T cell repertoire in patients with multiple myeloma and monoclonal gammopathy of undetermined significance: clonal CD8+ T cell expansions are found preferentially in patients with a low tumor burden

The T cell receptor (TCR) variable (V) gene repertoire was analyzed in patients with monoclonal gammopathy of undetermined significance (MGUS) (n = 17), multiple myeloma (MM) stage I (n = 16), MM stages II/III (n = 31) and age-matched controls (n = 27) by immunofluorescence and flow cytometry using a panel of mouse monoclonal antibodies (mAb) (n = 10) against TCR V alpha and V beta gene products. T cell expansion was defined as a value > or = thrice the normal median value for each respective TCR V mAb. Fifty-three percent of all patients displayed CD8+ expansion(s) as compared to 30% of age-matched controls (p < 0.001). Within the CD4 subset, 18% of the patients displayed T cell expansion(s) in comparison to 11% of the controls (not significant). Interestingly, the CD8+ expansion(s) were more frequently noted in patients with a low tumor burden (MGUS/MMI) (73%) as compared to those with advanced disease (MM II/III) (32% and control donors (30%) (p < 0.01). Likewise, multiple CD8+ expansions (two or more) were more common in MGUS/MM I patients than in MM II/III and controls (p < 0.01). The T cell expansions were stable over time in patients with a stable disease. A high degree of clonality of the expansions was detected by TCR CDR3 fragment length analysis, determination of J beta gene usage and nucleotide sequencing. The frequent finding of oligoclonal CD8+ T cell expansions in patients with a low tumor mass, but not in patients with advanced disease justifies further work in order to identify the relevance of expanded CD8+ T cells. In one patient with T cell reactivity against the autologous myeloma idiotype, two expansions within the CD8 population (V beta 3 and V beta 5.2 respectively) displayed no reactivity against the idiotype. Instead, idiotype recognition was confined to a CD8 non-expanded V beta 22+ T cell population, with a highly restricted TCR usage (CDR3 fragment length analysis).

Predisposition to gastric dilatation-volvulus in relation to genetics of thoracic conformation in Irish setters

Thoracic depth/width ratios (TDWRs) were calculated from measurements of the parents (i.e., common dam and two sires) and puppies in two litters of Irish setters. The TDWRs of the parents, distribution of TDWRs in the litters, and comparisons with earlier population studies suggest that an incompletely dominant major gene and a background of minor genes and environmental factors are responsible for the TDWR. A history of gastric dilatation-volvulus (GDV) (i.e., bloat) was correlated with high TDWRs in this family as it was for Irish setters and certain other breeds studied earlier. It may be possible to reduce the incidence of GDV by selective breeding of dogs with lower TDWRs.

Decreased beta2-adrenergic receptor density on peripheral blood mononuclear cells in myasthenia gravis

Beta2-adrenergic receptors (beta2AR) are present on both lymphocytes and skeletal muscle cells. Antibodies and T cells that react with these receptors are present in patients with myasthenia gravis (MG). Immune reactivity against the beta2AR may thus modify both the immune and the muscle functions in MG. In this study, we analysed the density and affinity of beta2AR on peripheral blood mononuclear cells using a radioligand binding assay. The density (Bmax) of the receptor on cells from patients with MG was significantly lower than that on cells from patients with other neurological disorders and healthy individuals. The affinity (Kd) of the receptor and the concentration of the second messenger, cAMP, in the cells did not differ between the groups. Serum antibodies against beta2AR were demonstrated in 22% of 27 MG patients vs. 0% of 26 healthy controls. Incubation of cells with serum or purified IgG containing antibodies against the beta2AR resulted in a decline in ligand binding of the receptor in samples from three out of five patients. Thus, this study suggests that a downregulation of the beta2AR may occur in MG. This downregulation might be of importance in the patho-genesis of the disease and its symptoms.

Current and future therapies for myasthenia gravis

Myasthenia gravis (MG) is undoubtedly the most thoroughly understood of all human autoimmune diseases. The basic defect in the disease is a decrease in the number of available acetylcholine receptors (AChR) at neuromuscular junctions caused by an antibody-mediated autoimmune attack. Current treatments aimed at restoring the available AChR, depleting the autoantibodies or suppressing the immune system have been so effective that most patients can lead normal lives. However, prolonged drug treatment is required, and this carries a potential risk of drug toxicity and, in the case of immunosuppressants, systemic immunosuppression. The ideal treatment for MG would eliminate only the abnormal autoimmune response without interfering with the immune system. During the past 20 years, impressive advances have been made in our understanding of the immunology and molecular biology of MG. Accordingly, it should be possible to design rational and immune-based therapies in the future. In this article, we briefly review the current treatment modalities for MG, and discuss the prospects for immunotherapy.

[The application of artificial neural network method in diagnose and classify research on functional disease of the esophagus]

This paper applied a typical artificial neural network model, that is Back-Propagation Model, to the diagnose and classify research on functional disease of the esophagus, and achieved good results in clinical practice.

The effect of thymectomy on autoreactive T- and B-lymphocytes in myasthenia gravis

Eleven patients with myasthenia gravis were followed for three years after thymectomy. Acetylcholine receptor-specific T-cell stimulation was found in 8/11 patients before operation as compared to 2/11 three years after thymectomy. Changes of T-cell antireceptor-reactivity were commonly paralleled by changes in disease severity. The numbers of cells secreting IL-2 upon stimulation with human acetylcholine receptor correlated with those secreting IFN-gamma. T-cell reactivity against a monoclonal acetylcholine receptor antibody did not decrease after thymectomy. Such reactivity could reflect a beneficial immune response counteracting anti-receptor reactivity. The frequency of autoantibody-secreting cells remained unchanged, while the serum concentration of acetylcholine receptor antibodies started to decrease one year after thymectomy. All examined thymus-cell suspensions contained autoreactive T- and B-lymphocytes. There was a preferential enrichment of autoreactive lymphocytes in the thymus in a few patients with recent onset of disease.

