A new approach to the study of human B lymphocyte function using an indirect plaque assay and a direct B cell activator

Nicotine and periodontal tissues

Tobacco use has been recognized to be a significant risk factor for the development and progression of periodontal disease. Its use is associated with increased pocket depths, loss of periodontal attachment, alveolar bone and a higher rate of tooth loss. Nicotine, a major component and most pharmacologically active agent in tobacco is likely to be a significant contributing factor for the exacerbation of periodontal diseases. Available literature suggests that nicotine affects gingival blood flow, cytokine production, neutrophil and other immune cell function; connective tissue turnover, which can be the possible mechanisms responsible for overall effects of tobacco on periodontal tissues. Inclusion of tobacco cessation as a part of periodontal therapy encourages dental professionals to become more active in tobacco cessation counseling. This will have far reaching positive effects on our patients' oral and general health.

Periodontitis modified by systemic factors

Microbial dental plaque is the initiator of periodontal disease but whether it affects a particular subject, what form the disease takes, and how it progresses, are all dependent on the host defenses to this challenge. Systemic factors modify all forms periodontitis principally through their effects on the normal immune and inflammatory defenses. Some good examples of this effect exist such as when there is a reduction in number or function of polymorphonuclear leukocytes (PMNs) that may result in an increased rate and severity of periodontal destruction. Many other systemic factors are much less clear cut and are difficult to causally link to periodontitis. In many cases the literature is insufficient to make definite statements on links between systemic factors and periodontitis. It is also at times difficult to be precise regarding the causative agent in systemic exposures such as smoking and even prescribed drug therapy. The possible role of systemic diseases and systemic exposures in initiating or modifying the progress of periodontal disease is clearly a complex issue. It is however generally agreed that several conditions may give rise to an increased prevalence, incidence, or severity of gingivitis and periodontitis. The categorization of the systemic modifying factors causing periodontitis and the evidence to support the role of these factors are the focus of this review. An attempt has been made to consider the conditions under broad headings, but it will be clear that many conditions fall within more than one category and that for several conditions only case reports exist whereas in other areas an extensive literature is present.

IL-6 receptor (CD126'IL-6R') expression is increased on monocytes and B lymphocytes in HIV infection

Interleukin-6 (IL-6) is a multifunctional cytokine, with a wide range of effects on various cell types, including several types of cells involved in immune responses. IL-6 is believed to be involved in the pathogenesis of several diseases and may contribute to AIDS pathogenesis in various ways. Elevated levels of IL-6 occur in HIV infection. The objective of this study was to define the distribution of the expression of the 80-kDa alpha subunit of the IL-6 receptor (CD126'IL-6R') on immune cell subpopulations in HIV-infected subjects. CD126 is responsible for IL-6 binding, and its expression determines which cells respond to this cytokine. An elevated number of monocytes, B cells, and CD4 T cells expressing CD126 were seen in the peripheral circulation of HIV-infected subjects when compared to HIV-seronegative control subjects. Also, an increase in the density of CD126 expression was noted on monocytes. Generally, the observed increases in CD126 did not correlate with CD4 levels in HIV-infected subjects or with disease status, with the exception of CD126 expression on CD8 T cells, which was lower in those HIV-infected subjects that had AIDS. In some cases, increased CD126 expressing cells showed higher levels of STAT3 phosphorylation on exposure to recombinant IL-6. These results indicate that greatly elevated levels of CD126-expressing cells, particularly B cells and monocytes, are seen in HIV infection and suggest that the altered expression of CD126 may contribute directly or indirectly to immune dysfunction and to AIDS pathogenesis in HIV infection.

Immortalization by gene transfection

Cultured cell lines that maintain specific differentiated phenotypes have been indispensable tools in cell biology. Progress in understanding the function of differentiated cells in vivo can be facilitated by creating cell lines via immortalizing gene transduction, if they retain the essential differentiated features of the same cells in vivo. Rodent cells immortalize spontaneously with a frequency of 10(-5) to 10(-6). Thus, it is easy to isolate immortal cells from rodent cell populations even without the transfer of immortalizing genes. Immortalizing genes can be used to increase this frequency to approximately 100%. In contrast, the spontaneous immortalization of human cells is a very rare event; the frequency is thought to be < 10(-12). Immortalizing genes can also be used to increase this frequency. Several genes that promise efficient immortalization of cultured cells have been identified. Immortalizing genes include simian virus 40 large T antigen, papillomaviruses E6 and E7, adenovirus E1A, Epstein-Barr virus, human T-cell leukemia virus, herpesvirus saimiri, oncogenes, and mutant p53 gene. Equally important, innovative means of gene delivery have been developed as well. These immortalizing genes, together with gene transfer methodologies, have provided the means to generate cell lines from cell types that are not abundant or are difficult to obtain in pure form in primary culture, are in short supply as human cells, and/or have brief lifetimes in culture. This chapter focuses primarily on the immortalization method by gene transfection. The chapter is not meant to be comprehensive, but rather to provide an account of the power and usefulness of immortalization methodology.

