Selective triggering of human T and B lymphocytes in vitro by polyclonal mitogens

Phytohemagglutinin-induced proliferation and cytolytic activity in T3+ but not in T3- cloned T lymphocytes requires the involvement of the T3 antigen for signal transmission

Proliferation and the cloning efficiency of T3+ but not T3- T cells are increased by the addition of lectins (phytohemagglutinin; PHA) to the culture medium. In contrast to that of T3+ cloned cell lines, the cytolytic activity of T3- clones is not enhanced by PHA, as we report here. We have investigated the effects of anti-T3 monoclonal antibody (MAb) and PHA on the proliferative capacity and cytolytic activity of various T3+ and T3- clones and cells to determine the possible involvement of the T3 receptor in these processes. We found that, in addition to inhibition of allospecific cytotoxicity, anti-T3 MAb can induce and/or enhance nonspecific cytolytic activity against particular target cells in cloned allospecific cytotoxic T cells (CTL) following preincubation of the effector cells with PHA or anti-T3. This enhancement of cytolytic activity is seen in T3+ but not T3- activated killer (AK) clones or fresh T3- natural killer (NK) cells and depends on the concentrations of anti-T3 MAb or PHA used. We conclude that the T3-Ti antigen-receptor complex is involved in the transmission of the activation signals by anti-T3 and PHA.

Mitogenic responses of baboon (Papio cynocephalus) peripheral blood mononuclear cells. A possible role for monocytes

Removal of carbonyl iron-adherent/phagocytic cells from baboon peripheral blood mononuclear cells generally resulted in a depressed blastogenic response to both pokeweed mitogen and concanavalin A. In the majority of cases, no alteration in dose requirement nor shift in kinetics was apparent. Staining for peroxidase activity indicated a reduced proportion of monocytes in the population of cells treated with iron. Therefore, the results of this study strongly suggest a potentiating role for monocytes in lectin stimulation of baboon lymphocytes.

Animal studies of toxic shock syndrome

Toxic shock syndrome (TSS) was first described in 1978 and since that year over 2990 cases have been reported to the Communicable Disease Center. The estimated case-fatality rate is 5.6%. The disease is characterized by fever, hypotension, rash, desquamation, and involvement of at least three other organ systems. Approximately 85% of the cases are menstrually related and tampon use has been identified as a risk factor. The remaining 15% of the cases occur in both sexes and are not specifically related to age or geographic location. In all cases where sought there is evidence for infection by Staphylococcus aureus. Nearly all S. aureus isolates are phage type 52/29 and elaborate a unique exotoxin (toxic shock toxin). This review explores both the successful and unsuccessful attempts to induce toxic shock or a TSS-like syndrome in animals other than man. The review identifies the baboon as an animal model of TSS and discusses the clinical and pathologic sequellae, in this species, after exposure to purified toxic shock toxin.

Proliferative synovitis in rabbit knee joints induced by antigen and preformed immune complexes

Knee joints of non-immunized rabbits were repeatedly injected with bovine serum albumin (BSA) and preformed BSA-anti-BSA immune complexes which had differing precipitation profiles and abilities to activate complement. Ten days after the last of six injections the antibody and lymphoproliferative responses to BSA were analysed and correlated to the degree of arthritis. Joint swelling, increased numbers of joint fluid leukocytes and morphological changes typical of proliferative synovitis were found only in those rabbits injected with a large dose of antigen or with immune complexes prepared in antigen excess of poor precipitation and complement-activating properties in vitro. The degree of arthritis correlated with the development of humoral and lymphoproliferative immune responses to BSA.