Kinetics of folding of the IgG binding domain of peptostreptococcal protein L

The kinetics of folding of a tryptophan containing mutant of the IgG binding domain of protein L were characterized using stopped-flow circular dichroism, stopped-flow fluorescence, and HD exchange coupled with high-resolution mass spectrometry. Both the thermodynamics and kinetics of folding fit well to a simple two-state model: (1) Guanidine induced equilibrium denaturation transitions measured by fluorescence and circular dichroism were virtually superimposable. (2) The kinetics of folding/unfolding were single exponential under all conditions examined, and the rate constants obtained using all probes were similar. (3) Mass spectra from pulsed HD exchange refolding experiments showed that a species with very little protection from exchange is converted to a fully protected species (the native state) at a rate very similar to that of the overall change in tryptophan fluorescence; no intervening partially protected species were observed. (4) Rate constants (in H2O) and m values for folding and unfolding determined by fitting observed relaxation rates obtained over a broad range of denaturant concentrations to a two-state model were consistent with the equilibrium parameters deltaG and m: -RT ln(k(u)/k(f))/deltaG(U)H2O = 1.02; (m(u) + m(f))/m = 1.08. In contrast to results with a number of other proteins, there was no deviation from linearity in plots of ln k(obs) versus guanidine at low guanidine concentrations, both in the presence and absence of 0.4 M Na2SO4, suggesting that significantly stabilized intermediates do not accumulate during folding. Although all of the change in fluorescence signal during folding in phosphate buffer was accounted for by the simple exponential describing the overall folding reaction, fluorescence-quenching experiments using sodium iodide revealed a small reduction in the extent of quenching of the protein within the first two milliseconds after initiation of refolding in low concentrations of guanidine, suggesting a partial collapse of the unfolded chain may occur under these conditions. Comparison with results on the structurally and functionally similar IgG binding domain of streptococcal protein G show intriguing differences in the folding of the two proteins.

Idiotype-specific T lymphocytes in monoclonal gammopathies: evidence for the presence of CD4+ and CD8+ subsets

Tumour-specific CD4+ T helper (Th) and CD8+ T cytotoxic (Tc) cells may participate in the control and eradication of tumour cells. In the present study, idiotype-specific stimulation of CD4+ and CD8+ blood T cells from patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma stage I was examined. Activation was measured in the CD4+ and CD8+ subsets enriched by magnetic microbeads as the incorporation of 3H-thymidine and the secretion of interferon (IFN)-gamma, interleukin (IL)-2 and IL-4 by single cells using the enzyme-linked immunospot assay. Idiotype-specific T cells were found in four of seven patients. Stimulation was mainly confined to the CD4+ subset in three of the four responding patients. This type of response was major histocompatibility complex (MHC) class II restricted as it could be inhibited by monoclonal antibodies against MHC class II (HLA-DR), but not against class I (HLA-ABC) molecules. Idiotype-specific CD8+ T cells were also demonstrated in these patients although at a lower frequency. One patient showed a strong and dominating activation of CD8+ T cells which could be blocked by antibodies against HLA-ABC but not against HLA-DR. Idiotype-specific CD4+ or CD8+ T cells were mainly of the type-1 subsets as judged by their secretion of IFN-gamma and IL-2. Thus, this study provides evidence for the presence of idiotype-specific and MHC-restricted CD4+ and CD8+ T cells of the type-1 subsets in patients with monoclonal gammopathies. Such T cells with the potential to control the growth of tumour B cells may be a suitable target for immunotherapeutic interventions in patients.

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 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-gamma-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.

p53 expression in uveal malignant melanomas

Mutation of the p53 gene which is located on chromosome 17p is the single most frequent alteration observed in human cancer. In this study we evaluate malignant melanoma, the most common intraocular neoplasm in adults, for aberrant p53 expression. Twenty enucleation specimens representing one ciliary body and 17 choroidal melanomas and two choroidal nevi were studied by immunohistochemistry utilizing the D07 anti-p53 antibody and the MIB-1 monoclonal antibody. The tumors included two spindle cell and 16 mixed cell (spindle + epithelioid cell) melanomas and two spindle cell nevi. The MIB-1 labelling index ranged from < 1% (two cases), 1-5% (13 cases) and > 5% (five cases). Of the 18 melanomas, 13 cases showed nuclear p53 staining with the p53 index < 1% (two cases), 1-3% (eight cases) and 4-5% (three cases). No p53 staining was observed in two malignant melanomas of the spindle cell type and in two choroidal nevi. In the 13 malignant melanomas of the mixed cell type, there was no correlation between MIB-1 index and p53 immunoreactivity. Immunopositivity was not found in normal choroidal melanocytes. Our study suggests that p53 alterations may be found in uveal melanomas; in our series, p53 positivity was present only in malignant melanomas of the mixed cell type.

Direct evidence for a two-state protein unfolding transition from hydrogen-deuterium exchange, mass spectrometry, and NMR

We use mass spectrometry in conjunction with hydrogen-deuterium exchange and NMR to characterize the conformational dynamics of the 62-residue IgG binding domain of protein L under conditions in which the native state is marginally stable. Mass spectra of protein L after short incubations in D2O reveal the presence of two distinct populations containing different numbers of protected protons. NMR experiments indicate that protons in the hydrophobic core are protected in one population, whereas all protons are exchanged for deuterons in the other. As the exchange period is increased, molecules are transferred from the former population to the latter. The absence of molecules with a subset of the core protons protected suggests that exchange occurs in part via a highly concerted transition to an excited state in which all protons exchange rapidly with deuterons. A steady increase in the molecular weight of the population with protected protons, and variation in the exchange rates of the individual protected protons indicates the presence of an additional exchange mechanism. A simple model in which exchange results from rapid (> 10(5)/s) local fluctuations around the native state superimposed upon transitions to an unfolded excited state at approximately 0.06/s is supported by qualitative agreement between the observed mass spectra and the mass spectra simulated according to the model using NMR-derived estimates of the proton exchange rates.