Mitogenic activation of human lymphocytes: a protein A plaque assay evaluation of polyclonal B-cell activators

Using the protein A plaque assay, the capacity of various polyclonal B cell activators to induce differentiation in human B lymphocytes was investigated. Dextran sulphate and native dextran were both virtually devoid of mitogenic properties. Lipopolysaccharide, however, was found to be a potent mitogen in human cells that, although giving rise to low DNA synthetic response, induced high numbers of immunoglobulin-synthesizing cells. Mean plaque-forming cell (PFC) numbers in healthy blood donors assayed on the optimal day (days 5-7) were 23,493 IgM/10(6) cells, 11,288 IgG/10(6) cells, and 2643 IgA/10(6) cells. Values obtained in spleen cells, peaking at days 4-6, were slightly higher. Purified protein derivative (PPD) was equally or even more effective than lipopolysaccharide (LPS) in generating PFC of different subclasses in peripheral blood with mean of 29,241 IgM/10(6), 21,269 IgG/10(6), and 3681 IgA/10(6). PPD furthermore induced a marked DNA synthetic response in human lymphocytes. These data suggest that LPS and PPD may both be used as functional markers in human cells when analysing patients with a suspected immunodeficiency state. It is suggested that cultures should be assayed using the protein A plaque assay, thereby being able not only to investigate the individual immunoglobulin classes but also to avoid the possible hazards involved in measuring antigen-specific responses in patients whose prior immunization to the antigen tested can never be totally excluded.

Antigen-independent reactivation of anti-E, years after allogeneic bone marrow transplantation: a case report

Nine years after allogenic bone marrow transplantation a strong anti-E was observed in a patient transplanted with bone marrow from his HLA-identical brother. This IgG anti-E, with a titre of 4000, was detected together with autoantibodies to red blood cells and platelets and was not induced by transfusion with E+ cells. The hypothesis is proposed that the anti-E represents either antigen-independent desuppression of the donor immune system sensitized at the time of bone marrow transplantation by E antigens in the recipient, or antigen-independent memory B-cell activation by Epstein-Barr virus infection.

Decreased cytoplasmic immunoglobulin A production during Epstein-Barr virus immortalization on lymphocytes from patients with ataxia-telangiectasia

Previously, we have reported significantly lower immunoglobulin (Ig) A production in supernatants of cultured lymphoblastoid cells using enzyme-linked immunosorbent assay from patients with ataxia-telangiectasia (AT) when compared to that of age- and sex-matched healthy individuals. Here, we further assess the degree of cytoplasmic Ig production in these cells and also analyze it during the early phase of Epstein-Barr virus immortalization. All classes of cytoplasmic IgM, IgG, and IgA productions were demonstrated in cells from healthy controls. In contrast, cells from patients with AT showed only cytoplasmic IgM and IgG with low or nondetectable levels of IgA during and after the immortalizing process. These results suggest B lymphocytes bearing IgA are functionally immature and/or defective in patients with AT.

T-cell-independent stimulation of immunoglobulin secretion in resting human B lymphocytes by the mannose-specific adhesin of Escherichia coli type 1 fimbriae

Purified Escherichia coli type 1 fimbriae have been shown previously to stimulate T-cell-independent proliferation of human B lymphocytes. The response is mediated by the mannose-specific, lectin-like adhesin protein FimH. Here we show that type 1 fimbriae also stimulate immunoglobulin (Ig) secretion by B cells. The response was maximal at three days of culture and consisted predominantly of the IgM isotype. It was independent of serum components, T lymphocytes, monocytes, and natural killer cells. Highly purified resting B cells were induced to proliferate and secrete Ig in response to the fimbriae. The role of FimH in the response was shown by the failure of FimH- type 1 fimbriae to stimulate and by inhibition of the response with alpha-methyl mannoside. In light of the fact that carbohydrate-binding adhesins have been found on a wide variety of microorganisms, these studies suggest the possibility that responses of other cell types to other microbial adhesins will be discovered.

B-cell lymphoproliferative disorders after bone marrow transplant. An analysis of ten cases with emphasis on Epstein-Barr virus detection by in situ hybridization

Ten patients with B-cell lymphoproliferative disorders (BLPD) after bone marrow transplant were studied in a retrospective analysis of 81 specimens available from biopsy and autopsy material. Histologic review, immunophenotyping, and in situ hybridization (ISH) for Epstein-Barr virus (EBV) sequences were done. Sixty-four specimens showed morphologic evidence of BLPD, demonstrating a heterogeneous spectrum with various degrees of plasmacytoid differentiation. Immunophenotypic evidence of clonality was found in six patients. The ISH detected EBV sequences in all ten patients, including 60 of the 64 specimens with morphologic evidence of BLPD. In addition, ISH identified EBV-infected lymphoid cells in two of 17 sites without morphologic evidence of BLPD. These data demonstrate the utility of ISH for detecting EBV genome in this setting and provide further evidence for the etiologic role of EBV in the pathogenesis of BLPD.

Strong donor mononuclear cell reactivity for herpes simplex virus (HSV) antigen in HSV immune donors combined with recipient seropositivity for HSV is associated with acute graft-versus-host disease

Prior to bone marrow transplantation (BMT) titres of IgG antibodies for cytomegalovirus (CMV), herpes simplex virus (HSV) and varicella zoster virus (VZV) were analysed in 51 donors and recipients of allogeneic bone marrow. Donor mononuclear cells from peripheral blood and bone marrow cells were stimulated with antigen prepared from CMV, HSV and VZV. High IgG titres for HSV in the recipient were associated with grade II-III acute graft-versus-host disease (GVHD) (P = 0.05). Furthermore, the combination of positive IgG titre for HSV antibodies in the recipient, and strong donor blood mononuclear cell reactivity to HSV antigen in HSV immune donors, significantly increased the incidence of grade II-III acute GVHD (P = 0.04). The data suggest that HSV immune donor mononuclear cells may initiate a GVH reaction.