Inhibition of lymphocyte proliferation by free fatty acids. I. Differential effects on mouse B and T lymphocytes

Saturated and unsaturated long-chain fatty acids were compared for their effects on mitogen-induced DNA synthesis in mouse B and T lymphocytes. At high concentrations (100-120 microM) all of the fatty acids tested were inhibitory to some extent, while at lower concentrations (20-60 microM) only the saturated fatty acids suppressed DNA synthesis. The inhibitory effects of the saturated acids could be reversed by the simultaneous addition of either a cis- or a trans-monounsaturated or a cis,cis-diunsaturated fatty acid. Compared to T cells stimulated with either phytohaemagglutinin or concanavalin A, B cells stimulated with either lipopolysaccharide or 8-bromoguanosine were considerably less susceptible to the inhibitory effects of the saturated fatty acids. These results demonstrate that free fatty acids may be useful tools for delineating the metabolic events involved in B cell and T cell activation.

Human colostral cells. II. Response to mitogens

The ability of colostral lymphocytes to respond to pokeweed mitogen, phytohemagglutinin, or Epstein-Barr virus was examined. None of these mitogens induced colostral cells to differentiate into immunoglobulin-containing cells, either in the absence or in the presence of mitomycin C-treated mononuclear cells or T-cell-enriched populations from peripheral blood. Cocultivation of mononuclear cells from the peripheral blood of normal adults with mitomycin C-treated colostral cells resulted in a marked suppression of the generation of immunoglobulin-containing cells in response to pokeweed mitogen. The inhibitory effect was seen in peripheral blood mononuclear cell:colostral cell ratios of 1:1, 5:1, and 10:1. However, colostral cells had little effect on the ability of peripheral blood lymphocytes to proliferate in response to phytohemagglutinin or to allogeneic stimulation.

A flow cytometric technique for quantitation of B-cell activation

A flow cytometric method for enumeration of intracytoplasmic antibody-containing cells was developed. Flow cytometry was found to yield results comparable to traditional fluorescence microscopy in cells stimulated to produce intracytoplasmic antibody by either pokeweed mitogen or Epstein-Barr virus. This technique offers several advantages over traditional fluorescence microscopy, including objective measurement of fluorescence intensity and rapid analysis of large numbers of cells.

Immunoenhancing effect of flavonoid compounds on lymphocyte proliferation and immunoglobulin synthesis

Flavonoid compounds are lipophilic agents which can interact with membrane lipids and may affect responsiveness of immune cells. We therefore studied whether cianidanol ((+)-catechin), the O-methyl-derivative (+)-3-methoxy-5,7,3',4'-tetrahydroxyflavan and palmitoyl-derivative (+)-3-palmitoyl-5,7,3',4'-tetrahydroxyflavan influence T and B cell functions. In addition, immunomodulatory property of ubiquinone 50 was also investigated. As controls were used cyclosporin A and inosine which are known to inhibit or enhance immune responses, respectively. The in vitro spontaneous, antigen and mitogen induced proliferation as well as immunoglobulin synthesis of peripheral blood mononuclear cells from healthy individuals was determined in the presence of different concentrations of the agents. All flavonoid compounds and ubiquinone 50 significantly increased (p less than 0.05 - less than 0.01) the spontaneous lymphocyte transformation but hardly affected antigen, alloantigen and mitogen induced proliferative response. Only cianidanol and O-methyl-derivative enhanced significantly (p less than 0.05 - less than 0.01) spontaneous, pokeweedmitogen and Staphylococcus aureus Cowan I induced immunoglobulin synthesis while the palmitoyl-derivative and ubiquinone 50 had only minor influence on B cell function. In contrast, Staphylococcus aureus induced immunoglobulin production was neither increased by inosine nor suppressed by cyclosporin A. These studies show that especially cianidanol and the O-methyl-derivative can exert an immunoenhancing effect on T and B cell functions.