Idiotype-induced T cell stimulation requires antigen presentation in association with HLA-DR molecules

An important and yet unresolved question concerns the mode of T cell recognition of idiotypic epitopes on immunoglobulin molecules in humans. Results from murine and human studies show that some idiotype-specific T cells recognize conformational epitopes on immunoglobulin, and such T cells are not MHC-restricted. In the present study T cell stimulation induced by idiotypic determinants on the autologous monoclonal IgG (M-components) from patients with monoclonal gammopathies was studied. In parallel, T cell stimulation in response to a conventional antigen, purified protein derivative, was also examined. It is shown that, as with conventional antigen, idiotype-induced T cell stimulation requires the presence of antigen-presenting cells (APC; monocytes and/or B cells), and is MHC class II (DR)-restricted. B cells, but not monocytes, can present idiotypic determinants to T cells at very low antigen concentrations, while monocytes do so only when antigen is present at high concentrations. Antigen processing and presentation is abrogated by treatment of APC with chloroquine. In conclusion, our study demonstrates that human idiotype-specific T cells recognize processed idiotypic determinants presented by MHC class II (HLA-DR) molecules on APC, and that B cells require about 1000-fold less antigen that monocytes.

Expression of bcl-2 in uveal malignant melanoma

OBJECTIVE

To evaluate the expression of the bcl-2 proto-oncogene in uveal malignant melanomas.

CASE MATERIAL

We studied 20 uveal malignant melanomas (19 choroidal and 1 ciliary body) by immunohistochemistry with the bcl-2 oncoprotein monoclonal antibody and the cell proliferation marker, MIB-1.

RESULTS

Expression of bcl-2 was found in 100% of cases and was not correlated with the histologic subtype of melanoma or the MIB-1 proliferative index. Normal choroidal melanocytes were negative for bcl-2.

CONCLUSION

Our results suggest that altered expression of bcl-2 is common in uveal melanomas and is not related to histologic grade.

Modulation of anti-idiotypic immune response by immunization with the autologous M-component protein in multiple myeloma patients

Multiple myeloma is characterized by a proliferation of clonal B lymphocytes and plasma cells. The idiotypic structure of clonal immunoglobulin (Ig) expressed on the tumour B-cell surface can be regarded as a tumour-specific antigen and, as such, a potential target for anti-idiotypic T and B-cells in an immune regulation of the tumour-cell clone. Active immunization using the autologous mono-clonal Ig as a 'vaccine' was shown to induce tumour-specific immunity in murine B-cell tumours and in human B-cell lymphoma. With the aim to induce or amplify an anti-idiotypic response in multiple myeloma, five stage I-III patients were repeatedly immunized with the autologous monoclonal IgG. Induction of idiotype-specific cellular immunity was analysed in vitro by an enzyme-linked immunospot assay (interferon-gamma and interleukin-4 secreting cells). B cells secreting anti-idiotypic IgM antibodies were also analysed. An anti-idiotypic T-cell response was amplified 1.9-5-fold in three of the five patients during immunization. The number of B cells secreting anti-idiotypic antibodies also increased in these three patients. In two of the patients induction of idiotype-specific immunity was associated with a gradual decrease of blood CD19+ B cells. The induced T-cell response was eliminated during repeated immunization. Further studies are warranted to optimize the immunization schedule in order to achieve a long-lasting T-cell immunity against idiotypic determinants on the tumour clone. A role for immunity in controlling the tumour clone remains to be established.

Idiotype-specific T cells in multiple myeloma: targets for an immunotherapeutic intervention?

In this paper, the results of some recent studies on idiotype-specific T cells in human multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) are discussed. By using different in vitro measurements such as 3H-thymidine incorporation and ELI-SPOT assay, idiotype-specific T cells have been demonstrated in most of MM and MGUS patients. Based on the cytokine-secretion profiles, idiotype-specific T cells were found to comprise both Th1 and Th2 cells. A Th1 type immunity was found preferentially in indolent disease and a Th2-like response predominated in advanced MM, suggesting a specific T-cell regulation of the tumor B-cell clone. The mode of T-cell recognition of id determinants on M-components has been studied. We found that idiotype-specific T cells recognized processed id determinants presented by MHC class II (HLA-DR) molecules on APC. B cells were much more efficient APC than monocytes. With the aim to induce or to amplify an idiotype-specific T-cell response, we have immunized MM patients with the autologous M-component precipitated in aluminum. Three out of the five patients showed an induction of specific cellular and humoral immunity. Nevertheless, the role for such immunity in controlling the tumor clone remains to be established.

The survival analyses of 2738 patients with simple pneumoconiosis

OBJECTIVES

To explore whether the inhalation of coal mine dust increases the risk of premature death in miners, a survival analysis was conducted in a cohort of 2738 patients with simple pneumoconiosis in the Huai-Bei coal mine, in China.

METHODS

Age specific mortalities were calculated by disease severity in terms of pneumoconiotic category with the life table method. The progressions from simple pneumoconiosis to death or progressive massive fibrosis (PMF) were analysed with the Cox's regression model with time as the dependent variable to identify risk factors.

RESULTS

During a follow up period (mean 8 y) 3.2% of patients with simple pneumoconiosis developed PMF. The patients with development of PMF presented higher age specific mortalities than those remaining in a state of simple pneumoconiosis (SMR: 3.42; P < 0.01). After adjustment for tuberculosis and duration of work, the relative risk of premature death due to development of PMF was 2.4. Tuberculosis was found to be a main risk factor which not only facilitated premature death (relative risk (RR): 2.0; P < 0.01), but was also a strong facilitator for development of PMF (RR: 7.0; P < 0.01). Also, a long term of work underground and drilling as a main job were identified as risk factors for development of PMF.

CONCLUSION

The results imply that patients with simple pneumoconiosis will have altered survival, and premature death among them is related to an increased risk of the development of PMF and the complication of tuberculosis.