Immortalizing genes of Epstein-Barr virus

EBV immortalizes human B lymphocytes efficiently. Ten of its approximately 100 genes are expressed in these proliferating lymphoblasts and are candidates for mediating the changes central to the immortalization of the cell. Enough has been learned now about three of these viral genes to indicate that they are likely to be required for immortalization. As more is learned, additional genes of EBV will probably be found to support the process of immortalization of the host cell. EBNA-2 has been shown genetically to be required for EBV to immortalize an infected B lymphocyte. The biochemical activities of EBNA-2 that constitute this requirement have not been identified. Many experiments indicate that EBNA-2 affects the accumulation of specific viral and cellular RNAs. These effects, however, can be detected only in certain EBV-negative B-lymphoblastoid cells. It is, therefore, not clear that the known effects of EBNA-2 adequately explain its ubiquitous requirement in the immortalization of primary human B lymphocytes. LMP is likely to be required for immortalization because it can affect the growth properties of established human lymphoid and epithelial cells and can transform at least two established rodent cells to proliferate in an anchorage-independent manner. The structure of this viral protein, its position in the plasma membrane, many of its biochemical properties, as well as studies of its mutant derivatives are consistent with its acting as a growth factor receptor or affecting the activity of such a receptor. However, no biochemical activity has been assigned directly to LMP, and both its mechanism of action and its possible contribution to immortalization by EBV remain enigmatic. EBNA-1 presumably is required for EBV to immortalize a B lymphocyte because it is essential for the initiation of plasmid DNA replication by EBV. Circumstantial observations indicate also that EBNA-1 is probably necessary for sustaining viral DNA replication in the proliferating cell population. EBNA-1 may well affect the regulation of transcription of viral genes that themselves are required for immortalization. These roles of EBNA-1 are performed in part by its site-specific binding to the elements of oriP required in cis for the replication of EBV plasmid DNAs. It is probable that EBNA-1 also binds both to a set of cellular proteins that function in transcription and to a nonidentical set of cellular proteins that function in replication. EBV effects a fascinating phenotypic change in B lymphocytes it infects. It does so by using several viral genes that alter the physiology of the cell by different means.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro production of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) by Epstein-Barr virus-transformed B-cell lines in Wegener's granulomatosis

The frequent detection of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) in patients with Wegener's granulomatosis (WG) led to the supposition that this disease might be of autoimmune nature. For some authors assume that Epstein-Barr virus (EBV) infection of human B-lymphocytes besides polyclonal activation could reveal the cryptic immune status against different autoantigens in patients with autoimmune diseases we investigated EBV-transformed B-lymphocytes from patients with Sjögren's syndrome, mixed connective tissue disease, WG and healthy blood donors. Two stable B-cell lines (Ho3, We1) could be established. Inhibition experiments showed that antibodies produced by transformed B-lymphocytes and serum ANCA (C-ANCA type) of 10 WG patients recognized the identical antigen. Stimulation of one clone (Ho3) with interleukin 6 (IL-6) led to a switch from IgM to IgG production. Antibodies produced by this clone also stained glomeruli of human frozen kidney sections. Western blot analysis using immunoaffinity purified antigen prepared from human granulocytes revealed a reaction with a protein of approx. 29 kD MW. Our data underscore some new aspects concerning the direct pathogenicity of C-ANCA confirming the hypothesis that the autoimmune B-cell repertoire in WG not only reflects a polyclonal B-cell activation but is shaped by antigen driven responses.

In vitro studies on lymphocyte Fc gamma receptor blocking factors in human renal transplantation

In this study we have confirmed our earlier observation that the presence in pre-transplant serum of a high-molecular-weight lymphocyte Fc gamma receptor blocking factor correlates with improved human renal allograft survival. This factor was found to bind preferentially to B cells and to impair B cell function in vitro.

Analysis of immunoglobulin isotype blood levels, splenic B-cell phenotypes, and spleen cell immunoglobulin gene expression in mice infected with lactate dehydrogenase-elevating virus

B-lymphocyte activation was studied in mice infected with lactate dehydrogenase-elevating virus (LDV). ELISA determinations of blood total immunoglobulin levels demonstrated that, at 10 days post-infection (p.i.) with LDV, only the IgG2a isotype was elevated. DNA-excess dot-blot hybridization showed that RNA specific for IgG2a and IgA immunoglobulin isotypes was increased in the spleens of mice at 10 days p.i. with LDV. Immunoglobulin surface phenotype analysis of spleen cells at 8-10 days p.i. with LDV revealed that there was no alteration in immunoglobulin isotype-bearing cell proportions, although total spleen mass and number of cells increased during LDV infection. When blood immunoglobulins from LDV-infected mice were analyzed by two-dimensional isoelectric focusing gels, followed by specific immunoblotting for immunoglobulin isotype, the presence of new IgG2a species was observed at 10 days p.i.

Normal suppressive T cell function of Epstein-Barr virus induced B cell activation in type 1 (insulin dependent) diabetes mellitus

Several studies have demonstrated abnormalities of T cell regulation of Epstein-Barr virus-induced B cell activation in systemic autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematous, and systemic sclerosis. However, a normal suppressive peripheral T cell function was observed in Graves' disease. To investigate whether this abnormality is a common feature to other autoimmune diseases, we studied T cell regulation of Epstein-Barr virus induced B cell activation in 15 newly diagnosed type 1 (insulin dependent) diabetes mellitus patients and 10 normal control subjects. Peripheral B lymphocytes infected with Epstein-Barr virus were cultured for 20 days in the presence or absence of autologous T cells at different ratios (1:1 and 1:4). IgM and IgG secretions into the supernatants were determined using an enzyme-linked immunosorbent assay. The extent of suppression when T cells were added, as measured by a suppression ratio, was not significantly different in type 1 (insulin dependent) diabetes mellitus patients and normal subjects. We conclude that in type 1 (insulin dependent) diabetes mellitus, the autoimmune reactivity is not dependent upon a generalized suppression defect. It can be hypothesized, therefore, that in type 1 diabetes mellitus as well as in Graves' disease, a local or organ specific suppressor deficit may induce the autoimmune phenomena.

