Diagnosis of nasopharyngeal carcinoma by DNA amplification of tissue obtained by fine-needle aspiration

BACKGROUND

In nasopharyngeal carcinoma the primary lesion is often difficult to find. Metastatic lesions occur frequently but are difficult to distinguish from other head and neck tumors. The viral genome of the Epstein-Barr virus (EBV) can be identified in the cells of this carcinoma.

METHODS

We used the polymerase chain reaction (PCR) to test for the presence of EBV genomes in 15 samples of metastatic squamous-cell carcinoma of the neck obtained by fine-needle aspiration and in 26 samples obtained by biopsy of lymph nodes. For controls we used disease-free lymph nodes from 10 patients with various head and neck tumors, tonsillar tissue from 46 subjects, blood from 59 EBV-seropositive blood donors, and mononuclear cells from 8 patients with fatal lymphoproliferative lesions.

RESULTS

Of the 41 malignant lesions examined, only the nine nasopharyngeal carcinomas (one primary lesion and eight metastases) contained EBV genomes. None of the 20 nodes with other types of cancer, the 10 disease-free nodes, or any of the 105 normal control samples contained detectable EBV. In two patients with suspected metastases from occult primary tumors, the presence of EBV was predictive of nasopharyngeal carcinoma; in both cases overt nasopharyngeal carcinoma developed within one year.

CONCLUSIONS

In patients with suspected nasopharyngeal carcinoma, fine-needle aspiration can provide tissue for diagnosis by DNA amplification of EBV genomes. The presence of EBV in metastases from an occult primary tumor is predictive of the development of overt nasopharyngeal carcinoma.

Milk proteins in the etiology of insulin-dependent diabetes mellitus (IDDM)

The etiology of insulin-dependent diabetes mellitus (IDDM) is multifactorial. The final cause of the disease, the specific destruction of the islet beta-cells, is the result of a cellular/humoral autoimmune process that operates in individuals with a particular genetic background in response to an external triggering factor(s). The most likely environmental triggers are virus infections and dietary factors. Among the latter group dietary proteins, mainly cow milk proteins, have been found to be important. Elimination of intact cow milk proteins from the diet significantly reduced the incidence of IDDM in the spontaneously diabetic BB rat, the elimination being most effective when it occurs during the pre-weaning period. Conversely, in newly discovered diabetics (both rats and children) increased levels of antibodies to cow milk proteins as compared with non-diabetic controls were found. These higher titres of antibodies were against beta-lactoglobulin and anti-bovine serum albumin. In further studies we found that antibodies to bovine serum albumin cross-react with a beta-cell membrane protein of Mr 69,000 and that this protein is likely induced by interferon. At the molecular level, a region of the bovine serum albumin has distinct homology to the beta-subunits of the MHC class II proteins Ia, DQ and DR, and antibodies raised against this bovine serum albumin region identified the same 69K beta cell membrane protein, in the same manner as antibodies to the third hypervariable region of DR-beta did. Our hypothesis is that bovine milk proteins (mainly bovine serum albumin) might be an important environmental factor providing specific peptides that share antigenic epitopes with host cell proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

A deletion map of the human immunoglobulin heavy chain variable region

Analysis of VH gene segments deleted in the process of immunoglobulin heavy chain (IGH) variable region assembly in three series of monoclonal B cell lines has been used to determine the human VH region organization. A deletion map of the relative positions of 21 different VH gene segments has been determined. The characterization of B cell lines from three unrelated adults of two racial groups yielded the same relative VH gene segment order, suggesting that the overall order of VH genes in the normal population is constant. This VH gene segment order was consistent with what we had previously generated from physical mapping techniques. DH segments from the second DH cluster, distinct from the major DH locus 3' of the VH region, were not observed to be used in 32 different rearrangements. Approximately 77% of the VH-(D)JH rearrangements involved VH gene segments within 500 kb of the JH region, indicating that human B cell lines preferentially rearrange JH-proximal VH gene segments. The switch, observed in mice, from the fetal use of JH-proximal VH gene segments to an adult VH use dependent upon VH family size may therefore not occur in humans. This detailed map of the VH gene segments is a necessary prerequisite for understanding VH usage in development and disease.

Exogenous but not endogenous EBV induces lymphomas in beige/nude/xid mice carrying human lymphoid xenografts

Epstein--Barr virus (EBV) is a latent human herpes virus that growth-transforms EBV receptor/CD21+ B cells and is associated with several high-frequency malignancies. Reactivation of latent EBV occurs in approximately 1/3 of organ graft recipients and a majority of AIDS patients; EBV-positive B lymphoproliferative lesions represent often fatal complications in organ transplantation and late-stage AIDS. Although such lymphomas can arise from endogenous virus, the high tumor risk in EBV-seronegative transplant recipients implies de novo infection, in particular virus transmission with intra-graft B lymphocytes. Since SCID mice engrafted with human lymphocytes (SCIDhum) typically develop endogenous EBV+ (human) tumors in their graft it is difficult to study exogenous virus transmission in this model. We here demonstrate that beige/nude/xid mice engrafted with human lymphoid cells (BNXhum) selectively accept human B but not T cell grafts. Unexpectedly these mice fail to develop endogenous lymphomas observed in SCIDhum mice engrafted in parallel. However, injection of as few as less than 500 EBV particles produces rapidly fatal, polyclonal lymphomas in BNXhum animals. This virus sensitivity of BNXhum approaches conditions for EBV transmission with organ grafts.

The tyrosine kinase lck is critically involved in the growth transformation of human B lymphocytes

Epstein-Barr virus (EBV) exposure of human B lymphocytes induces rapid, Ca(2+)-dependent tyrosine phosphorylation of two cytosolic proteins, one likely the CD21 EBV receptor and another unknown species of 55-60 kDa. We now identify the latter protein as the tyrosine kinase lck (p56lck). In T cells many activation events reduce the high constitutive p56lck expression levels typical for that lineage, and they induce the appearance of a 60-kDa lck species. We now demonstrate that in B cells exposed to EBV the at best low constitutive p56lck expression levels are rapidly and transiently up-regulated without generation of 60-kDa lck. lck-specific antisense oligonucleotides block p56lck induction and prevent subsequent B cell activation and immortalization whereas B cell activation by nononcogenic agents was unaffected. We propose that p56lck superinduction is a transformation prerequisite which signals entry into the oncogenic growth transformation process.

Cellular toxicity of sulfamethoxazole reactive metabolites--II. Inhibition of natural killer activity in human peripheral blood mononuclear cells

Based on the identification of intracellular esterase activity as one early target of sulfamethoxazole hydroxylamine (SMX-HA), we wished to determine if the metabolite affected immune functions which involve esterases. The natural killer (NK) activity of human peripheral blood mononuclear cells (PBMC) was assessed with a cell concentration fluorescence technique following exposure to SMX-HA. When K562 target cells were incubated (4 hr/37 degrees) with various ratios of untreated PBMC effector to K562 target cells (E:T), NK activity increased from 17.8 +/- 3.1% (mean +/- SEM; N = 12) at an E:T ratio of 5:1 to 46.2 +/- 2.0% at an E:T ratio of 40:1. Pretreatment of fresh PBMC with 0.1 to 1.0 mM SMX-HA produced a concentration-dependent inhibition of NK activity (E:T ratio 40:1) reaching approximately 80% at 1 mM SMX-HA. Maximum suppression of NK activity was completed within a 60-min pretreatment period with measurable inhibition detected within 30 min. The viability of effector cells was not affected by the metabolite during the pretreatment period. Therefore, the SMX-HA effects could not be directly attributed to decreased viability of the effector cells; they were irreversible and could be prevented by the inclusion of exogenous reduced glutathione (GSH) in a concentration-dependent manner. Given the important roles of NK cells in immune responsiveness and host resistance, our findings of rapid functional inactivation of the cytolytic effector function provide a possible link between idiosyncratic drug toxicity and drug effects directly on components of the immune system.