Presynaptic membrane receptor-reactive T lymphocytes in myasthenia gravis

The majority of patients with myasthenia gravis were shown to have T and B cells specific for a beta-bungarotoxin binding protein, presynaptic membrane receptor (PsmR). Such autoreactive T cells may be subdivided into different subsets according to the pattern of cytokine production. In this study the authors examined the subpopulation of the T cells by analysing their IFN-gamma and/or IL-4 secretion pattern. T cell response to human muscle acetylcholine receptor (AChR) was examined in parallel. PsmR-stimulated IFN-gamma secretion was found in 60%, and IL-4 secretion in 48% of the patients. Cells stimulated to secrete both IFN-gamma and IL-4 or IFN-gamma only were the most common patterns. Treatment of the cells with a mouse anti-human HLA-DR antibody abolished the secretion of cytokines. There was a positive correlation between the numbers of PsmR-reactive and AChR-reactive T cells. In conclusion, the results show that PsmR-stimulated T cells secreted IFN-gamma and/or IL-4. This T cell response is MHC class II restricted. Thus, this study indicates that both Th1/Th2 or Th0 subsets of the T cells are involved in the autoimmune response in the disease.

T and B lymphocytes reacting with the extracellular loop of the beta 2-adrenergic receptor (beta 2AR) 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 beta 2AR (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-gamma) and IL-4 or antibodies against the peptide, and by measuring thymidine incorporation in response to the peptide. The peptide from the beta 2AR 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 beta 2AR-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, beta 2AR-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 beta 2AR-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.

Idiotype-reactive T-cell subsets and tumor load in monoclonal gammopathies

The presence of idiotype-reactive T-cell subsets and their relation to the tumor load were analyzed in 9 patients with monoclonal gammopathy of undetermined significance (MGUS), in 12 patients with multiple myeloma (MM) clinical stage I, and in 9 patients with MM stage II/III. An enzyme-linked immunospot assay was used to identify interferon-gamma (IFN-gamma)-, interleukin-2 (IL-2)-, or IL-4-secreting T cells after stimulation by F(ab')2 fragments of monoclonal IgG. The response to autologous IgG was significantly higher than that induced by isotypic monoclonal IgG. Comparable results were obtained in a proliferation assay (3H-thymidine incorporation). A total of 8 of 9 patients with MGUS, 7 of 12 patients with MM stage I, and 3 of 9 with MM stage II/III had T cells secreting IFN-gamma and/or IL-2 (T helper [Th1] type-1 cells), whereas cells secreting both Th1 and Th2 or Th0 types of cytokines were more frequent in patients with MM, particularly in those with MM stage II/III. The number and frequency of Th1-type cells were significantly higher in MGUS patients as compared with those of MM stage II/III. The results indicate that idiotype-reactive T cells of the Th1 and Th2 or Th0 subsets were present in MGs and might provide indirect evidence that idiotype-reactive Th1-type cells may have a regulatory impact on the human tumor B cells.

Computer simulation analysis of Sartwell's incubation period model for diseases with uncertain etiology. The effect of competing risk

Computer simulation was applied to Sartwell's model to examine the impact of competing risks of death on the underlying assumptions and the power to reject both uniform and normal incubation period distributions. Exponential and nonparametric survival functions were imposed onto lognormal, uniform, and normal distributions to create random samples reflecting competing risk. These random samples were evaluated with the Shapiro-Wilk's test to determine the proportion for which the lognormal distribution was rejected. The simulations indicated that competing causes of death do not significantly alter the lognormal distribution of incubation periods. In only approximately 5% of the samples drawn from a lognormal distribution was a lognormal hypothesis rejected with a goodness-of-fit test when sample size varied from 20 to 500. There was generally good power (> 80%) to reject a lognormal distribution if the random samples were generated from a uniform distribution of incubation times, but not when they were generated from a normal distribution, particularly with increasing ages at disease onset. Varying the standard deviation did not significantly change the simulation results if the random samples came from a lognormal or uniform distribution. These conclusions were further supported by application of Sartwell's model to published data on the ages of onset for several chronic diseases.

A phage display system for studying the sequence determinants of protein folding

We have developed a phage display system that provides a means to select variants of the IgG binding domain of peptostreptococcal protein L that fold from large combinatorial libraries. The premise underlying the selection scheme is that binding of protein L to IgG requires that the protein be properly folded. Using a combination of molecular biological and biophysical methods, we show that this assumption is valid. First, the phage selection procedure strongly selects against a point mutation in protein L that disrupts folding but is not in the IgG binding interface. Second, variants recovered from a library in which the first third of protein L was randomized are properly folded. The degree of sequence variation in the selected population is striking: the variants have as many as nine substitutions in the 14 residues that were mutagenized. The approach provides a selection for "foldedness" that is potentially applicable to any small binding protein.

[Study on the lung targeting gelatin microspheres of streptomycin sulphate]

This paper is reported the technology of lung targeting gelatin microspheres of streptomycin sulphate (SMS). The microspheres were prepared with natural biodegradable gelatin as the load material and castor oil as the oil phase. The experimental conditions were optimized, the mean volume diameter obtained being 9.7 microns and the mean rate of encapsulation 15.69%. The content, shape and size of the microspheres showed no remarkable change after storage at 37 degrees C RH 75% for 3 months. Activation energy of heat decomposition E = 75.86kJ/mol. In vitro, the SMS release rate was found to accord with Higuchi equation with t1/2 = 8.6h. In vivo (rabbits) the gelatin microspheres were proved to be concentrated in the lung.

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.