Unusual manifestations of Epstein-Barr virus encephalomyelitis

A patient with atypical manifestations of Epstein-Barr Virus (EBV) encephalomyelitis is presented. The patient had unusual spinal fluid immunoglobulin abnormalities, the syndrome of inappropriate anti-diuretic hormone secretion, autonomic dysfunction and spinal arachnoiditis. The cisternal CSF, with a very high IgG level (34.3 mg/dl; normal less than 6.1) but a normal albumin content, displayed evidence of massive intrathecal immunoglobulin production. This was further confirmed by the presence of oligoclonal bands. These clinical manifestations have not previously been reported in encephalomyelitis associated with EBV infection.

Stimulation of human B lymphocyte differentiation by the neuropeptides substance P and neurokinin A

Substance P (SP) at a concentration of 10(-7) M significantly increased the number of IgG-producing cells induced by the polyclonal activator Staphylococcus aureus protein A (SpA) in 11 out of 22 cultures of enriched human blood B lymphocytes, in nine cultures SP did not significantly affect the SpA response and in three cultures IgG secretion was decreased in the presence of SP. Stimulation by SP was observed in cultures at days 6 and/or 8. In 3 out of 4 cell cultures depleted of monocytes SP did not affect the cell response to SpA stimulation. SP antagonists inhibited the enhancing effect of SP on B-cell antibody secretion induced by SpA. SP alone did not stimulate B lymphocytes. Neurokinin A (NKA) had similar effects as SP and enhanced the IgG secretion induced by SpA in 5 out of 9 experiments, in two experiments was inactive, and in one decreased the IgG secretion. The effect of SP and NKA on B lymphocytes suggest that the neuropeptides interact with the regulation of the immune response.

Gamma-interferon-induced monocyte major histocompatibility complex class II antigen expression individuals with acquired immune deficiency syndrome

Twelve patients with the acquired immune deficiency syndrome (AIDS) and Kaposi's sarcoma were treated with recombinant human gamma-interferon (rIFN-gamma). A rapid, substantial increase in the fraction of HLA-DQ-positive monocytes was noted after treatment with rIFN-gamma. The rIFN-gamma-induced increase in monocyte HLA-DQ was seen throughout the course of treatment, with the percentage of HLA-DQ-positive monocytes dropping slightly following each week's treatment with rIFN-gamma and then rapidly increasing following the next course of treatment. Although the percentage of HLA-DR-positive monocytes was unchanged (HLA-DR was expressed on greater than 80% of monocytes prior to treatment), the density of HLA-DR on monocytes also increased following rIFN-gamma treatment. Following rIFN-gamma treatment, no changes were seen in CD3, CD4, CD8 T cell numbers, in T cell subset ratio (CD4/CD8), in Leu 7 or CD16 (Leu 11) cell number, in spontaneous Ig secretion, in PHA-induced in vitro proliferation, or in NK activity. These results indicate that exposure to rIFN-gamma in vivo led to the increased expression of class II antigens on monocytes in patients with AIDS.

Human B cell lines secreting IgM antibody specific for myelin basic protein

In this study we describe for the first time the production of stable human B cell lines and clones that secrete IgM antibody specific for human myelin basic protein. The technique based on limiting dilutions of Epstein-Barr virus-transformed peripheral B cells from patients with multiple sclerosis, precluded the need for preselecting or stimulating antigen-specific B cells. Most of the cell lines were stable for at least 6 months in continuous culture and produced 5-12 micrograms/ml antibody after 2 weeks in culture. The myelin basic protein-specific B cells were surface IgM positive, and occurred with a frequency of approximately 1/2500 mononuclear cells in peripheral blood. The successful selection and quantitation of specific B cell clones described here suggests that this technique is well suited for evaluating B cell responses to known and suspected antigens and autoantigens.

Human B cell lines secreting IgM antibody specific for myelin basic protein

In this study we describe for the first time the production of stable human B cell lines and clones that secrete IgM antibody specific for human myelin basic protein. The technique based on limiting dilutions of Epstein-Barr virus (EBV)-transformed peripheral B cells from patients with multiple sclerosis precluded the need for preselecting or stimulating antigen-specific B cells. Most of the cell lines were stable for at least 6 months in continuous culture and produced 5-12 micrograms/ml antibody after 2 weeks in culture. The myelin basic protein (MBP)-specific B cells were surface IgM positive, and occurred with a frequency of approximately 1/2500 mononuclear cells in peripheral blood. The successful selection and quantitation of specific B cell clones described here suggests that this technique is well suited for evaluating B cell responses to known and suspected antigens and autoantigens.

Stability of specific immunoglobulin secretion by EBV-transformed lymphoblastoid cells and human-murine heterohybridomas

We have examined variables leading to the generation of stable, antigen-specific, human immunoglobulin-secreting cell lines. Peripheral blood B lymphocytes enriched for Thomsen-Friedenreich antigen (T antigen)-specific cells were transformed with Epstein-Barr virus. Lymphoblastoid cells (LC) reactive with T antigen were either expanded without cloning or cloned at limiting dilution and then fused with murine 653 cells. Uncloned LCs from three transformations secreting polyclonal anti-T antibody (7-18 micrograms/ml/10(6) cells/24 hr total immunoglobulin) were subcultured at 100 cells/well, and T antigen-reactive cultures pooled. These cultures quickly lost specific antibody secretion, presumably due to overgrowth by clones of unknown specificity. T antigen-reactive LCs that were cloned three times at limiting dilution secreted 0.2 - 6.1 micrograms/ml/10(6) cells/24 hr but died or stopped secreting specific immunoglobulin after 77 to 155 days in culture. Pooling T antigen-reactive clones after each cloning step did not increase the long term stability compared to unpooled clones (p = 0.2). Fusions between cloned LCs and 653 cells failed to yield viable hybrids in nine of ten attempts with seven different LC lines. In contrast, fusion of uncloned LCs and 653 cells resulted in the generation of viable immunoglobulin-secreting heterohybrids in 22 of 24 fusions. The heterohybridomas produced from fusion of uncloned T antigen-reactive cultures with 653 cells secreted significantly more antibody (frequency of cell lines secreting greater than 2 micrograms/ml/10(6) cells/24 hr, p less than 0.01) and higher titers of antibody (frequency of cell lines secreting greater than four hemagglutination units of T antigen-specific antibody, p less than 0.03) than cloned lymphoblastoid cells. The hybrids maintained specific immunoglobulin secretion for longer in culture than either cloned or uncloned lymphoblastoid cell lines (p less than 0.001).

