warranted.