Dihydrotestosterone regulation of thymocyte function in the rat mediation by serum factors

We have previously reported that reticuloepithelial cells of rat thymic tissue contain specific, high-affinity estrogen (E) and dihydrotestosterone (DHT) receptors which are not present in thymocytes, and that stimulation of the concanavalin A (Con A) sensitive thymocyte population is by means of a thymic serum substance depressed by estradiol. To ascertain if a serum substance modulated by DHT could also effect a thymocyte population, we incubated thymocytes in vitro for 3 days in the presence of the mitogens Con A or phytohaemagglutinin (PHA) + tissue culture media + 20% specific rat serum preparations and pulse labelled with tritiated thymidine. Rat serum samples were prepared from control, castrate, thymectomized (Tx) and castrate-Tx animals as well as from similar groups of animals treated in vitro for 3 days with physiological doses of DHT. It was found that there was a significant enhancement of thymocyte blastogenesis in cultures incubated with castrate rat serum + Con A or PHA vs control serum cultures (P less than 0.001). Direct replacement of DHT either to normal or castrate sera in vitro at physiological concentrations did not alter the level of thymocyte blastogenesis from normal or castrate controls. Sera prepared from castrate animals treated with DHT at physiological concentrations did not depress the blastogenic response, but sera from animals treated with testosterone were successful in depressing the blastogenic response to noncastrate levels. Sera prepared from Tx animals were stimulatory on thymocyte blastogenesis when PHA were utilized (P less than 0.02) and this stimulation was depressed in sera from animals treated in vivo with DHT. Sera prepared from Tx or castrate-Tx animals were not able to stimulate thymocyte blastogenesis when Con A was utilized but were stimulatory when prepared from castrate-Tx animals pretreated in vivo with DHT. It is hypothesized that Con A sensitive thymocytes are depressed by a thymic serum factor under the control of E and that both Con A and PHA sensitive thymocytes are depressed by a serum factor possibly of extrathymic origin that is under the control of DHT. A tentative hypothesis for the regulation of thymocytes by gonadal steroid hormones is presented.

Fatal infection in mice after injection of immunosuppressive serum fractions from surgical patients

Following surgical or accidental trauma many patients show suppression of cellular immunity. In this investigation sera from severely burned patients and patients undergoing aortic aneurysm repair were studied. Sera shown to suppress phytohaemagglutinin-induced blastogenesis of normal human lymphocytes were fractionated using ion exchange and G25 Sephadex chromatography. Suppressive activity was largely confined to a low molecular weight (LMW) fraction and was dose dependent. LMW fractions of normal sera had no significant suppressive activity. The purpose of this study was to test the causal relationship between immunosuppressive serum and decreased resistance to bacterial infection. Listeria monocytogenes infected mice were used as an in vivo model to test suppression of cellular immunity. Injection of LMW fractions of suppressive sera significantly increased mortality in these mice, but had no effect on non-infected mice. There was good correlation between the in vitro and in vivo effects of the suppressive fractions. These results suggest that a circulating factor in the serum of injured patients suppresses cellular immunity and may be responsible for impaired resistance to infection.

Isolation and characterization of human B lymphocyte enriched populations. I. Purification of B cells by immune rosette depletion

In the present study we describe a technique for the preparation of a highly purified B cell population from peripheral blood mononuclear cells (PBMC) by immune rosette depletion of non-B cells utilizing monoclonal antibodies directed at T cells, monocytes and null cells. The non-rosetted population contains greater than 90% B cells after a single rosetting step. The technique is simple, rapid and reproducible and results in minimal cell loss. In contrast, the E rosette negative (E-) fraction contains approximately 20% B cells whereas the surface immunoglobulin positive (sIg+ population obtained by Sephadex-anti-F(ab')2 column chromatography is comprised of approximately 60-80% B cells.

T-cell subsets in human lymphocytes maintained in IL-2 medium after PHA or mixed lymphocyte reaction activation