Cellular toxicity of sulfamethoxazole reactive metabolites--I. Inhibition of intracellular esterase activity prior to cell death

Reactive metabolites produced by oxidative metabolism of the parent compound are considered responsible for the toxicity of a number of drugs, including idiosyncratic reactions to sulfonamide antibiotics. Using sulfamethoxazole hydroxylamine (SMX-HA) as a model compound, we report the use of a pH-sensitive fluorescent probe, 2',7'-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF), to identify early subcellular targets of chemically synthesized, toxic drug metabolites in peripheral blood mononuclear cells. When toxicity was assessed with this probe immediately after a 2-hr drug challenge, SMX-HA produced a concentration-dependent decrease in cellular fluorescence which was not accompanied by the development of compromised cell membrane integrity until 18 hr later. Dissipation of pH gradients across the cell membrane with nigericin and monensin demonstrated that decreased intracellular pH was only a small component of SMX-HA-induced toxicity. Loading cells with BCECF 30 min prior to SMX-HA challenge produced only a 3% decrease in cellular fluorescence at an SMX-HA concentration of 1 mM, whereas addition of BCECF after drug challenge resulted in a 71% decrease in fluorescence, consistent with a direct drug effect on cellular esterase activity. This was confirmed by monitoring BCECF cleavage in cell lysates in the presence and absence of SMX-HA. These studies demonstrate that inhibition of cellular esterase activity accounted for the observed loss of cellular fluorescence after drug exposure. Since changes in cellular fluorescence at 2 hr correlated well with cell death at 18 hr, we conclude that SMX-HA inhibition of intracellular esterase activity is an early event in the process that terminates in metabolite-induced cell death.

Interactions between N-acetyl-p-benzoquinone imine and fluorescent calcium probes: implications for mechanistic toxicology

Intracellular free calcium ([Ca2+]i) homeostasis has been implicated as an early target in both cellular necrosis and apoptosis. In this study, we have used peripheral blood mononuclear cells (PBMC) as target cells to investigate the effects of several reactive metabolites associated with drug toxicity on [Ca2+]i in order to delineate further early events in cytotoxicity. Compounds implicated in both drug-induced necrosis (N-acetyl-p-benzoquinone imine; NAPQI) and drug hypersensitivity (sulfamethoxazole hydroxylamine; SMX-HA) were examined and their effects on [Ca2+]i compared with those of the T cell mitogen phytohemagglutinin (PHA; 1.5 micrograms/ml) and the calcium ionophore ionomycin (2.5 microM). PHA and ionomycin produced characteristic elevations in [Ca2+]i as monitored by an increase in the fluorescence of fluo-3-loaded cells. SMX-HA did not significantly affect [Ca2+]i at concentrations previously shown to be cytotoxic to PBMC (100 and 500 microM), suggesting that Ca2+ homeostasis is not an early target for SMX-HA toxicity. Addition of NAPQI (250 microM) to fluo-3-loaded cells produced a marked decrease in fluorescence which was not reversed by ionomycin. Conversely, addition of NAPQI to cells loaded with indo-1 resulted in a rapid increase in fluorescence. This effect, however, was found to be attributable to NAPQI addition per se rather than to an increase in [Ca2+]i. HPLC and fluorescence analysis of samples generated from the decomposition of NAPQI revealed the presence of several products which fluoresced intensely at the excitation/emission wavelength pairs of a number of fluorescent probes commonly used to monitor [Ca2+]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of IgE from a nonrearranged epsilon locus in cloned B-lymphoblastoid cells that also express IgM

During development, B lymphocytes have the ability to switch from synthesis of IgM to immunoglobulins of another isotype such as IgG, IgA, or IgE. This class switching mechanism has been shown to involve DNA rearrangement and concomitant deletion of intervening CH genes. In our report, an EBV-transformed B lymphoblastoid cloned cell line is described that simultaneously expressed and secreted both IgM and IgE. DNA analysis showed the (nonproductive) rearrangement of one allele to gamma and (productive) rearrangement of the other allele to mu. Germ-line arrangement of the C epsilon gene was preserved on both alleles.

Expression of IgE from a nonrearranged epsilon locus in cloned B-lymphoblastoid cells that also express IgM

During development, B lymphocytes have the ability to switch from synthesis of IgM to immunoglobulins of another isotype such as IgG, IgA, or IgE. This class switching mechanism has been shown to involve DNA rearrangement and concomitant deletion of intervening CH genes. In our report, an EBV-transformed B lymphoblastoid cloned cell line is described that simultaneously expressed and secreted both IgM and IgE. DNA analysis showed the (nonproductive) rearrangement of one allele to gamma and (productive) rearrangement of the other allele to mu. Germ-line arrangement of the C epsilon gene was preserved on both alleles.

Expression of glycolipid receptors to Shiga-like toxin on human B lymphocytes: a mechanism for the failure of long-lived antibody response to dysenteric disease

Fresh and transformed human B lineage cells were found to be sensitive to the cytotoxic action of Shiga-like toxin (SLT), a bacterial cytotoxin. The toxin was specifically bound by the glycolipids globotriosylceramide and galabiosylceramide expressed on the surface of sensitive cells. Mutant Daudi cells selected for resistance to SLT cytotoxicity (SLTR20) were deficient in SLT-binding glycolipids and failed to bind SLT to their surface, suggesting a role for these glycolipids in the mediation of SLT cytotoxicity. Of a number of normal and transformed lymphoid and myeloid cells screened for SLT sensitivity, only B lymphoid cells were susceptible to SLT action. Moreover, B lymphoid cells were the only cells expressing the SLT binding glycolipids. In vitro B cell activation studies with Epstein-Barr virus and pokeweed mitogen both indicated that the vast majority of SLT-sensitive B cells belong to the IgG and IgA committed subset, whereas most IgM and IgM/D producing cells were resistant to SLT toxicity. The selective elimination of IgG and IgA committed cells may explain the production of only IgM class anti-SLT antibodies in Shigella-infected humans leading to the failure of long-term immunity to dysenteric disease.

EBV utilizes a unique activation pathway for the transformation of human B cells

EBV growth-transforms primate B lymphocytes and directly causes mono/multiclonal B cell lymphomas in vulnerable hosts. In this report we demonstrate that the degree of B cell transformability is not quantitatively determined at the level of either the saturable, transformation-prerequisite virus receptors or of the actual viral cell entry process. Instead, post-receptor binding events [Na+/H+ exchange, Ca2+ flux, tyrosine phosphorylation of two proteins (55-60/130-140 kd)] were identified as critical determinants of transformability. The presence of competent virus in transformable cells was per se insufficient for transformation: blockade of Ca2+ fluxes (or the antiport) generates virus-loaded cells that express viral genes but remain untransformed. Delayed induction by ionomycin of appropriately sized Ca2+ fluxes ([Ca2+]i greater than 180 less than 400 nM) re-starts transformation processes in EGTA-blocked, virus-loaded cells, perhaps providing a model for the study of virus re-activation. Overall, EBV induces unique cellular activation events different from non-oncogenic lymphocyte mitogens/activators, and, given the oncogenic potential of transformed cells in susceptible hosts, we hypothesize that these events describe a novel oncogenic transformation pathway.