Carbachol-stimulated phosphorylation of the Na-K-Cl cotransporter of avian salt gland. Requirement for Ca2+ and PKC Activation

The Na-K-Cl cotransporter of avian salt gland is a membrane-bound 170-kDa protein that is phosphorylated in response to cAMP- and Ca(2+)-dependent secretogogues and is homologous to the Na-K-Cl cotransporter in another Cl-secreting epithelia; the shark rectal gland (Torchia, J., Lytle, C., Pon, D. J., Forbush, B., and Sen, A. K. (1992) J. Biol. Chem. 267, 25444-25450). In the present study we assess the role of Ca2+ and protein kinase C (PKC) activation on the phosphorylation of the Na-K-Cl cotransporter. Although the addition of ionomycin alone did not significantly stimulate cotransporter phosphorylation, concurrent addition of ionomycin plus the tumor promoter phorbol 12-myristate 13-acetate (PMA) resulted in a concentration-dependent increase in phosphorylation. Immunoprecipitation experiments, using a monoclonal antibody which specifically recognizes the cotransporter, suggested that the response to CCh or ionomycin plus PMA was quantitatively similar (5-fold) and was localized exclusively on serine residues. In contrast, when 4 alpha-phorbol was added in the presence of ionomycin, no stimulation was observed. To further assess the involvement of PKC on cotransporter phosphorylation the effects of protein kinase inhibitors were tested. Both staurosporine and calphostin C inhibited phosphorylation of the cotransporter at concentrations known to inhibit PKC, whereas the calmodulin antagonist W-7 had no significant effect. The requirement for Ca2+ was tested further by removing Ca2+ from the incubation medium and stimulating with CCh. Under these conditions, the CCh-stimulated phosphorylation was transient and, furthermore, could be completely inhibited by preloading the cells with the Ca2+ chelator BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid) prior to stimulation. The involvement of protein phosphatases on the phosphorylation of the Na-K-Cl cotransporter was also tested. The addition of okadaic acid stimulated phosphorylation by approximately 3-fold. Taken together these results suggest that the phosphorylation state of the cotransporter involves a dynamic interplay between changes in intracellular Ca2+, PKC, and protein phosphatase activities.

Studies of protein-protein association between yeast cytochrome c peroxidase and yeast iso-1 ferricytochrome c by hydrogen-deuterium exchange labeling and proton NMR spectroscopy

Hydrogen-deuterium (H-D) exchange labeling and proton NMR have been applied to study the protein-protein association between cytochrome c peroxidase (CcP) and yeast iso-1 ferricytochrome c. Specifically, the exchange behavior of individual backbone amide protons of yeast iso-1 ferricytochrome c in both CcP-bound (i.e., complexed) and free (i.e., never in the complex) forms has been investigated and used in an attempt to map the binding site of CcP on yeast iso-1 ferricytochrome c when the noncovalent complex was formed in very low salt solution. The exchange rates of certain amino acid amide protons were significantly slowed down, by up to 40-fold, in the complex compared to the free form. The protected regions on iso-1 ferricytochrome c include parts of the 10's helix and the 70's helix surrounding the cytochrome c heme solvent-exposed edge (the so-called "front side" of iso-1 cytochrome c). These regions are very similar to the cytochrome c peroxidase binding interface on iso-1 ferricytochrome c that has been defined by X-ray crystallographic data. This further supports the direct involvement of the front side of iso-1 cytochrome c in binding with cytochrome c peroxidase. The results from our H-D exchange experiments also indicated that the amide proton exchange rates of Trp59, Asp60, and part of the 90's helix, all of which are located on the opposite side (the "back" side) of ferricytochrome c from the heme solvent-exposed edge, are also retarded upon complex formation.

Idiotype- and anti-idiotype-reactive T lymphocytes in myasthenia gravis. Evidence for the involvement of different subpopulations of T helper lymphocytes

Patients with myasthenia gravis have peripheral blood T cells that are stimulated to secrete IFN-gamma and IL-2 by human monoclonal anti-acetylcholine receptor and anti-idiotypic Abs. The human CD4+ Th cells may be subdivided into different subsets according to the pattern of cytokine production. To elucidate the subgroup of T cells involved in myasthenia gravis, we have analyzed IL-4-, IFN-gamma-, and IL-2-secretion patterns induced by two human disease-specific mAbs, one idiotypic and one anti-idiotypic Ab. T cells stimulated to secrete one or more of the cytokines were found in 33 of 34 patients. The idiotypic Ab stimulated IL-4 secretion in 19 of 34 patients, IFN-gamma secretion in 26 of 34 patients, and IL-2 secretion in 25 of 34. The anti-idiotypic Ab induced IL-4 secretion in 9 of 34 patients, IFN-gamma secretion in 29 of 34 patients, and IL-2 secretion in 28 of 34 patients. These T cell responses were MHC class II-restricted. According to the cytokine-secretion patterns, Id-reactive T cells might correspond to both Th1/Th2 and/or Th0 cells. The anti-idiotypic Ab more frequently induced a Th1-type response. This study indicates that different subsets of T lymphocytes are involved in the idiotypic network in myasthenia gravis, and that these functionally different T cells may participate in the immunoregulation of the disease.

Idiotype- and anti-idiotype-reactive T lymphocytes in myasthenia gravis. Evidence for the involvement of different subpopulations of T helper lymphocytes

Patients with myasthenia gravis have peripheral blood T cells that are stimulated to secrete IFN-gamma and IL-2 by human monoclonal anti-acetylcholine receptor and anti-idiotypic Abs. The human CD4+ Th cells may be subdivided into different subsets according to the pattern of cytokine production. To elucidate the subgroup of T cells involved in myasthenia gravis, we have analyzed IL-4-, IFN-gamma-, and IL-2-secretion patterns induced by two human disease-specific mAbs, one idiotypic and one anti-idiotypic Ab. T cells stimulated to secrete one or more of the cytokines were found in 33 of 34 patients. The idiotypic Ab stimulated IL-4 secretion in 19 of 34 patients, IFN-gamma secretion in 26 of 34 patients, and IL-2 secretion in 25 of 34. The anti-idiotypic Ab induced IL-4 secretion in 9 of 34 patients, IFN-gamma secretion in 29 of 34 patients, and IL-2 secretion in 28 of 34 patients. These T cell responses were MHC class II-restricted. According to the cytokine-secretion patterns, Id-reactive T cells might correspond to both Th1/Th2 and/or Th0 cells. The anti-idiotypic Ab more frequently induced a Th1-type response. This study indicates that different subsets of T lymphocytes are involved in the idiotypic network in myasthenia gravis, and that these functionally different T cells may participate in the immunoregulation of the disease.