The culture of human T lymphocytes in interleukin-2 (IL-2) containing growth factor medium results in a significant shift in the T-lymphocytes subsets isolated from such cultures at weekly intervals. If normal peripheral blood mononuclear cells are stimulated with phytohemagglutinin (PHA) or in a mixed lymphocyte reaction (MLR), the resulting T lymphoblasts can be propagated in growth factor medium. Staining of the cultured cells with monoclonal antibodies was evaluated by indirect immunofluorescence on a laser-activated flow cytometer (Ortho Spectrum III). The antibodies used were: OKT3 (mature T lymphocytes), OKT4 (helper/inducer T lymphocytes), OKT8 (cytotoxic/suppressor T lymphocytes, OKT10 (immature and "activated" lymphocytes), OKT11a (cells which rosette with sheep erythrocytes), and OKIa-I (HLA-DR constant region). Both PHA and MLR activation resulted in initial preservation of the OKT4+ subset predominance over OKT8+ T lymphocytes noted on normal circulating blood lymphocytes. However, during culture in T-cell growth factor medium, there was a progressive increase in the percentage of OKT8+ cells, and a concomitant decrease in OKT4+ lymphoblasts. The increase in OKT8+ cells in the MLR-stimulated cultures was paralleled by an increase in specific cell-mediated cytotoxicity against the stimulating lymphocyte population. In addition to the shift in T-lymphocyte subset, there was virtual 100% staining with OKT3 and OKT11a, indicating the T-cell nature of the proliferating cells. OKT10 which was present on a small subset of fresh blood lymphocytes appeared rapidly in stimulated cultures, and was retained on virtually all lymphoblasts of either OKT4+ or OKT8+ subset. OKIa-1 cells increased slowly in PHA-stimulated cultures. HLA-DR+ T cells were detected earlier in MLR cultures. The activation of T lymphocytes results in a significant increase in the number of molecules of OKT11a bound per cell, in concert with the increased avidity of T lymphoblasts for sheep erythrocytes. The significant change in the phenotype and function of lymphoblasts isolated from long-term cultures demonstrates the importance of monitoring cultures, and the potential hazards in equating a cultured cell population with a freshly isolated one.

Chromosome replication in normal and transformed human lymphocytes

We analyzed the late-replication patterns of human B-lymphocyte chromosomes before and after transformation by Epstein-Barr virus. There were no statistically significant differences between normal cells and transformed cells derived from the same male individual; therefore, the order of termination of chromosome replication was unchanged by transformation. We also examined the replication patterns of T lymphocytes from the same donor and found no differences between normal B and T cells.

An improved technique for separating rosetted from non-rosetted lymphocytes

An improved technique for separating rosetted from non-rosetted lymphocytes is described. The major advantage of this new technique is the elimination of the need to mechanically resuspend the cell pellet resulting from the rosette formation step before using a density gradient to separate the rosetted from the non-rosetted cells. Instead the rosette containing cell pellet is directly overlayed with Percoll at a density of 1.078 g/ml and during a subsequent centrifugation the non-rosetted cells float to the surface of the Percoll while the rosetted cells remain in the cell pellet. The utility of this technique is illustrated by separating human T lymphocytes forming rosettes with neuraminidase treated sheep erythrocytes (En) from other mononuclear cells obtained by Ficoll-Hypaque separation of whole blood. Using several markers the resulting T cells were contaminated with less than 0.3% monocytes and 2% B cells. The non-T cell population contained less than 3% T cells. This method offers a rapid and easily reproducible means for obtaining highly purified cell populations.

In vitro analysis of lymphocytes: markers and functions

Current dermatologic literature is becoming replete with articles elucidating current concepts in the pathophysiology of lymphocytic diseases. Much of this knowledge emanates from the increasingly sophisticated and complex methods of identifying lymphocytes. No longer does it suffice to know that B lymphocytes or T lymphocytes are present, but rather the key information involves knowing what subsets of these cells are present and/or their functional status. The reader attempting to assimilate all this information is thus confronted with an overwhelming, as well as frequently changing, array of analytic methods. This paper is presented as a review of thinking, principles, and methods employed in research on lymphocytic disease.