Concerted generation of Ig isotype diversity in human fetal bone marrow

The human fetal bone marrow B cell compartment of 14- to 21-wk gestational age was examined phenotypically and with respect to Ig H chain commitment and diversity. A dramatic expansion of fetal marrow B cell pools at 16- to 18-wk gestational age characterizes a rapid and concerted chain of differentiation events. Transiently up to 1/4 of nucleated marrow cells are CD20+/CD21+ cells which begin to express surface Ig other than IgM. Limiting dilution analysis of EBV-infected marrow cells delineated a virtually exclusive commitment to IgM production until 15 wk and the absolute and relative number of these cells were small (approximately 5% of comparable adult values). In parallel to the rapid increase in total B cell pools size, cells committed and able to secrete any of the five Ig isotypes are generated by 16-wk gestational age and by 18 wk the frequencies of these cells rapidly reach levels typical for adult peripheral tissue such as blood or lymph node. Fetal L chain diversity always anticipated that observed in adult serum. In addition to rising pool sizes and diverse IgH expression, EBV transformability is a major variable during this period of B cell development with up to 2/3 of B lineage cells transformable, about half of which are pre-B cells. By 21-wk gestational age transformable pre-B cells have disappeared and (as in adult tissue) approximately 10 to 20% of CD20+ cells are transformable. The rapid, concerted expression of full H chain diversity during a narrow period in fetal development is unique to marrow and implies a lymphopoietic process in a privileged site rather than an immunologic differentiation event. During this event, the relative proportions between the different IgH classes expressed, resembled that found in adult tissue, perhaps suggesting that B cell inherent programming rather than only antigenic forces determine heavy chain choice. The staggered expression, early in postnatal life, of IgH regions 3' of the C mu locus may reflect regulatory functions rather than inherent immaturity of the B lineage.

Properties and heterogeneity of human fetal pre-B cells transformed by EBV

A series of 75 EBV-transformed pre-B and B-cell lines from fetal bone marrow at 14 to 18 wk of gestation was cloned for phenotypic, functional and molecular genetic studies. B-cell type volume regulation in response to hypotonic stress, low level CD9 (BA2), and, perhaps biased by our use of EBV, functional EBV receptors with expression of CD21 (B2) determinants characterized the most immature cells detected. These "B-progenitors" contained EBV genomes, maintained Ig H and L chain (as well as TCR) constant region genes in germ-line configuration and did not express other B, T, or myeloid lineage-associated surface markers including CD20 and MHC class II determinants. Such cells may represent B progenitor cells preceding classical pre-B-lymphocytes in pathways of B cell differentiation. Reminiscent of Abelson virus-induced transformation of immature murine B cells, EBV transformability together with the above properties may be the earliest markers of B lineage commitment in man. The expression of MHC class II Ag, CD20, C mu-H and then L chain rearrangements and expression followed in less immature pre-B lymphocytes and permitted a classification of lines into discrete subgroups of increasing maturity. The physical organization of the H chain locus in a given line was a stable characteristic. However, fetal pre-B cell lines showed considerable intraclonal heterogeneity with respect to H chain gene expression and that of differentiation markers such as CD20. Subcloning experiments indicated that this heterogeneity reflected clonally stable expression patterns distributed among subclones in an all-or-none fashion. The induction, by IL-6, of L chain expression in some but not all of these clones was linked to the presence of C mu transcription products, consistent with a possible regulatory role of mu protein in L chain rearrangement and expression. Although pre-B cell differentiation likely follows inherent programming, external signals seem able to hasten development along prescribed, hierarchical differentiation pathways.

Concerted generation of Ig isotype diversity in human fetal bone marrow

The human fetal bone marrow B cell compartment of 14- to 21-wk gestational age was examined phenotypically and with respect to Ig H chain commitment and diversity. A dramatic expansion of fetal marrow B cell pools at 16- to 18-wk gestational age characterizes a rapid and concerted chain of differentiation events. Transiently up to 1/4 of nucleated marrow cells are CD20+/CD21+ cells which begin to express surface Ig other than IgM. Limiting dilution analysis of EBV-infected marrow cells delineated a virtually exclusive commitment to IgM production until 15 wk and the absolute and relative number of these cells were small (approximately 5% of comparable adult values). In parallel to the rapid increase in total B cell pools size, cells committed and able to secrete any of the five Ig isotypes are generated by 16-wk gestational age and by 18 wk the frequencies of these cells rapidly reach levels typical for adult peripheral tissue such as blood or lymph node. Fetal L chain diversity always anticipated that observed in adult serum. In addition to rising pool sizes and diverse IgH expression, EBV transformability is a major variable during this period of B cell development with up to 2/3 of B lineage cells transformable, about half of which are pre-B cells. By 21-wk gestational age transformable pre-B cells have disappeared and (as in adult tissue) approximately 10 to 20% of CD20+ cells are transformable. The rapid, concerted expression of full H chain diversity during a narrow period in fetal development is unique to marrow and implies a lymphopoietic process in a privileged site rather than an immunologic differentiation event. During this event, the relative proportions between the different IgH classes expressed, resembled that found in adult tissue, perhaps suggesting that B cell inherent programming rather than only antigenic forces determine heavy chain choice. The staggered expression, early in postnatal life, of IgH regions 3' of the C mu locus may reflect regulatory functions rather than inherent immaturity of the B lineage.

Properties and heterogeneity of human fetal pre-B cells transformed by EBV

A series of 75 EBV-transformed pre-B and B-cell lines from fetal bone marrow at 14 to 18 wk of gestation was cloned for phenotypic, functional and molecular genetic studies. B-cell type volume regulation in response to hypotonic stress, low level CD9 (BA2), and, perhaps biased by our use of EBV, functional EBV receptors with expression of CD21 (B2) determinants characterized the most immature cells detected. These "B-progenitors" contained EBV genomes, maintained Ig H and L chain (as well as TCR) constant region genes in germ-line configuration and did not express other B, T, or myeloid lineage-associated surface markers including CD20 and MHC class II determinants. Such cells may represent B progenitor cells preceding classical pre-B-lymphocytes in pathways of B cell differentiation. Reminiscent of Abelson virus-induced transformation of immature murine B cells, EBV transformability together with the above properties may be the earliest markers of B lineage commitment in man. The expression of MHC class II Ag, CD20, C mu-H and then L chain rearrangements and expression followed in less immature pre-B lymphocytes and permitted a classification of lines into discrete subgroups of increasing maturity. The physical organization of the H chain locus in a given line was a stable characteristic. However, fetal pre-B cell lines showed considerable intraclonal heterogeneity with respect to H chain gene expression and that of differentiation markers such as CD20. Subcloning experiments indicated that this heterogeneity reflected clonally stable expression patterns distributed among subclones in an all-or-none fashion. The induction, by IL-6, of L chain expression in some but not all of these clones was linked to the presence of C mu transcription products, consistent with a possible regulatory role of mu protein in L chain rearrangement and expression. Although pre-B cell differentiation likely follows inherent programming, external signals seem able to hasten development along prescribed, hierarchical differentiation pathways.