Treatment of myasthenia gravis with anti-CD4 antibody: improvement correlates to decreased T-cell autoreactivity

We treated a patient with severe myasthenia gravis with a chimeric (murine/human) anti-CD4 monoclonal antibody (cM-T412) for 7 days and followed the therapeutic effect by standardized muscle function tests, single-fiber electromyography, and immunologic examinations of disease-specific B- and T-cell functions. Clinical and electrophysiologic improvement began within 4 days, lasted for 3 months, and was maximal between days 16 and 58. The CD4+ lymphocytes decreased to a minimum of 80 cells per microliters of peripheral blood, recovered slowly during the first year of follow-up, and did not correlate with changes in disease severity. T-cell stimulation by human acetylcholine receptor was abolished by the treatment but became detectable at the time of worsening of symptoms. The concentration of acetylcholine receptor antibodies in serum was not decreased by the treatment. The results suggest that anti-CD4 antibody administration could be effective in the treatment of severe myasthenia gravis and indicate that acetylcholine receptor-specific T lymphocytes might contribute to the disturbed neuromuscular transmission in the disease.

Anti-idiotypic B lymphocytes in patients with monoclonal gammopathies

The prevalence of peripheral blood B cells secreting antibodies reacting with the F(ab')2 fragment of monoclonal IgG was studied in five patients with multiple myeloma (MM), nine patients with monoclonal gammopathy of undetermined significance (MGUS) and six healthy controls. An enzyme-linked immunospot assay allowed direct visualization of antibody producing B cells. All patients had B cells producing antibodies to autologous or allogeneic monoclonal IgG. Autoreactive cells were found more frequently than alloreactive cells in seven out of nine patients with MGUS and three out of four patients with MM. The same frequency of alloreactive cells in the patient groups was detected in healthy individuals. These findings show the existence of B cells producing anti-idiotypic antibodies which could be a part of an idiotypic network in monoclonal gammopathies.

Acetylcholine receptor-reactive T cells in myasthenia gravis: evidence for the involvement of different subpopulations of T helper cells

Patients with myasthenia gravis have a high prevalence of acetylcholine receptor-specific T lymphocytes in the peripheral blood. Our earlier study shows that these T lymphocytes are stimulated to secrete interferon (IFN)-gamma and interleukin (IL)-2 in response to the autoantigen. Such stimulated T cells may be subdivided into different subsets according to the pattern of cytokine production. In the present study we have investigated the subpopulations of cells by analyzing their IL-4, IFN-gamma and IL-2 secretion pattern. Autoantigen-stimulated IL-4 secretion was found in 55% of the patients, IFN-gamma secretion in 86% and IL-2 secretion in 72%. T lymphocytes from all patients who responded with increased IL-2 secretion also showed increased IFN-gamma secretion. Stimulated IL-4 secretion was detected both in the presence and absence of stimulated IFN-gamma secretion. Depletion of monocytes/macrophages from peripheral blood mononuclear cell preparation and treatment of the cells with a mouse anti-human HLA-DR antibody abolished the secretion of IFN-gamma and IL-4. There were positive correlations between the numbers of IFN-gamma- and IL-2-secreting T cells and the numbers of B cells secreting antibodies against the acetylcholine receptor. Our results show that acetylcholine receptor-stimulated T lymphocytes secrete IL-4, IFN-gamma and/or IL-2. This T cell response is major histocompatibility complex (MHC) class II-restricted and monocyte/macrophage-dependent. Our study indicates that both Th1/Th2 or Th0 subpopulations of the T lymphocytes are involved in the autoimmune response in myasthenia gravis.

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. Single cells secreting IFN-gamma or IL-2 were identified using an enzyme-linked immunospot assay. Patients' cells were preferentially stimulated by autologous monoclonal IgG at low concentrations (1-100 pg/ml), while 100 ng/ml or higher stimulated T cells both from patients and, to a lesser degree, healthy individuals. This biphasic dose-response of T-cell stimulation by autologous monoclonal IgG was reproduced in all patients. The numbers of cells secreting IFN-gamma and IL-2 in response to allogeneic IgG were significantly lower than the numbers obtained using autologous IgG in patients with MM and MGUS. Cells from healthy individuals were stimulated by allogeneic monoclonal IgG, but to a lesser extent. The results of this study support the presence of idiotype-reactive T cells in patients with MM and MGUS and also may suggest a general but less pronounced T-cell reactivity to monoclonal IgG among these patients.

Proton NMR studies of noncovalent complexes of cytochrome c peroxidase-cyanide with horse and yeast ferricytochromes c

Noncovalent complexes of cyanide-ligated cytochrome c peroxidase with horse ferricytochrome c and yeast isozyme-1 ferricytochrome c have been formed in 10 mM potassium nitrate salt solutions and studied by proton NMR spectroscopy. The chemical shifts in the ferricytochrome c spectrum induced by complex formation with low-spin, cyanide-ligated cytochrome c peroxidase are similar to the corresponding shifts induced by complex formation with resting-state cytochrome c peroxidase, found previously. As with the resting-state enzyme, the complex between yeast cytochrome c and cytochrome c peroxidase-cyanide exhibits the larger set of complex-induced shifts. Two-dimensional proton NMR spectroscopy has been used to make resonance assignments. This was necessitated due to the extensive resonance overlap between the two proteins in the hyperfine shift region, since both heme proteins in this complex are low-spin paramagnetic species. These results expand preliminary work that revealed for the first time that cytochrome c binding affected the resonances of protons in the peroxidase heme pocket [Yi, Q., Erman, J. E., & Satterlee, J. D. (1992) J. Am. Chem. Soc. 114, 7907-7909]. The pattern of cytochrome c peroxidase complex-induced shifts is largely consistent with the X-ray crystal structures of these two complexes that have recently been published.