Spontaneous reverse haemolytic plaque formation. II. The role of T cells and monocytes in regulating immunoglobulin secretion by human peripheral blood B cells

A sensitive reverse haemolytic plaque assay was used on freshly isolated blood cells from normal human subjects to show that T lymphocytes and monocytes were both necessary for immunoglobulin production by unstimulated B cells cultured only for the time necessary to form plaques. When lymphocyte preparations were fully depleted of T cells by E-rosette formation overnight on ice followed by Ficoll-Hypaque centrifugation, the number of plaque-forming cells was reduced by up to 94%; this reduction was reversed by the replacement of T cells, although excess T cells suppressed plaque formation. Moreover, when T-cell function was blocked by 10-1000 ng of two monoclonal anti-T-cell antibodies, OKT3 or UCHT1, this significantly reduced or abolished spontaneous IgG plaques, and higher concentrations of either OKT3 or UCHT1 reduced the numbers of IgA and IgM plaques formed by B cells. The role of monocytes in spontaneous plaque formation was investigated. The removal of plastic-adherent cells from mononuclear cell preparations did not consistently result in a reduction in the numbers of plaques, but complement-mediated lysis of monocytes with either of two monoclonal antibodies with specificity for monocytes, OKM1 and FMC17, reduced by 50% the number of IgG, IgA and IgM plaques. This effect was reversed by addition of as few as 1% plastic-adherent cells. Decreased plaque formation by B cells, resulting from either blocking of T-cell function with monoclonal antibody or complement-mediated lysis of monocytes, or both, was fully reversed by soluble factors present in cell-free conditioned medium from lectin-activated T cells. Thus spontaneous plaque formation by human peripheral blood B cells requires T cells and a small number of monocytes, and the major function of these cells is to help B cells by the production of soluble factors.

Survival and PHA-stimulation of gamma-irradiated human peripheral blood T lymphocyte subpopulations

Human peripheral blood T lymphocyte subpopulations were identified and isolated on the basis of their ability to bind IgG (T-G), IgM (T-M), or neither immunoglobulin class (T-null). Lymphocytes were exposed to 0, 0.5, 1.0, 2.5 or 5.0 Gy of 60Co gamma-rays either as a T-cell suspension or as separated T cell subsets. Survival curves, determined 5 days after irradiation, revealed that each subset has radiosensitive and radioresistant portions, and that the T-G cell is the most sensitive subset. Mitotic indices of 48-h cultures showed that the response of unirradiated T lymphocytes to PHA varied greatly among the subsets, the highest indices being obtained for the T-M and the lowest for the T-G cells. With the possible exception of the T-G cells, the subsets are relatively resistant to mitotic effects of gamma-rays. T-G cells suppress the PHA-induced mitotic response of the other T lymphocyte subsets, and this suppressor effect is radiosensitive, being abolished by 1.0 Gy. It is concluded that lymphocytes exposed to greater than or equal to 1 Gy of gamma-rays will have very few dividing B lymphocytes or T-G cells. This together with radiation-induced loss of T-G suppressor action means that the predominant lymphocyte types in mitosis after greater than or equal to 1 Gy are the radioresistant T-M and T-null cells.

The effect of suboptimal concentrations of mitogens on the immunosuppressive action of azathioprine and prednisolone on human lymphocytes in vitro

The interaction of two commonly used immunosuppressive agents, azathioprine (AZA) and prednisolone sodium succinate (PSS), with three mitogens, Concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) was studied. Using the endpoint of 50% inhibition of 3H-thymidine incorporation (ID50) as an indicator of cellular replication, the affect of suboptimal and optimal concentrations of mitogen on the immunosuppressive action of AZA or PSS on human lymphocyte replication in vitro was determined by isobolic analysis. The AZA ID50 for optimal concentrations of Con A (60 mcm/cc) was 242 +/- 21 ngm/cc (mean +/- SEM, n = 8), and at a suboptimal concentration of Con A (20 mcg/cc) it was 233 +/- 42, i.e., the AZA ID50 was independent of the concentration of Con A. This same independent interaction was found for PHA and PWM. However, at the optimal concentration of Con A (60 mcg/cc) the PSS ID50 of 523 +/- 55 ngm/cc was significantly higher (p less than 0.001) than the PSS ID at the suboptimal concentration of Con A (20 mcg/cc) which was 234 +/- 24 ngm/cc. A similar antagonistic interaction was found between PSS and either PHA or PWM. These findings emphasize the importance of accurately defining the testing parameters when assessing a drug's effect on lymphocyte proliferation. The data, along with other studies, support the hypothesis that drugs which directly interfere with DNA synthesis will not be affected by the strength of the signal for cellular replication, whereas those that modulate cellular replication are affected by the strength for lymphocyte replication.