Fluorescence-based viability assay for studies of reactive drug intermediates

Studies of drug toxicity, toxicologic structure-function relationships, screening of idiosyncratic drug reactions, and a variety of cytotoxic events and cellular functions in immunology and cell biology require the sensitive and rapid processing of often large numbers of cell samples. This report describes the development of a high-sensitivity, high-throughput viability assay based on (a) the carboxyfluorescein derivative 2'-7'-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF) as a vital dye, (b) instrumentation capable of processing multiple small (less than 100 cells) samples, and (c) a 96-well unidirectional vacuum filtration plate. Double staining of cultured peripheral blood mononuclear cells with BCECF and propidium iodide (PI) showed no overlap between PI+ (nonviable) and BCECF+ (viable) cells by flow cytometric analysis. Optimal conditions were developed for dye loading and minimizing physical cell damage and fluorescence quench during the assay procedure. The ratio of BCECF fluorescence to internal standard fluorescent particles was linear from 40 to greater than 20,000 cells with a signal:noise ratio of approximately 3 at 40 cells/well. Sulfamethoxazole hydroxylamine (SMX-HA) was used as a model toxic drug metabolite to explore the validity of the BCECF procedure. SMX-HA, but not its parent compound sulfamethoxazole, resulted in a dose dependent loss of cellular fluorescence and the parallel accumulation of PI+ nonviable cells. When compared to the currently used tetrazolium dye reduction viability assay, the BCECF method was 3-fold more sensitive, greater than 10-fold faster, and required 1/10-1/100 the cell numbers.

Rapid amplification of complementary DNA from small amounts of unfractionated RNA

We have combined, in a rapid and straightforward manner, the synthesis and subsequent amplification of individual cDNA sequences from microgram quantities of unfractionated total RNA. Taq1 polymerase, a thermostable DNA polymerase, and Moloney murine leukemia virus (MMLV) reverse transcriptase share similar buffer conditions; these reactions can be performed sequentially, in a single tube, without the need for purification or changes of buffer after the synthesis of cDNA. In this way, nonspecific losses of material are minimized and the required number of cells is reduced. Cell numbers, particularly from human tissues, can be limiting; the requirement for only small amounts of unfractionated RNA makes possible the isolation and characterization of cDNAs from biological materials available in limited quantities. As a demonstration system, we report the rapid synthesis and amplification of cDNA sequences corresponding to the first exon of human immunoglobulin E (IgE). MMLV reverse transcriptase is used with specific (i.e., IgE) or generic (i.e., oligo-[dT(12-18)]) oligomers to prime first strand cDNA synthesis from unfractionated RNA isolated from a human myeloma line, U-266. The necessary primers, deoxynucleotides and Taq1 polymerase, required for second strand cDNA synthesis and the subsequent logarithmic amplification process, are then added to the reaction mixture. This technique provides a useful means of characterizing expressed and processed gene transcripts.

Clonal and molecular characteristics of the human IgE-committed B cell subset

We have followed the pathway of the IgE-committed B lymphocyte from fresh, unstimulated peripheral blood, through EBV activation, transformation, and eventual cloning. Using cell sorting in conjunction with limiting dilution culture systems, we found that: (a) cells that are selected in the cell sorter and secrete IgE in culture are sIgM+/sIgD+. They secrete all three isotypes after EBV activation and continue to do so stably in culture; (b) individual IgE+ cells in culture coproduce IgM, IgD, and IgE and cytoplasmic Ig of each isotype can be detected in single cells; (c) no rearrangement was observed of VDJ to epsilon in any of six lines tested. DNA between the rearranged VDJ-mu and -epsilon appears to be overall intact, including a region 10.5 kb upstream and 18 kb downstream of the 2-kb epsilon coding region and; (d) mRNA of mu and epsilon species is of normal and comparable size. In contrast to IgG- and IgA-producing clones, multiple isotype expression appears to be both frequent and stable in cells committed to IgE production. We propose that IgE-committed cells represent a unique B cell sublineage whose differentiation pathway may be more strictly regulated than that of other isotypes with regard to the signals required for classical, deletional switch recombination that has been observed in rare IgE-producing myeloma cell lines.

Human IgE response: virus-activated IgE secretors are interleukin-2-dependent cells

The activation of human IgE-secreting B lymphocytes was difficult until the use of low cell density limiting dilution cultures, which are more efficient and eliminate regulatory growth restraints, became possible. The transformation of IgE-producing cells by Epstein-Barr virus unexpectedly required the presence of small supplements of mature T lymphocytes early in culture. Interleukin 2 (IL2, 10 U/ml) was able to completely replace T-cell supplements when added during a brief (1-2 cell cycles) but critical period, 5-8 days after infection with the virus. The observation that IgE-committed B cells are principally able to express receptors for and respond to IL2 is of experimental utility and implies the possibility that this T-cell product could be part of the complex T-cell controls which govern IgE-committed B cells.

Extracellular nucleotide catabolism in human B and T lymphocytes. The source of adenosine production

Extracellular nucleotide degradation was studied in intact human B and T lymphocyte subpopulations and in lymphoblastoid cell lines. Cells of B lymphocyte lineage showed high nucleotide degrading activity, whereas T lymphocytes were unable to degrade extracellular nucleotides. The external surface of B cells contained active sites of ecto-triphosphonucleotidase (ecto-ATPase), ecto-diphosphonucleotidase (ecto-ADPase), and ecto-monophosphonucleotidase (ecto-AMPase). The expression of all three ectoenzyme activities seemed closely associated with B cell development. ATPase and ADPase activities increase continuously during B cell maturation, ecto-AMPase activity, on the other hand, reaches maximal activity in late pre-B cells. These results combined with our previous studies of intracellular ATP catabolism (Barankiewicz, J., and Cohen, A. (1984) J. Biol. Chem. 259, 15178-15181) provide evidence that extracellular ATP catabolism may represent exclusive source for adenosine in lymphocytes. It is suggested that adenosine may serve as a means of communication between B and T cells in lymphoid organs, B lymphocytes being the sole producers of adenosine and T lymphocytes being the recipients of this signal.

Activation of human B lymphocytes by 8' substituted guanosine derivatives

The 8-substituted guanosine derivatives (8-sGs), mercaptoguanosine and bromoguanosine, are shown to induce immunoglobulin production and proliferation in a subset of normal human B lymphocytes. Limiting dilution analysis indicated that the 8-sG-responsive B cell pool is approximately 10 times larger than that activated by pokeweed mitogen (PWM), 10 times smaller than that activated by Epstein-Barr virus (EBV), and contains approximately equal proportions of cells committed to the expression of IgG, IgA or IgM isotypes. Although some B cells seem able to respond to 8-sGs in the absence of T helper cells, maximal immunoglobulin production is only observed in the presence of T cells. The 8-sG response pattern of human B lymphocytes appeared similar but not identical to that reported for rodent cells. The mitogenic 8-sGs are unique activators as they bypass surface membrane interactions obligatory for other agents including anti-IgM, Staphylococcus aureus particles, PWM, and EBV.

IgE-enhancing activity directly and selectively affects activated B cells: evidence for a human IgE differentiation factor

T cells from highly atopic individuals spontaneously secrete in vitro a factor that specifically induces IgE synthesis from normal human B cells. We investigated the effects of such T cell supernatants derived from atopic individuals (TCSN-A) on functionally distinct B cell subsets to determine at what developmental stage B cells become responsive to this IgE-enhancing activity. B cells from normal and allergic donors were separated into subsets of small resting and large activated cells by density centrifugation or unit gravity sedimentation. When stimulated by TCSN-A, large activated B cells made more IgE than small resting B cells. The difference was as much as 3300% in comparing these subsets from allergic donors. Similarly, resting B cells stimulated by Staphylococcus aureus Cowan I (SAC) made 52 to 125% more IgE in response to TCSN-A than unstimulated small resting B cells. However, IgE production from large B cells, already activated in vivo, was not enhanced by the addition of SAC. Notably, the IgE level synthesized by in vivo large activated B cells from allergic persons was markedly greater than that seen with similar cells from normal donors, whereas resting B cells purified from allergic and normal donors produced comparable levels of IgE in response to TCSN-A. These results suggest that this enhancing activity functions as an IgE differentiation factor for activated B cells. This was further confirmed by the effects of TCSN-A on the IgM- and IgE-secreting EBV-transformed human B cell line K1D5. TCSN-A specifically enhanced IgE synthesis from these cells; TCSN from normal donors, IL 2, IFN-gamma, and BCGF did not. These results confirm that this activity functions as an IgE-specific differentiation factor, directly influencing activated B cells to synthesize IgE.