Selective decrease in Leu8-negative T cell subpopulations following treatment with recombinant interferon-alpha 2a (rIFN-alpha 2a)

The effects of in vivo treatment with recombinant human IFN-alpha 2a (rIFN-alpha 2a) on the distribution of T cell subpopulations were examined in 21 patients with renal cell adenocarcinoma, using two-color flow cytometry with anti-Leu8 in combination with anti-Leu2 and anti-Leu3. Other parameters indicative of immune status, such as the number and percentage of total (CD3) T cells, in vitro proliferation to mitogen, and spontaneous immunoglobulin secretion, were also measured, prior to the initiation of treatment with rIFN-alpha 2a, and during treatment. Total T cell number decreased after treatment with rIFN-alpha 2a, to a low of 54% of mean pretreatment values after 4 weeks. The CD4/CD8 ratio did not change appreciably following treatment with rIFN-alpha 2a. However, the number of Leu8-negative T cells, within both the CD4 and the CD8 T cell populations, decreased more than the number of Leu8-positive T cells. An increase in spontaneous immunoglobulin-secreting cells followed treatment with rIFN-alpha 2a.

DNA analysis of stimulated lymphocytes by automatic sampling for flow cytometry

A microsample delivery system (MSDS) was tested for automatic flow cytometry (FCM) analysis of DNA synthesis in stimulated human peripheral blood lymphocytes (PBL) cultivated in wells of microtiter plates. After incubation, either for 1-3 days with phytohemagglutinin, concanavalin A, and pokeweed mitogen, or for 7 days with allogenic PBL, the cells, while in the wells, were washed in hypotonic Tris buffer and stained with ethidium bromide-RNAse solution. The results obtained from quintuplicate replicated wells, each of the five containing the same control or stimulated cultures, were reproducible in terms of the number of nuclei counted in each histogram of control, mitogen-stimulated PBL, and mixed lymphocyte cultures (MLC). Using a computer program that superimposes histograms and calculates their differences on the scale of fluorescence intensity, it was possible to quantify the intensity of the response to the mitogenic stimuli. This approach to the study of lymphocyte proliferation offers not only a simpler and faster analysis of DNA synthesis than the method of 3H-thymidine incorporation, but it also allows for the analysis of other FCM parameters, such as forward and 90 degrees light scatter and double fluorescence labelling of PBL nuclei.

T-cell-mediated suppression of Epstein-Barr virus-induced B lymphocyte activation in multiple sclerosis

Significantly reduced levels of T-cell-mediated "suppression" of numbers of Epstein-Barr virus (EBV)-activated B lymphocytes which secrete IgG or IgM were found in preparations of mononuclear cells (MNC) from peripheral blood of 28 patients with multiple sclerosis (MS) compared with 28 healthy subjects, all seropositive for EBV. A statistically significant correlation was not found between the suppression of EBV-induced activation of B lymphocytes and either EBV-specific T-cell-mediated cytotoxicity or numbers of T8-positive cells.

Drugs and the periodontium

The periodontium and periodontal disease activity can be affected by systemic drug therapy. Many drugs can have an adverse effect on the periodontium, i.e., gingival hyperplasia. Alternatively, some drugs can modify the inflammatory and immunological responses of the periodontal tissues to bacterial plaque. The aim of this review is to evaluate the effects of drug therapy on the periodontium and periodontal disease activity, and where possible, to relate such changes to the pharmacodynamics of the drugs considered. Drugs which have been reported to affect the periodontium can be categorised as follows: anti-epileptics, immunosuppressants, corticosteroids, non-steroidal anti-inflammatory drugs and hormones. Those drugs whose pharmacodynamics are clearly established and which affect the rate of periodontal disease activity, may provide information on the mechanisms of periodontal destruction. Finally, the mechanisms of drug-induced gingival hyperplasia (overgrowth) are discussed in relationship to the drugs' pharmacodynamics and pharmacokinetics.

Polyclonal antibody secretion during acute graft-versus-host disease

Spontaneous plaque-forming cells (S-PFC) were followed in 67 bone marrow transplantation (BMT) recipients and 41 controls. Patients with no acute graft-versus-host disease (GVHD) had decreased IgA and IgM S-PFC up to 7 weeks after BMT compared with controls. Patients with acute GVHD had increased IgG, IgA, and IgM PFC compared with controls and patients without GVHD during the first 4 weeks after BMT. The maximum number of S-PFC increased with increasing severity of acute GVHD. However, at diagnosis of GVHD there was no difference in S-PFC in patients who resolved their GVHD or in those who developed more severe GVHD. After 6 weeks, patients with acute GVHD had significantly decreased IgA and IgM S-PFC compared with normal. No major changes in S-PFC were induced during various infections. However, a patient who developed urticaria had a dramatic increase in S-PFC. Patients studied more than a year after BMT had reduced IgM S-PFC compared with controls. It is concluded that S-PFC are reduced after BMT, but markedly enhanced during acute GVHD.