Human muscle acetylcholine receptor reactive T and B lymphocytes in the peripheral blood of patients with myasthenia gravis

The prevalence of T and B cells reactive with the acetylcholine receptor (AChR) of human skeletal muscle was studied in 33 patients with myasthenia gravis (MG), 18 patients with other neurological diseases (OND) or autoimmune disorders (AD) and 27 age- and sex-matched healthy controls. T cell stimulation was estimated by enumerating cells secreting interferon (IFN)-gamma and interleukin (IL)-2 in response to the AChR, whereas B cell reactivity was estimated by enumerating cells secreting IgG antibodies binding to the AChR. AChR-reactive T cells were increased in the peripheral blood of patients with MG as compared to patients with OND, AD and healthy individuals. Of the patients with MG, 29/33 (87.7%) had numbers of IFN-gamma secreting cells higher than the mean +/- 2 SD of the mean of controls as compared to 4/18 (22.2%) of patients with OND or AD and 2/27 (7.4%) of the controls. The mean value of the numbers of AChR-reactive T cells in the patients with MG was 19.6/10(5) PBMC, corresponding to 1/5100 PBMC. Comparable results were obtained also for IL-2-secreting cells. Anti-AChR IgG antibody-secreting cells were detected in the blood of 30/33 (91%) of the patients with MG, 3/18 (16.7%) of the patients with OND or AD and 2/25 (8%) of the controls. The mean value of the antibody-secreting cells in MG was 11.7 cells/10(6) PBMC corresponding to 1/70,400 PBMC in the patients with MG, compared to a mean value of antibody-secreting cells in the patients with OND or AD of 0.33 and controls of 0.16 cells/10(6) PBMC.

Idiotypic and antiidiotypic T and B lymphocytes in myasthenia gravis

The prevalence of Id and anti-Id T and B cells as measured by their reactivities with two human mAb, one antiacetylcholine receptor mAb and one anti-Id mAb, was studied in 38 patients with myasthenia gravis and in 27 healthy individuals. Id and anti-Id T cells were estimated by enumerating the numbers of cells secreting IFN-gamma in response to 10 pg/ml of the human mAb. T cell stimulation, measured as numbers of IFN-gamma-secreting cells that exceeded the mean + 2 SD of controls, was induced by the Id mAb in 78.9% of the patients and in 7.4% of the controls, whereas the anti-Id mAb-stimulated T cells in 55.3% of the patients and in 3.7% of the controls. The mean value of the Id and anti-Id-reactive T cells in the patients was 18.3/10(5) and 10.1/10(5) PBMC, respectively. B cells secreting IgM antibodies binding to the human mAb were increased in patients with myasthenia gravis compared to healthy controls. Seventy-five percent of the patients and 12% of the controls had B cells secreting IgM antibodies binding to the Id mAb, although 89% of the patients and 16% of the controls had B cells secreting IgM antibodies binding to the anti-Id mAb. The mean value of B cells secreting IgM antibodies binding to Id or anti-Id mAb in the patients were 7.4 cells/10(6) and 5.5 cells/10(6) PBMC, respectively. We conclude that Id and anti-Id T and B cells are present in myasthenia gravis. These methods allow a quantitative estimation of T and B cells with defined specificities and thus a way of mapping the repertoire of lymphocytes.

Idiotypic and antiidiotypic T and B lymphocytes in myasthenia gravis

The prevalence of Id and anti-Id T and B cells as measured by their reactivities with two human mAb, one antiacetylcholine receptor mAb and one anti-Id mAb, was studied in 38 patients with myasthenia gravis and in 27 healthy individuals. Id and anti-Id T cells were estimated by enumerating the numbers of cells secreting IFN-gamma in response to 10 pg/ml of the human mAb. T cell stimulation, measured as numbers of IFN-gamma-secreting cells that exceeded the mean + 2 SD of controls, was induced by the Id mAb in 78.9% of the patients and in 7.4% of the controls, whereas the anti-Id mAb-stimulated T cells in 55.3% of the patients and in 3.7% of the controls. The mean value of the Id and anti-Id-reactive T cells in the patients was 18.3/10(5) and 10.1/10(5) PBMC, respectively. B cells secreting IgM antibodies binding to the human mAb were increased in patients with myasthenia gravis compared to healthy controls. Seventy-five percent of the patients and 12% of the controls had B cells secreting IgM antibodies binding to the Id mAb, although 89% of the patients and 16% of the controls had B cells secreting IgM antibodies binding to the anti-Id mAb. The mean value of B cells secreting IgM antibodies binding to Id or anti-Id mAb in the patients were 7.4 cells/10(6) and 5.5 cells/10(6) PBMC, respectively. We conclude that Id and anti-Id T and B cells are present in myasthenia gravis. These methods allow a quantitative estimation of T and B cells with defined specificities and thus a way of mapping the repertoire of lymphocytes.

T-cell epitopes on the human acetylcholine receptor alpha-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 alpha-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 alpha-subunit of the receptor. The IFN-gamma secretion from single T cells was used to detect T-cell stimulation. A significant difference in the T-cell response to several of the peptides was found between patients and healthy controls. The majority of the hexapeptides induced T-cell stimulation in at least one of the patients. Peptide-induced T-cell stimulation was evident in all but one of the patients. The results indicate that different epitopes and multiple T-cell clones are involved in the T-cell recognition of the acetylcholine receptor.

Levels of CD5+ B lymphocytes do not differ between patients with myasthenia gravis and healthy individuals

CD5+ B cells might be involved in autoimmunity mainly as autoantibody-producing cells. To investigate the possible role of these cells in myasthenia gravis, we studied the numbers of CD5+ B cells, CD5- B cells, and CD19+ B cells as well as CD5+ T cells in the peripheral blood from 31 patients with myasthenia gravis and 31 healthy individuals. Both absolute percentages (percent of peripheral blood mononuclear cells) and relative percentages (percent of total CD19+ B cells) of CD5+ B cells were the same in patients as in controls. The numbers of CD5- B cells and CD19+ B cells were the same in both groups, whereas CD5+ T cells were lower in the patients. There was no correlation between clinical stage, sex, thymectomy, or pathology of thymus and the levels of CD5+ B cells, CD5- B cells, or CD19+ B cells. Patients treated with azathioprine had lower levels of CD5+ B cells than untreated patients and controls. Our results show that patients with myasthenia gravis have the same levels of CD5+ B cells as healthy individuals.