IgE-enhancing activity directly and selectively affects activated B cells: evidence for a human IgE differentiation factor

T cells from highly atopic individuals spontaneously secrete in vitro a factor that specifically induces IgE synthesis from normal human B cells. We investigated the effects of such T cell supernatants derived from atopic individuals (TCSN-A) on functionally distinct B cell subsets to determine at what developmental stage B cells become responsive to this IgE-enhancing activity. B cells from normal and allergic donors were separated into subsets of small resting and large activated cells by density centrifugation or unit gravity sedimentation. When stimulated by TCSN-A, large activated B cells made more IgE than small resting B cells. The difference was as much as 3300% in comparing these subsets from allergic donors. Similarly, resting B cells stimulated by Staphylococcus aureus Cowan I (SAC) made 52 to 125% more IgE in response to TCSN-A than unstimulated small resting B cells. However, IgE production from large B cells, already activated in vivo, was not enhanced by the addition of SAC. Notably, the IgE level synthesized by in vivo large activated B cells from allergic persons was markedly greater than that seen with similar cells from normal donors, whereas resting B cells purified from allergic and normal donors produced comparable levels of IgE in response to TCSN-A. These results suggest that this enhancing activity functions as an IgE differentiation factor for activated B cells. This was further confirmed by the effects of TCSN-A on the IgM- and IgE-secreting EBV-transformed human B cell line K1D5. TCSN-A specifically enhanced IgE synthesis from these cells; TCSN from normal donors, IL 2, IFN-gamma, and BCGF did not. These results confirm that this activity functions as an IgE-specific differentiation factor, directly influencing activated B cells to synthesize IgE.

Volume regulation of natural killer cells under hypotonic stress: comparison with T and B cell subpopulations

In response to hypotonic stress, human T and B cells vary in the ability to adjust their volume. Whereas T cells exhibit a regulatory volume decrease (RVD) under these conditions, B cells do not. We studied the ability of peripheral blood-derived natural killer (NK) cells to regulate their volume in this way. Percoll density gradient purified NK subpopulation showed variable RVD which suggested the presence of mixtures of regulatory and non-regulatory cells within these subgroups. Further purification by flow cytometry into Leu 7+ and Leu 11+ cells showed that these NK cells displayed RVD similar to thymocytes but distinct from B cells and more mature T cells. These data support the hypothesis that NK cells may be derived from T cell precursors which, upon differentiation to NK cells, retain the RVD characteristic of pre-T cells. This finding may also be useful in further characterizing neoplastic clones which display NK-like activity but phenotypic heterogeneity.

Epstein-Barr virus-induced IgE production in limiting dilution cultures of normal human B cells

The induction of in vitro IgE production in human B cells from normal, nonatopic donors has been difficult and somewhat controversial. We report that IgE production is consistently observed in limiting dilution cultures of in vitro Epstein-Barr virus (EBV)-infected normal human B lymphocytes. The frequency of IgE-committed, EBV-responsive cells ranged from 1/810 to 1/10 000 B lymphocytes, and it was similar in peripheral (blood, tonsil) and central (bone marrow) tissue sites. Poisson distribution analysis of these limiting dilution cultures suggested that IgE-committed B cells comprise 0.1-1% of all EBV-responsive B lymphocytes.

Phenotype, frequency, and EBV responsiveness of human marrow B and pre-B cells

We have purified subpopulations of B lineage cells from human adult (rib) bone marrow by cell sorting and panning. Limiting dilution analysis was then used for a clonal analysis of cells able to secrete IgG, IgA, or IgM spontaneously or after infection with EBV. Nonproliferating, high rate IgG or IgA producers occurred at frequencies of about one per 1000 marrow mononuclear cells. Their frequency and Ig production was unaffected by EBV, and they appeared not to express EBNA after exposure to EBV. These cells were Ia+, B1+, and over 85% expressed sIg of the IgM/D (up to 75%) and/or IgG/A isotypes (40 to 60%). B cells committed to the secretion of IgM represent 2 to 10% of marrow B lymphocytes. They were found to be Ia+/B1+/B2+/CALLA- and C3b receptor (CR3)-cells, and most (greater than 90%) required infection with EBV and proliferation to develop into IgM-producing lymphocytes. Thirty to 40% of these cells did not express Ig (H or L chain) on their surface, and therefore resembled pre-B cells at the beginning of the 4- to 5-wk culture period. Proliferating pre-B cells from adult human marrow have been described, but their conversion into IgM-producing cells has not been formally demonstrated. Although EBV induces IgM production, the expression of EBNA, and several rounds of cell division in these cells, the induction of stable (greater than 5 wk) growth transformation represents a rare event in these pre-B cells: in several thousand limiting dilution wells, not a single culture of sIg-cells showed stable growth transformation. The dichotomy between EBV-induced high-rate IgM responses and absent growth transformation discriminates activation and transformation as distinct aspects of EBV-induced B cell "responses", and suggests that cellular properties play critical roles for viral transformation. We propose a model in which cellular target genes for transforming sequences in the EBV genome are transiently expressed during B cell differentiation.

Phenotype, frequency, and EBV responsiveness of human marrow B and pre-B cells

We have purified subpopulations of B lineage cells from human adult (rib) bone marrow by cell sorting and panning. Limiting dilution analysis was then used for a clonal analysis of cells able to secrete IgG, IgA, or IgM spontaneously or after infection with EBV. Nonproliferating, high rate IgG or IgA producers occurred at frequencies of about one per 1000 marrow mononuclear cells. Their frequency and Ig production was unaffected by EBV, and they appeared not to express EBNA after exposure to EBV. These cells were Ia+, B1+, and over 85% expressed sIg of the IgM/D (up to 75%) and/or IgG/A isotypes (40 to 60%). B cells committed to the secretion of IgM represent 2 to 10% of marrow B lymphocytes. They were found to be Ia+/B1+/B2+/CALLA- and C3b receptor (CR3)-cells, and most (greater than 90%) required infection with EBV and proliferation to develop into IgM-producing lymphocytes. Thirty to 40% of these cells did not express Ig (H or L chain) on their surface, and therefore resembled pre-B cells at the beginning of the 4- to 5-wk culture period. Proliferating pre-B cells from adult human marrow have been described, but their conversion into IgM-producing cells has not been formally demonstrated. Although EBV induces IgM production, the expression of EBNA, and several rounds of cell division in these cells, the induction of stable (greater than 5 wk) growth transformation represents a rare event in these pre-B cells: in several thousand limiting dilution wells, not a single culture of sIg-cells showed stable growth transformation. The dichotomy between EBV-induced high-rate IgM responses and absent growth transformation discriminates activation and transformation as distinct aspects of EBV-induced B cell "responses", and suggests that cellular properties play critical roles for viral transformation. We propose a model in which cellular target genes for transforming sequences in the EBV genome are transiently expressed during B cell differentiation.