In vitro and in vivo stimulation of murine lymphocytes by human respiratory syncytial virus strains

Respiratory syncytial virus (RSV) strains of subtype A (A2, WV9894, and WV12138) and of subtype B (WV1293, WV4843, and WV6873) are mitogenic in vitro for unprimed BALB/c spleen cells. The virus also triggered splenocytes in vitro to secrete immunoglobulins. Plaque-purified and UV-irradiated materials of both RSV subtypes produced comparable levels of DNA synthesis. Infectious materials of both subtypes also induced pronounced responses. Lymphocyte activation with UV-inactivated RSV strain A2 was dose-dependent and maximal responses occurred after 4-5 days of incubation. The virus preparations were mitogenic for spleen cells depleted of T lymphocytes by treatment with anti-Thy 1.2 and complement and for lymphocytes of congenitally athymic mice (nu-nu). They were also mitogenic for highly purified T lymphocytes separated by panning of spleen cells on anti-mouse Ig-coated Petri dishes, suggesting that both B and T lymphocytes respond to the mitogenic activity of RSV. Moreover, mice infected intranasally with RSV strain A2 generated local as well as peripheral cellular and humoral responses.

Analysis and comparison of immune reactivity in guinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariae of Schistosoma mansoni

Guinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariae of Schistosoma mansoni are known to develop close to complete resistance to reinfection at weeks 12 and 4.5 respectively. We here analyse and compare the immune responses induced by the two populations of cercariae. Both radiation-attenuated and normal parasites of S. mansoni elicited an extensive germinal centre response in guinea-pigs by week 4.5 post-immunization. The anti-parasite antibody titre and cytotoxic activity of serum from 4.5-week-vaccinated, or 4.5-week-infected guinea-pigs were approximately equal, but sera from 12-week-infected individuals had high titres of anti-parasite antibody, which promoted significant larvicidal activity in vitro. In all cases, larvicidal activity was mediated by the IgG2 fraction of the immune serum. Lymphocyte transformation tests conducted on splenic lymphocytes from 4.5-week vaccinated guinea-pigs revealed maximal stimulation against cercarial, 2-week and 3-week worm antigens, whereas spleen cells from 4.5-week-infected guinea-pigs were maximally stimulated by cercarial and 6-week worm antigens. The splenic lymphocyte responses of 12-week infected animals were dramatic against antigens prepared from all life-stages of the parasite.

Epstein-Barr virus-transformed human precursor B cell lines: altered growth phenotype of lines with germ-line or rearranged but nonexpressed heavy chain genes

A series of lymphoblastoid cell lines (LCLs) have been established by in vitro infection of fetal bone marrow and fetal liver cells with Epstein-Barr virus (EBV). While most lines showed the usual mature B cell phenotype, a small proportion were cytoplasmic and surface immunoglobulin (Ig) heavy and light chain negative. Analysis of gene rearrangements indicated that the Ig- lines were either germ-line or nonproductively rearranged when probed for JH and were in germ-line configuration for C chi; no mu or chi mRNA could be detected in such cells. Precursor B cell lines were indistinguishable from their normal Ig+ counterparts in their expression of a wide variety of cell surface markers including "activation" antigens usually associated with the lymphoblastoid state; even the single LCL showing germ-line heavy and light chain genes expressed B lineage-specific cell surface antigens. However, the Ig- lines were distinct from their Ig+ counterparts in three important respects: (a) they grew much more slowly and achieved lower saturation densities, (b) they showed unusually high proportions (8-16%) of cells in EBV-productive cycle, and (c) they contained unusually high proportions (up to 40%) of cells expressing free joining (J) chain. These results suggest that precursor B cells differ in their response to the growth-transforming effects of EBV such that the virus-cell interaction in precursor B cell lines is inherently less stable than in conventional LCL. In particular there may be a greater movement of cells out of cycle and along the B cell maturation pathway. It is possible that such movement leads in individual cells either to virus replication or to a "sterile" plasmacytoid differentiation with J chain expression in the absence of Ig synthesis.

Increased spontaneous immunoglobulin secretion associated with cyclophosphamide-induced immune suppression

Spontaneous immunoglobulin (Ig) secretion by cells from multiple sclerosis (MS) patients (in the progressive phase) treated with monthly pulse doses of cyclophosphamide (CY) (1000-1600 mg/M2) was measured using the protein A plaque assay, to evaluate the effect of CY treatment on B-cell function. Surprisingly, an increase, rather than a decrease, in Ig-secreting cells was seen following CY treatment. CY-treated MS patients averaged 1380 +/- 535 spontaneous total (IgM + G + A) Ig plaque-forming cells (PFC) per 1 X 10(6) peripheral blood mononuclear cells (MNC), measured at 15-22 days after monthly CY administration, while healthy adults had 280 +/- 47 Ig PFC/10(6) MNC, and MS patients not treated with CY had 300 +/- 43 Ig PFC/10(6) MNC. The observed increase was due to an increase in IgG and IgA PFC. PFC levels remained elevated for 4 weeks following CY treatment, decreasing to control levels by 7-8 weeks post-CY. A small increase in serum IgG level was noted after greater than 12 months of pulse CY therapy; no increase was seen in CSF IgG levels. A preferential decrease in the number of CD4+ T cells was also seen in the CY-treated MS patients. We propose that the observed increase in the number of spontaneous Ig PFC was due to the CY-induced disruption of the CD4+ T cell-mediated control of in vivo activated B cells.