T cells with specificity for idiotypic determinants on human monoclonal autoantibodies in myasthenia gravis

The activation of T cells from 46 patients with myasthenia gravis and 28 healthy individuals by two human monoclonal autoantibodies was studied. B-cell clones were produced by transformation of peripheral lymphocytes from a patient using Epstein-Barr virus and subsequent cloning. Two myasthenia-specific autoantibodies, one anti-receptor-antibody and one antiidiotypic antibody, both carrying separate recurrent idiotopes, were used in this study. Single activated T cells were identified by their secretion of IL2 and IFN gamma using a cell enzyme-linked-immunosorbent technique. The idiotypic antibody activated T cells in patients but not in most of the controls at concentrations of 1 pg/ml and 10 pg/ml. High concentrations of antibody resulted in T-cell activation in both groups. A similar dose-response pattern was recorded using the antiidiotypic antibody. Incubation with the idiotypic antibody resulted in T-cell stimulation, measured as numbers of IFN gamma-secreting cells that exceeded the mean +2 SD of controls, in 78% of patients and in 7% of the healthy individuals (p less than 0.001). The antiidiotypic antibody activated T cells in 50% of patients and in 4% of the healthy individuals (p less than 0.001). T-cell activation measured as numbers of IL2-secreting cells showed a difference between patients and controls which was as significant as for IFN gamma secretion. The results demonstrate the presence of T cells with specificity for disease-specific determinants on idiotypic and antiidiotypic antibodies in myasthenia gravis.

Anti-idiotypic immunity as a potential regulator in myeloma and related diseases

In this paper some recent and partly preliminary results on anti-idiotypic immunity against clonal B cells in human monoclonal gammopathies are summarized. B cell lines producing antibodies to idiotypic determinants on autologous monoclonal immunoglobulin could be propagated after activation with Epstein-Barr virus of peripheral blood lymphocytes from patients with MGUS and MM clinical stage I but not from untreated persons with advanced MM. Blood T lymphocytes from patients with MGUS and Waldenström's macroglobulinemia were activated to DNA synthesis and production of interleukins by the autologous M protein. In another series of experiments T cell clones raised from patients with MM clinical stage I and MGUS bound F(ab')2 fragments of the autologous M protein and were stimulated to DNA synthesis by the idiotope-bearing protein. Control experiments demonstrated the specificity for idiotypic determinants. Ten of eleven clones were CD4-/CD8+. Finally, using a panel of 8 mAbs to alpha/beta V region epitopes, we noted a clonal expansion of CD4+ and CD8+ T cells in MGUS and MM patients.

The purified Ca2+ antagonist receptor from skeletal muscle: subunit structure, photoaffinity labeling and endogenous protein kinase activity

Tritiated analogues of the Ca2+ channel blockers such as [3H] PN200-110, [3H] verapamil and [3H] diltiazem have been used to identify and isolate Ca2+ antagonist receptors. The Ca2+ antagonist binding sites were solubilized from skeletal muscle transverse tubules with the detergent CHAPS and purified by wheat germ lectin column chromatography and sucrose density gradient centrifugation. The isolated proteins retained their ability to bind the various classes of Ca2+ channel blockers. Polypeptides of 170, 150, 108, 56, and 32 kDa were found to be present in the purified receptor fraction when analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis under non-reducing conditions. The apparent molecular weight of the 170 kDa polypeptide changed to 145 kDa in the presence of reducing agents, as where the apparent molecular weight of the 150, 108, 56 and 32 kDa peptides remained unchanged. An endogenous protein-kinase present in the original membranes, co-purified with the receptor and stimulated the phosphorylation of the 150 and 56 kDa polypeptides in the isolated fraction.

Subcellular distribution and isolation of the Ca2+ antagonist receptor associated with the voltage regulated Ca2+ channel from rabbit heart muscle

The Ca2+ antagonist binding sites associated with the voltage dependent calcium channel in rabbit myocardium were found to distribute with the sarcolemmal Na+ + K+ ATPase and adenylate cyclase activities during subcellular fractionation on sucrose-density gradients. The equilibrium dissociation constants (KD) for the binding of [3H]nitrendipine and [3H]verapamil were 0.31 +/- 0.04 nM and 4.1 +/- 0.5 nM respectively, and displayed an average density of 0.55 +/- 0.05 pmol/mg and 0.4 +/- 0.03 pmol/mg protein respectively for the most enriched membrane fraction. The Ca2+ antagonist binding sites were solubilized from the membranes with the detergent 3-[(3-cholamidopropyl)dimethylammonio]propanesulfonate, and specific binding sites for [3H]PN200-110, [3H]verapamil and [3H]diltiazem were isolated on a wheat-germ lectin column. The binding sites for [3H]PN200-110 were enriched about 2,500 fold as compared with the original homogenate and displayed a density of 28.5 +/- 8 pmole/mg protein in the isolated fraction. Sodium dodecyl sulfate gel electrophoresis of the isolated drug binding proteins indicated enrichment of proteins of Mr 170,000, 140,000, 130,000, 100,000 and 53,000. The isolated receptor contained an intrinsic kinase activity that phosphorylated glycoproteins of Mr 170,000 and 53,000. Exogenously added cAMP-kinase stimulated phosphorylation of the 170,000, 100,000, 53,000 and 28,000 Mr glycoproteins in the receptor fraction. The results of this study indicate that the binding sites for [3H]nitrendipine, [3H]PN200-110, [3H]verapamil and [3H]diltiazem residue on glycoprotein(s) which are of sarcolemmal origin, and co-purify together on wheat germ lectin columns. The polypeptide composition of the Ca2+ antagonist binding sites from cardiac muscle appears to be very similar to that of the dihydropyridine receptor in skeletal muscle.