Lymphocyte function in human bone marrow. III. Isotype commitment, metabolic and secretory characteristics of immunoglobulin producing cells

We have examined the functional and metabolic properties of immunoglobulin (Ig)-secreting cells in adult (rib) bone marrow, the tissue which provides the major proportion of serum Igs. In the absence of polyclonal activators, high rate Ig production (1-2 micrograms/day/10(6) marrow mononuclear cells) was sustained from the beginning of culture throughout 2 weeks and then declined. Ten percent of the Ig secreted was of the IgM isotype and IgG/A made up the remainder at equal proportions. Infection of marrow cells with Epstein-Barr virus (EBV) induced the production of large amounts of IgM, but virtually all IgG/A-committed cells were refractory to stimulation with EBV. Both EBV-induced and the "spontaneous" Ig production was inhibited by cycloheximide, but only EBV-induced IgM production was blocked by hydroxyurea and gamma-irradiation. The polyclonal activators PHA and PWM induce suppressor-T-cell activity in marrow cultures. This suppressor function involves nonproliferating cells which acquire suppressive activity 3-4 days after mitogenic activation. Prednisolone and cyclosporine A modulate Ig production in cultures of peripheral lymphocytes but had no effect on Ig secretion in marrow cell cultures. This observation was reminiscent of the absent or at best marginal short-term effects on in vivo serum Ig levels which is typical for these drugs. Our observations suggest that the marrow Ig-producing B-lymphoid cell compartment shows major differences to other tissue sites with respect to properties of the Ig-secreting cells the immunoregulatory activities able to control their function, and the response of these cells to clinically important drugs.

Limiting dilution analysis of the B cell compartment in human bone marrow

Mononuclear cells (MNC) obtained from adult rib specimen were investigated for their capacity to produce immunoglobulin (Ig) in vitro. Using limiting dilution analysis 3 populations of B lineage cells could be distinguished. The first produces Ig in culture without any intentional activation. These cells are strictly nonproliferating and sustain extraordinary secretory rates of 5 X 10(7)-10 X 10(7) molecules IgG, IgA or IgM/cell/h for at least 2 weeks. They occur at frequencies of 1 X 10(-4)-10 X 10(-4) (marrow MNC) or represent 1-5% of marrow B cells. Following exposure to infectious Epstein-Barr virus (EBV), these cells do not (a) proliferate, (b) express EBV-determined nuclear antigens (EBNA), (c) enhance their secretory rates or (d) show secretory activity for prolonged time. These cells are therefore EBV resistant. If these cells produced their antibody at similar rates in vivo, then their frequencies would suggest that they could provide up to 2/3 of daily synthetic rates for IgG and IgA and 20-30% of the daily IgM production. The second population of marrow B cells is exclusively committed to IgM production. Following exposure to EBV these cells proliferate, express EBNA and begin to secrete IgM. The third population represents 90% of marrow B cells. In our hands, these cells are unable to produce Ig in vitro.

Heterogeneity of EBV-transformable human B lymphocyte populations

Although most human B cells express receptors for Epstein Barr virus (EBV), few (usually less than 1%) are readily transformed into B lymphoblastoid cell lines after exposure to EBV. Transformable cells previously have been found to be mostly resting B lymphocytes. We recently developed a limiting dilution culture system which permits the growth of EBV-transformed B lymphocytes with high efficiency. Because in this system up to over 30% of peripheral blood- or tonsil-derived B cells respond to EBV, we re-examined the properties of EBV-transformable cells. Frequencies of transformable lymphocytes were determined by Poisson analysis. EBV-susceptible B cells committed to IgM, IgG, or IgA secretion were found to occur in the range of 3 to 27, 0.1 to 6, and 0.1 to 5 per 100 B cells, respectively. Under our culture conditions, a major proportion of the IgM-committed cells derived from large lymphocytes which appeared to have entered the cell cycle. This population contains most of the EBV-responsive cells detected and, therefore, most of the additional cells responding in our culture system. In contrast, precursors of IgG- or IgA-producing lymphoblast lines were small cells with DNA contents typical for the G0/G1 phases of the cell cycle. Anti-immunoglobulin antibodies were used in panning experiments to separate B cell subpopulations which expressed different immunoglobulin isotypes on their surface. In limiting dilution cultures of these purified B lymphocytes subsets, it was found that virtually all precursors of IgM-producing cell lines expressed surface IgM (sIgM) before their infection and transformation by EBV. The "cloning efficiency" of positively selected, large sIgM+ cells approached 100%. In contrast, sIgG or sIgA were found only on cells committed to the production of IgG or IgA, respectively. The expression of sIgD was examined by using sequential panning procedures. Virtually all IgM-committed lymphocytes and a subset of cells committed to IgA secretion were found among the sIgD+ cells. The majority of cells committed to IgA production and all IgG-committed cells were found in the sIgD- B cell population. Our findings indicate that the EBV-susceptible B cell subset of normal lymphocytes is heterogeneous with respect to cell size, cell cycle, sIg determinants, and efficiency of transformation. On the basis of our findings and previous reports, we propose a model in which transformability is a B cell-inherent property. Factors unrelated to the virus but present in our culture system appear responsible for the enhanced vulnerability to viral transformation in some cells which entered into the cell cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Heterogeneity of EBV-transformable human B lymphocyte populations

Although most human B cells express receptors for Epstein Barr virus (EBV), few (usually less than 1%) are readily transformed into B lymphoblastoid cell lines after exposure to EBV. Transformable cells previously have been found to be mostly resting B lymphocytes. We recently developed a limiting dilution culture system which permits the growth of EBV-transformed B lymphocytes with high efficiency. Because in this system up to over 30% of peripheral blood- or tonsil-derived B cells respond to EBV, we re-examined the properties of EBV-transformable cells. Frequencies of transformable lymphocytes were determined by Poisson analysis. EBV-susceptible B cells committed to IgM, IgG, or IgA secretion were found to occur in the range of 3 to 27, 0.1 to 6, and 0.1 to 5 per 100 B cells, respectively. Under our culture conditions, a major proportion of the IgM-committed cells derived from large lymphocytes which appeared to have entered the cell cycle. This population contains most of the EBV-responsive cells detected and, therefore, most of the additional cells responding in our culture system. In contrast, precursors of IgG- or IgA-producing lymphoblast lines were small cells with DNA contents typical for the G0/G1 phases of the cell cycle. Anti-immunoglobulin antibodies were used in panning experiments to separate B cell subpopulations which expressed different immunoglobulin isotypes on their surface. In limiting dilution cultures of these purified B lymphocytes subsets, it was found that virtually all precursors of IgM-producing cell lines expressed surface IgM (sIgM) before their infection and transformation by EBV. The "cloning efficiency" of positively selected, large sIgM+ cells approached 100%. In contrast, sIgG or sIgA were found only on cells committed to the production of IgG or IgA, respectively. The expression of sIgD was examined by using sequential panning procedures. Virtually all IgM-committed lymphocytes and a subset of cells committed to IgA secretion were found among the sIgD+ cells. The majority of cells committed to IgA production and all IgG-committed cells were found in the sIgD- B cell population. Our findings indicate that the EBV-susceptible B cell subset of normal lymphocytes is heterogeneous with respect to cell size, cell cycle, sIg determinants, and efficiency of transformation. On the basis of our findings and previous reports, we propose a model in which transformability is a B cell-inherent property. Factors unrelated to the virus but present in our culture system appear responsible for the enhanced vulnerability to viral transformation in some cells which entered into the cell cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential regulation of activation, clonal expansion, and antibody secretion in human B cells