Effect of Staphylococcus aureus Cowan i bacteria on the mitogenic response of human B-cell subsets

We have made a detailed investigation to determine which of the B-cell subsets could be stimulated by Staphylococcus aureus Cowan I bacterium (SpA CoI). B-cell subsets were separated from peripheral blood and tonsil lymphocytes by means of rosette formation with E, EAIgG, anti-immunoglobulin (Ig) conjugated OE (OE-Pro A) or by separation on a bovine serum albumin (BSA) discontinuous density gradient. The cells responding to SpA CoI included E receptor negative (E-), C3 receptor positive (C3R+), and surface Ig positive (SIg+) B-cell subsets. Among these B-cell subsets, FcR-n cells were more responsive than FcR+ cells. These B-cell subsets responded alone to SpA CoI and significantly proliferated, although, they failed to respond alone to pokeweed mitogen (PWM) and Protein A of S. aureus (Protein A). Among the SIg+ B-cell subsets stimulated with SpA CoI, IgM+ and IgG+ B cells showed much less response. Both Protein A receptor positive (Pro A . R+) and negative (Pro A . R-) cells responded well to SpA CoI. Fractionation of B cells on a BSA gradient revealed that comparatively small sized and denser B-cell subsets responded well to SpA CoI. From these criteria, it is suggested that B cells responding to SpA CoI are capable of stimulating not only mature B cells, but can also stimulate immature B cells.

Immunostimulating polysaccharide separated from hot water extract of Angelica acutiloba Kitagawa (Yamato tohki)

Separation of immunostimulating polysaccharide (ATP) from Angelica and its biological activities were investigated. AIP was separated as an acetone-insoluble and non-dialysable fraction from hot water extract obtained by heating the root of Angelica acutiloba in water at 95 degrees-98 degrees for 30 min. It is a water-soluble heteropolymer(s) consisting of uronic acid, hexose and peptide. The anti-tumour activity of AIP was observed in terms of prolongation of the survival period of mice bearing Ehrlich ascites cells. The uptake of tritiated thymidine into murine and human spleen cells could be stimulated by AIP in a dose-dependent manner. Murine B cells were activated polyclonally by AIP and differentiated to anti-body-forming cells even in the absence of either helper T cells or macrophages. The possibility that the biological activity of AIP might be due to contamination by bacterial lipopolysaccharides (LPS) or lipid A-associated protein (LAP) was ruled out for the following reasons: (i) polyclonal B-cell activation by AIP was shown in spleen cell cultures of C3H/HeJ mice, a low responder strain to LPS; (ii) the activity of AIP disappeared completely after a mild periodate oxidation whereas that of LPS containing LAP was not lost by similar treatment. In addition, the primary antibody response to sheep-erythrocytes was markedly augmented by an intraperitoneal injection of AIP. This result show that AIP is a potent adjuvant.

Functional alterations in non-T cells in rheumatic heart disease

The mediation of the T cell lymphoproliferative response to streptococcal blastogen A by non-T mononuclear cells was studied in patients with rheumatic heart disease (RHD) and control subjects. Non-T cells are essential for T cell response to blastogen A. Non-T cells from RHD patients were less effective in enabling the T lymphocyte response to blastogen A than control non-T cells though no consistent difference was observed in the response to phytohaemagglutinin. The results suggest that a functional alteration is present in the non-T cells from RHD patients which might be related to the pathogenesis of the disease.