Synergistic activation of cells by Epstein-Barr virus and B-cell growth factor

Infection with Epstein-Barr virus (EBV) is initiated by virus binding to the C3dg-C3d receptor CR2. Several workers have implicated this receptor in the control of B-cell activation by examining the effects of antibodies to CR2 and isolated C3d on B-cell proliferation and differentiation. We report here on the activating effects of irradiated EBV, which retains its capacity to bind to CR2 but loses its ability to function as a T-independent B-cell activator. EBV synergized with B-cell growth factor in the induction of uptake of tritiated thymidine by T cell-depleted leukocytes from seronegative donors but did not induce secretion of immunoglobulin. Synergism could be inhibited with an anti-viral antibody that inhibited binding of EBV to CR2. No similar synergism was found between EBV and recombinant interleukin 2, interleukin 1 alpha, or gamma interferon or with the lipid A fraction of bacterial lipopolysaccharide. EBV may thus initiate B-cell activation as it binds to CR2. Infectious virus may, under normal circumstances, induce the cell to make those growth factors necessary to support B-cell proliferation; the difficulty of transforming cells with transfected EBV DNA may in part reflect the absence of an activation event provided by intact virus as it attaches to CR2. The synergism of EBV and B-cell growth factor more clearly distinguishes the effects of B-cell growth factor from those of interleukin 1 and interleukin 2 in other models of B-cell activation. Thus, this may be a useful model for further delineation of unique effects of B-cell growth factor on B-cell function.

Jacalin, an IgA-binding lectin, inhibits differentiation of human B cells by both a direct effect and by activating T-suppressor cells

Jacalin, a lectin extracted from the seeds of Artocarpus intergifolia (jackfruit), has been reported to bind specifically to IgA while inducing B-cell polyclonal immunoglobulin secretion. We confirmed that jacalin only binds to IgA and not to IgG or IgM and extended these findings by showing that it does not bind to IgE. Addition of jacalin to either unfractioned peripheral blood lymphocytes or purified B cells failed to induce immunoglobulin synthesis; indeed immunoglobulin production was diminished in the presence of jacalin. We found that jacalin directly inhibited the induction of immunoglobulin synthesis from B cells in the presence of T-cell replacing factor. Cell lines making IgG, IgM, and IgA were inhibited by jacalin. Furthermore, T cells incubated with jacalin also inhibited immunoglobulin production by stimulated B cells. Under these conditions jacalin was found to be a potent mitogen for T cells but to induce little or no activation of B cells. Jacalin appears to be a potent T-cell mitogen which can induce suppressor T cells for Ig production. It also has a direct inhibitory effect on B-cell Ig production.

Detection by monoclonal antibodies of an early membrane protein induced by Epstein-Barr virus

Two monoclonal antibodies, E8B3 and E8D2, were raised against Epstein-Barr virus (EBV)-producing cells and were shown to immunoprecipitate a protein with an approximate molecular weight of 105,000 (p105). The protein was detectable only in EBV-containing cells which were supporting the virus lytic cycle, and its synthesis increased after cells were induced with phorbol esters. The molecule was radiolabeled and immunoprecipitated from virus-producing cells that had been extrinsically labeled with 125I, and the antibodies E8B3 and E8D2 reacted in immunofluorescence assays with infected cells; the molecule was also associated with virion particles. Synthesis of p105 was not blocked by phosphonoacetic acid and could be induced in Raji cells by superinfection with virus derived from P3HR1 cells. These data support the conclusion that p105 is an EBV-specific early membrane protein.

Polymyositis and molecular mimicry, a mechanism of autoimmunity

The amino acid sequences of Escherichia coli histidyl-tRNA synthetase and alanyl-tRNA synthetase, two proteins recently identified as autoantigens in polymyositis, were compared by a computer alignment procedure with those of the 3600 proteins tabulated in the National Biomedical Research Foundation protein sequence database. Both proteins contain sequences long enough to function as epitopes that match sequences on viral and muscle proteins. The homology thus revealed not only lends strong support to mechanisms of autoimmunity that invoke the theory of molecular mimicry of viral proteins, but also suggests a rationale for the skeletal muscle target of polymyositis.

Direct polyclonal activation of human B lymphocytes by the acquired immune deficiency syndrome virus

When B lymphocytes from normal human peripheral blood were incubated for 1 hour with the retrovirus that causes the acquired immune deficiency syndrome (AIDS), the B cells showed marked proliferation and differentiation. Proliferative responses to the virus peaked on day 4 and appeared to be independent of accessory cells. This finding was repeated with three separate viral isolates, one of which was from a patient from Zaire. The magnitude of the observed responses was comparable to that seen with standard polyclonal B-cell activators. This phenomenon may be at least partially responsible for the polyclonal B-cell activation seen in patients with AIDS.

Induction of immunoglobulin secretion and DNA synthesis in human lymphocytes in vitro by cytomegalovirus preparations

Immunoglobulin secretion as evidenced by plaque-forming cells (PFC) in an indirect haemolysis-in-gel assay, and DNA synthesis were induced in human blood lymphocytes by the following preparations of cytomegalovirus (CMV): Nucleocapside Nc-CMV antigen, membrane M-CMV antigen, crude C-CMV preparations and CMV-incubated adherent cells. Peak stimulations occurred around day 6 in culture. Nc-CMV and M-CMV only stimulated PFC and DNA synthesis in lymphocytes from CMV seropositive individuals. C-CMV also stimulated lymphocytes from CMV seronegative individuals but gave better responses in lymphocytes from CMV seropositive individuals. CMV-incubated adherent cells occasionally stimulated lymphocytes from CMV seronegative individuals but always in CMV seropositive blood donors. Nc-, M-, and C-CMV gave high numbers of PFC in B cells enriched by sheep erythrocyte sedimentation and in co-cultures of enriched T and B cells. Almost no PFC were induced in enriched T cells. DNA synthesis induced by all the three antigenic CMV preparations increased after removal of adherent cells. Strong DNA synthesis was induced in enriched T cells compared to almost none in enriched B cells. It is concluded that some pure CMV preparations act as antigens and more crude preparations induce polyclonal activation. Different CMV preparations may be used to diagnose CMV, to study immune reactivity against CMV and as a model for CMV infections in vitro.