Limiting dilution analysis, hemolytic plaque assay, and ELISA procedures were used to study the recruitment, clonal expansion, and antibody secretion in human TNP-specific B cells activated in the presence of TNP-ovalbumin (TNP-OA), pokeweed mitogen (PWM), or regulatory T cells. TNP-OA-responsive, hapten-specific PFC precursor cells occupy approximately 0.5% of all sIgM+/sIgD+ B cells in cord blood, bone marrow, peripheral blood, and tonsil. The PWM-responsive, hapten-specific PFC precursor pool is 70 to 90% smaller and does not express sIgD. Antigen-reactive B cells go through a minimum of three divisions in culture (six to nine PFC per clone), and antibody secretory rates of about 10(4) molecules IgM/cell/hr are achieved. In contrast, PWM-induced clone sizes were at least 60 PFC per clone, with antibody secretory rates of approximately 6 to 7 X 10(4) molecules IgM/cell/hr. Addition of high-dose carrier-primed suppressor T cells to limit dilution cultures reduced PFC precursor cell recruitment by up to 99%. However, in the few clones escaping from suppression, both clonal expansion and antibody secretory rates were much higher than in suppressor cell-free cultures, generating 30 to 60% of the antibody secreted in controls but with consequently much more restricted clonal diversity. When limiting dilution cultures were compared with standard microcultures of 2 X 10(5) cells, both clonal expansion and antibody secretory rates were much lower than expected, with a culture efficiency calculated to be 10 to 20% of that in low-density cultures. Our data suggest that the B cell subsets activated by antigen and by mitogen differ in their abilities for clonal expansion and antibody secretion. The hapten-specific and -responsive B cell family is expressed early in ontogeny, and in adults it is distributed evenly throughout the body. These limiting dilution experiments revealed that the primary effect of regulatory T cells is a drastic reduction in clonal diversity, and much less a mere reduction in overall response magnitude.

Differential regulation of activation, clonal expansion, and antibody secretion in human B cells

Limiting dilution analysis, hemolytic plaque assay, and ELISA procedures were used to study the recruitment, clonal expansion, and antibody secretion in human TNP-specific B cells activated in the presence of TNP-ovalbumin (TNP-OA), pokeweed mitogen (PWM), or regulatory T cells. TNP-OA-responsive, hapten-specific PFC precursor cells occupy approximately 0.5% of all sIgM+/sIgD+ B cells in cord blood, bone marrow, peripheral blood, and tonsil. The PWM-responsive, hapten-specific PFC precursor pool is 70 to 90% smaller and does not express sIgD. Antigen-reactive B cells go through a minimum of three divisions in culture (six to nine PFC per clone), and antibody secretory rates of about 10(4) molecules IgM/cell/hr are achieved. In contrast, PWM-induced clone sizes were at least 60 PFC per clone, with antibody secretory rates of approximately 6 to 7 X 10(4) molecules IgM/cell/hr. Addition of high-dose carrier-primed suppressor T cells to limit dilution cultures reduced PFC precursor cell recruitment by up to 99%. However, in the few clones escaping from suppression, both clonal expansion and antibody secretory rates were much higher than in suppressor cell-free cultures, generating 30 to 60% of the antibody secreted in controls but with consequently much more restricted clonal diversity. When limiting dilution cultures were compared with standard microcultures of 2 X 10(5) cells, both clonal expansion and antibody secretory rates were much lower than expected, with a culture efficiency calculated to be 10 to 20% of that in low-density cultures. Our data suggest that the B cell subsets activated by antigen and by mitogen differ in their abilities for clonal expansion and antibody secretion. The hapten-specific and -responsive B cell family is expressed early in ontogeny, and in adults it is distributed evenly throughout the body. These limiting dilution experiments revealed that the primary effect of regulatory T cells is a drastic reduction in clonal diversity, and much less a mere reduction in overall response magnitude.

Lymphocyte function in human bone marrow. II. Characterization of an interleukin 2-sensitive T precursor-cell population

In the present study of human bone marrow lymphocytes, we analyze a newly recognized population of T suppressor-cell precursors which are found in marrow only and which have the potential to inhibit immunoglobulin (Ig) production in vitro. Following exposure to interleukin 2 (IL2), suppressor precursors acquire E receptor, T3 determinants, suppressor function, and lectin responsiveness. To distinguish this population within the framework of T-cell ontogeny, it was compared to a previously described population of thymus-dependent helper T-cell precursors which express helper function following exposure to thymus-derived mediators. The two populations are completely distinct and can be separated on density gradients. Suppressor precursors expressed T8 and TAC (IL2-receptor) antigens prior to in vitro induction with IL2. The thymic hormone-dependent cells expressed T4 but not T8 or TAC determinants. In two patients with severe combined immunodeficiency disease (SCID), IL2-responsive precursor cells appeared only late after thymus epithelium transplantation, perhaps best explained by a model in which thymus-dependent differentiation pathways precede, induce, or seed pathways of extra-thymic T-cell differentiation. The large pool size of over 10(11) suppressor and helper precursor cells present in adult bone marrow suggests that these populations may play an important role in immune homeostasis.

Lymphocyte function in human bone marrow. I. Characterization of two T cell populations regulating immunoglobulin secretion

We analyzed the regulation of immunoglobulin (Ig) production in short-term cultures of human (rib) bone marrow cells. In contrast to blood or tonsil cell cultures, large quantities of IgG and IgA, but not IgM, were secreted by unstimulated marrow cells. The addition of pokeweed mitogen or phytohemagglutinin resulted in the suppression of this Ig secretion. Both mitogens induced the production of high levels of interleukin 2 (IL 2) in marrow cultures, and the addition of IL 2 alone mimicked the suppressive effect of mitogens. Incubation of marrow cells with Epstein Barr virus resulted in enhanced Ig secretion, primarily of the IgM isotype. The addition of mitogen or IL 2 suppressed Ig production in these cultures as well. The mitogen-induced suppression of Ig secretion in stimulated or unstimulated marrow cultures was inhibited by the monoclonal anti-TAC (IL 2 receptor) antibody. Cell separation experiments indicated that the induction of suppressor activity in marrow cultures involved two distinct populations of marrow-resident T lineage cells. The first population responds to activation by mitogens with the production of IL 2. This population has a surface phenotype appropriate for helper T cells. The second T cell population expresses T8 and TAC determinants. These cells acquire suppressor cell activity after exposure to IL 2. The expression of suppressor function does not require additional (e.g., mitogenic) activation signals. The IL 2-dependent marrow suppressor T cells represent a newly recognized T lymphocyte subset. The regulatory pathway delineated may be important for the regulation of antibody formation in bone marrow, the major site of Ig production in man.

Lymphocyte function in human bone marrow. I. Characterization of two T cell populations regulating immunoglobulin secretion

We analyzed the regulation of immunoglobulin (Ig) production in short-term cultures of human (rib) bone marrow cells. In contrast to blood or tonsil cell cultures, large quantities of IgG and IgA, but not IgM, were secreted by unstimulated marrow cells. The addition of pokeweed mitogen or phytohemagglutinin resulted in the suppression of this Ig secretion. Both mitogens induced the production of high levels of interleukin 2 (IL 2) in marrow cultures, and the addition of IL 2 alone mimicked the suppressive effect of mitogens. Incubation of marrow cells with Epstein Barr virus resulted in enhanced Ig secretion, primarily of the IgM isotype. The addition of mitogen or IL 2 suppressed Ig production in these cultures as well. The mitogen-induced suppression of Ig secretion in stimulated or unstimulated marrow cultures was inhibited by the monoclonal anti-TAC (IL 2 receptor) antibody. Cell separation experiments indicated that the induction of suppressor activity in marrow cultures involved two distinct populations of marrow-resident T lineage cells. The first population responds to activation by mitogens with the production of IL 2. This population has a surface phenotype appropriate for helper T cells. The second T cell population expresses T8 and TAC determinants. These cells acquire suppressor cell activity after exposure to IL 2. The expression of suppressor function does not require additional (e.g., mitogenic) activation signals. The IL 2-dependent marrow suppressor T cells represent a newly recognized T lymphocyte subset. The regulatory pathway delineated may be important for the regulation of antibody formation in bone marrow, the major site of Ig production in man.