T-cell regulation of pokeweed-mitogen-induced polyclonal immunoglobulin production in mice. I. Characterization of helper T cells

T-cell regulation of pokeweed mitogen (PWM)-induced polyclonal immunoglobulin (Ig) production was studied in mice. Under optimal stimulating conditions, about 1000 Ig-producing cells were generated per 3 x 10(5) spleen cells and macrophages were required to generate Ig-producing cells from B lymphocytes. The response of splenic B cells to PWM was partially dependent upon helper T cells, whereas the response to lymph node B cells was completely dependent upon T cells. Helper activity was attributed not only to Lyt 1+ 2- but also to Lyt 1+ 2+ T cells. Co-operation between T and B cells, in this system, was not restricted by H-2 barrier.

Transformation of chicken lymphocytes stimulated by concanavalin A: response parameters

The culture conditions for obtaining the maximum transformation of chicken lymphocytes stimulated by the mitogen Concanavalin A are described in this paper. Lymphocytes were cultured in round bottom microtiter tissue culture plates and the incorporation of 3H-methyl-thymidine (3H-TdR) into lymphocyte deoxyribonucleic acid was used to quantitatively evaluate transformation. Maximum incorporation of 3H-methyl-thymidine occurred when 2 x 10(6) lymphocytes and 4 micrograms of Concanavalin A were added to each culture. Deoxyribonucleic acid synthesis was greatest during the period of 18 to 36 hours after addition of mitogen. Differences between chicken and mammalian lymphocyte cultures are discussed.

Imbalances in T-cell subpopulations in myasthenia gravis

Distributions of peripheral blood lymphocyte subpopulations and T-cell subsets were studied in 38 patients with myasthenia gravis (MG) and 23 healthy controls. T cells were detected by rosette formation with sheep red blood cells and B cells with erythrocyte-antibody-complement (EAC) complexes. T mu cells were identified by rosette formation of T cells with Ox RBC-IgM complexes, and T gamma cells with Ox RBC-IgG complexes. The means of total lymphocyte count and active T cell percentage were marginally significantly lower in MG patients than in normal controls (0.05 less than P less than 0.1). The mean percentage of T mu cells was higher in MG patients than in controls (50.2 +/- 11.8% vs. 38.5 +/- 15.3%, P less than 0.01), whereas that of T gamma cells in the former was lower than that in the latter (20.4 +/- 7.1% vs. 27.6 +/- 6.2%, P less than 0.001). Thus, the loss of regulatory suppressor T cells and the increase of helper T cells in the patients are in favour of regarding MG as an autoimmune disease. The fact that the percentage of T gamma cells was significantly decreased in MG patients after autologus serum incubation, and that no such a phenomenon was seen in normal controls, may suggest a possible role of serum factors in the pathogenesis of MG.

Activation of human T and non-T lymphocytes by sepharose-bound concanavalin A and the differential effect of macrophages

The mitogenic effect of insoluble concanavalin A (Con A) bound to Sepharose beads on human peripheral blood mononuclear cells has been investigated. Sepharose-Con A, with a maximum activity at 100-400 micrograms/ml and an optimal incubation time of 3 or 4 days, stimulated the mononuclear cells with a high mitogenic response. Sepharose-Con A also stimulated the monocyte-depleted lymphocytes and their T- and non T-enriched fractions with a definite mitogenic response, although the levels of response were much lower than those of unpurified mononuclear cells. Addition of the adherent monocytes strongly augmented the Sepharose-Con A responses of monocyte-depleted lymphocytes and their T-enriched fractions, whereas it gave no effect on those of non-T-enriched fractions. Culture fluids of adherent monocytes also augmented the Sepharose-Con A responses of monocyte-depleted lymphocytes. These results indicate that, although insoluble Sepharose-Con A activates both human T and B cells, the response of T cells but not B cells may be dependent in part on the presence of monocytes or a monocyte-derived soluble factor(s). Thus, it is concluded that Sepharose-Con A may be a useful mitogen to elucidate the role of macrophages or their soluble factors in activation of human T and B cells.