Transient immune deficiency in patients with acute Epstein-Barr virus infection

To study the effect of primary Epstein-Barr virus (EBV) infection on antigen-specific antibody production, we immunized 17 college students who had developed acute infectious mononucleosis with the T-cell dependent neoantigen bacteriophage phi X174. During the early phase of infectious mononucleosis, the proportion of peripheral blood lymphocytes displaying Ia and T8 (CD8) phenotypes was increased and the T helper/suppressor (T4/T8) ratio was decreased (less than 1). These abnormalities disappeared during the convalescent phase. Correlating with EBV-induced changes in T lymphocytes, we demonstrated depressed humoral immune responses to bacteriophage phi X174 both in vivo and in vitro. In vitro coculture experiments indicated that the Ia+ suppressor T cells could inhibit antibody production and isotype switch. Removal of T8+ lymphocytes from patient T cells normalized in vitro antibody synthesis. In addition, impaired B-cell function was shown to be in part responsible for deficient antibody production. These studies demonstrate that infection with EBV affects both B and T lymphocytes and causes a broad-based transient immune deficiency in patients with uncomplicated infectious mononucleosis.

Defective Epstein-Barr virus specific suppressor T cell function in progressive systemic sclerosis

Several immunoregulatory defects of Epstein-Barr virus (EBV) induced B cell activation have been described in patients with rheumatoid arthritis (RA), suggesting that EBV may have a role in the pathogenesis of RA. We assessed EBV specific T cell regulation in 20 patients with progressive systemic sclerosis (PSS) and immune to EBV and in 10 control subjects also immune to EBV by comparing the secretion of IgM into supernatants of 16 day cultures of B cells alone and cocultures of B and autologous T cells. In control subjects autologous T cells mediated a significant decrease in the secretion of IgM by B cells at 12 and 16 days of culture. Analysis of individual responses showed the existence of two subgroups of patients with PSS: group I (10 patients) had a suppressor T cell function similar to that of controls; group II (10 patients) had a defective T cell function. Differences in the duration or severity of the disease, the slow acting therapeutic agents, and anti-inflammatory drugs could not account for these subdivisions. These results suggest that several immunoregulatory defects of EBV induced B cell activation exist in different connective tissue diseases.

The Epstein-Barr virus-induced production of IgE by human B cells

B cells, isolated from the blood of healthy individuals and patients allergic to pollen, produced IgE when exposed to the human B-cell polyclonal activator, Epstein-Barr virus (EBV) in vitro and placed in culture. Secreted IgM and IgE were measured using immunoenzymatic assays. No difference was seen between healthy donors and allergic patients in the amount of IgE (or IgM) secreted. Cells were placed in limiting dilution cultures in order to determine the frequency of cells producing IgE or IgM (total and pollen specific) on exposure to EBV. Again, no significant differences in EBV-driven, B-cell precursor frequencies (PF) were seen between normal and allergic individuals. EBV-driven B-cell PF for total IgM and IgE, and pollen-specific IgM and IgE secretion, were 1/450, 1/6500, 1/83,000, and less than 1 per 2,500,000, respectively, for cells from healthy donors, and 1/140, 1/4000, 1/56,000 and less than or equal to 1 per 2,000,000, respectively, for cells from allergic patients. We propose that the increased IgE levels seen in atopic individuals result solely from regulatory defects, rather than an increase in the frequency of B cells committed to the secretion of IgE.

Modification of Epstein-Barr virus replication by tunicamycin

The effect of tunicamycin, which inhibits N-linked glycosylation, on the replication of Epstein-Barr virus was examined. Tunicamycin markedly reduced the yield of virus from producing cells. At concentrations of 1 to 2 micrograms of tunicamycin per ml, there was a buildup of intracellular virus in P3HR1-Cl13 cells but not in MCUV5 cells; at a concentration of 5 micrograms of tunicamycin per ml in P3HR1-Cl13 cells, viral DNA synthesis was inhibited as well. Viral glycoproteins lacking N-linked sugars were apparently inserted into the cell membrane, and the small amount of virus made in the presence of drug was able to bind specifically to its receptor on B cells. However, the ability of the virus to induce immunoglobulin secretion by fresh human lymphocytes was impaired. This implies a role for viral glycoproteins in the penetration as well as the attachment of virus.

The role of receptors for complement in the induction of polyclonal B-cell proliferation and differentiation

A panel of monoclonal antibodies and ligands that bind to the CR1 or CR2 complement receptors of B cells has been used to investigate the role of these membrane molecules in regulating B-cell proliferation and differentiation. When CR2 was modulated from the surface of B cells by treatment with the HB-5 antibody and a secondary goat anti-mouse immunoglobulin antibody, Epstein-Barr virus-induced polyclonal B-cell proliferation and immunoglobulin production were inhibited by 83 and 90%, respectively. In contrast, modulation of other cell surface molecules, HB-2, B1, and the C3b receptor (CR1), or pretreatment of B cells with C3d,g (a CR2 ligand) or HB-5 antibody, alone minimally inhibited these responses. Neither the HB-5 antibody C3d,g, nor a monoclonal antibody (YZ-1) reactive with CR1 induced resting B cells to proliferate, nor did they alter anti-mu antibody-induced proliferation. Similarly, treatment with C3d,g or with the HB-5 or YZ-1 antibodies did not induce B cells to secrete immunoglobulin or affect pokeweed mitogen-induced plasma-cell formation. Whereas CR2 appears to be the functionally relevant receptor for Epstein-Barr virus on B cells, the effects of ligand interactions with CR1 and CR2 on normal B-cell proliferation or differentiation remain unidentified.