Reconstitution of nude mouse T cell function in vivo: IL 2-independent effect of human T cells

The i.p. injection of 1 to 5 X 10(6) heavily irradiated human T lymphocytes resulted in the lasting reconstitution of T cell functions in young mice bearing the nu/nu mutation. IgM and IgG responses to immunization with sheep red cells or ovalbumin, splenic lectin responses, and the expression of easily detectable Thy-1 determinants on up to 20% of spleen cells could be documented for several months after the injection of human cells. Only a narrow cell dose range was effective. Injection of larger cell numbers not only failed to induce immune reconstitution but also resulted in the development of resistance to subsequent treatments. Only mature T cells, but not thymocytes, could induce nude mouse T cell development. Lymphoblasts from one patient with acute T cell leukemia consistently immune-reconstituted nude recipients. These cells were completely unable to produce IL 2 in vitro. In contrast, the IL 2-producing T cell line Jurkat was ineffective, indicating that the abilities to produce IL 2 and to induce nude mouse T cell development are independent. In an extension of earlier models of the nude mouse immune defect, two distinct T precursor cell pools are proposed as the major components of an extrathymic differentiation pathway. As an adequate trigger of differentiation, interaction with thymus-processed T cells guides the development of precursors in the first cell pool towards populating the second IL 2-responsive pool of T precursor cells.

Reconstitution of nude mouse T cell function in vivo: IL 2-independent effect of human T cells

The i.p. injection of 1 to 5 X 10(6) heavily irradiated human T lymphocytes resulted in the lasting reconstitution of T cell functions in young mice bearing the nu/nu mutation. IgM and IgG responses to immunization with sheep red cells or ovalbumin, splenic lectin responses, and the expression of easily detectable Thy-1 determinants on up to 20% of spleen cells could be documented for several months after the injection of human cells. Only a narrow cell dose range was effective. Injection of larger cell numbers not only failed to induce immune reconstitution but also resulted in the development of resistance to subsequent treatments. Only mature T cells, but not thymocytes, could induce nude mouse T cell development. Lymphoblasts from one patient with acute T cell leukemia consistently immune-reconstituted nude recipients. These cells were completely unable to produce IL 2 in vitro. In contrast, the IL 2-producing T cell line Jurkat was ineffective, indicating that the abilities to produce IL 2 and to induce nude mouse T cell development are independent. In an extension of earlier models of the nude mouse immune defect, two distinct T precursor cell pools are proposed as the major components of an extrathymic differentiation pathway. As an adequate trigger of differentiation, interaction with thymus-processed T cells guides the development of precursors in the first cell pool towards populating the second IL 2-responsive pool of T precursor cells.

Carbamycholine modulation of E-rosette formation: identification of nicotinic acetylcholine receptors on a subpopulation of human T lymphocytes

We previously suggested that a population of T-suppressor cells carries acetylcholine receptors which may be involved in the regulation of the immune response. To identify cholinergic receptors on human T lymphocytes, we investigated the effects of carbachol, a cholinergic agonist, on E-rosette formation. Preincubation of normal human peripheral blood cells with carbachol resulted in a 30-40% reduction in numbers of E rosette-forming cells. Carbachol-induced inhibition of E-rosette formation was dose-dependent, temperature dependent, and reversible. The drug effects appeared to be mediated through a nicotinic acetylcholine receptor since d-tubocurarine (but not atropine) abrogated its activity. The expression of nicotinic receptors on a subset of human T cells may play an important role in the pathogenesis of certain diseases such as myasthenia gravis.

Volume regulation by human lymphocytes: characterization of the ionic basis for regulatory volume decrease

The mechanism of volume regulation in hypotonic media was analysed in human peripheral blood mononuclear (PBM) cells. Electronic cell sizing showed that hypotonic swelling is followed by a regulatory volume decrease (RVD) phase. This was confirmed by both electron microscopy and by cellular water determinations. The rate of regulatory shrinking was proportional to the degree of hypotonicity in the 0.5-0.9 X isotonic range. Cell viability was only marginally affected in this range. The content of cellular K+ decreased during RVD, while Na+ content remained unchanged. Similarly, the efflux of 86Rb (used as a K+ analog) increased upon dilution, whereas 22Na efflux was not altered. 86Rb uptake was enhanced by hypotonic stress and both ouabain-sensitive and -insensitive components were affected. A ouabain-sensitive stimulation was also seen in Na+- free media. Ouabain partially inhibited RVD only if added to the cells hours before hypotonic challenge. A normal shrinking response was observed in K+-free media, and also in Na+-free media when Li+, choline+, or Tris+ were the substitutes. In high K+ or RB+ hypotonic media shrinking was absent and a second swelling phase was observed. Cs+ displayed an intermediate behavior, with shrinking observed at lower dilutions and secondary swelling at higher ones. The direction and magnitude of the response also changed when the external K+ concentration was varied and, with 50 mM K+, no regulatory volume change occurred following hypotonic stress. These findings suggest that RVD occurs largely by a passive loss of cellular K+, resulting from a selective increase in permeability to this ion. In addition, the (Na-K) pump appears to be activated upon cell swelling by a mechanism other than Na+ entry into the cell, but this activation is not essential for RVD.

Carbamylcholine modulation of E-rosette formation. Effect of plasmapheresis in myasthenia gravis

Myasthenia gravis may result from a reduction of available acetylcholine receptors at the neuromuscular junction, likely secondary to the presence of anti-acetylcholine receptor antibodies. Since T lymphocytes appear to carry a similar nicotinic acetylcholine receptor, we investigated the capacity of T cells from patients with myasthenia gravis to bind sheep erythrocytes. In addition we determined the effect of carbachol, a cholinergic agonist, on E-rosette formation, and the role of myasthenic serum in modulating these responses. Two groups of patients were identified; one with normal numbers of E-rosettes forming cells (E-RFC) and the other with significantly reduced numbers. The majority of patients with myasthenia had a reduced number of carbachol-sensitive T cells. Incubation of their serum (or the IgG fraction) with normal T cells led to a reduction in numbers of E-RFC, particularly of the carbachol-sensitive subset. These effects were blocked by d-tubocurarine and not by atropine. Following plasmapheresis, normal numbers of E-RFC were detected in the patients and the serum inhibitory activity was no longer detected. The data suggest that in parallel to the achievement of some degree of clinical improvement, plasmapheresis may restore some aspects of lymphocyte function.

Hypothesis: the role of interleukins in lymphopoiesis - important in autoimmune disease?

The development of multiorgan autoimmune disease is considered in a framework of human lymphocyte ontogeny and immune regulation. A hypothesis is presented that accommodates many typical features of the clinical course and laboratory abnormalities of autoimmune disease by assuming the presence of underlying defects in lymphocyte differentiation. Altered production of and response to poietin-like mediators such as interleukins may be responsible for many of these abnormalities and represent prime candidates for further research into the pathophysiology of autoimmune diseases.