Proliferation of PPD-stimulated lymphocytes measured by sister chromatoid differential staining

Lymphocyte proliferation in response to tuberculin-purified protein derivative (PPD) stimulation was measured by bromodeoxyuridine incorporation followed by sister chromatid differential staining PPD-stimulated lymphocytes responded identically to phytohaemagglutinin (PHA) stimulated lymphocytes in that there was a steady increase in the number of second- and third-division metaphases with a corresponding decrease in the number of first-division metaphases. However, the mitotic index was considerably less in the PPD-stimulated cultures. The response of PPD-stimulated lymphocytes was largely the result of repeated divisions of a small number of lymphocytes. Donors who had been treated for tuberculosis showed greater numbers of second- and third-division metaphases than donors who had received BCG vaccination. Third-division metaphases than donors who had received BCG vaccination. Third-division metaphases were also present in the PPD and PHA 48-hr cultures, indicating tha lymphocytes can both respond to stimulation and divide faster than was previously recognized.

Modification of lymphocyte DNA synthesis by alpha 1-antitrypsin

Purified human alpha 1-antitrypsin (alpha 1-AT) was shown to inhibit 3H-thymidine incorporation into mouse or human lymphocytes stimulated by various mitogens or by allogeneic cells. In the mouse, both B- and T-cell responses were affected. In the human, proliferative responses of peripheral blood lymphocytes, thymocytes and T-enriched tonsillar lymphocytes to phytohaemagglutinin were inhibited as well as that of tonsillar lymphocytes to Salmonella typhi-murium lipopolysaccharide. Spontaneous 3H-thymidine incorporation was moderately and inconstantly decreased, without evidence of altered cell viability. The inhibitory effect of alpha 1-AT appears to be related to its protease inhibitory capacity. These data bring further evidence for the role of proteolytic enzymes in the early events of lymphocyte activation, and support the hypothesis that serum inhibitors of proteases may contribute to the modulation of the immune response.

Fc receptors on human T lymphocytes: loss of Fc mu and expression of Fc gamma receptors by T cells stimulated in mixed lymphocyte reaction

The consequences of allogeneic stimulation on the expression of Fc mu or Fc gamma receptors were analysed in T-cell populations responding in mixed lymphocyte reaction (MLR). Unfractionated T-cell populations were cultured with a pool or irradiated allogeneic T-depleted cells. The responder E-rosetting cells progressively lost Fc mu and acquired Fc gamma receptors. The change of the original Fc receptor phenotype is not the consequence of a preferential proliferative response of TG versus TM cells but is likely due to a de novo expression of Fc gamma receptors by T cells lacking detectable Fc receptors (T-null) and also to the loss of Fc mu and expression of Fc gamma receptors by TM cells. These data suggest that, after MLR, responder T cells can modify their Fc receptor phenotype.

Stimulation of chronic lymphatic leukaemia cells by pokeweed mitogen after treatment with neuraminidase-galactose oxidase

CLL lymphocytes gave a low response upon stimulation with PHA or PWM in 3-day cultures. However, after treatment with neuraminidase-galactose oxidase (NGO), in the presence of PWM, CLL lymphocytes transformed into blasts and incorporated 3H-thymidine in 3-day cultures. This response of CLL lymphocytes was similar to that given by normal lymphocytes to PWM in 3-day cultures. The best stimulation of CLL lymphocytes was achieved when conditioned medium (CM) from normal T lymphocytes was present in PWM cultures. Purified B lymphocytes from CLL (T lymphocytes and monocytes removed) did not respond to PHA or PWM. However, after NGO treatment these cells were stimulated by PWM, but only in the presence of CM. PHA failed to stimulate NGO-treated CLL lymphocytes or purified B lymphocytes. This study shows that CLL lymphocytes, which usually fail to respond to mitogens, can be stimulated by PWM to proliferate after treatment with neuraminidase-galactose oxidase (NGO). This technique of B cell stimulation has been found useful in cytogenetic studies of B cell proliferative disorders.

Carbohydrate-labelled glycoproteins as markers of human lymphocyte subsets stimulated with mitogen and alloantigen

Human lymphocytes from thymus, spleen, and blood were stimulated by concanavalin A, phytohemagglutinin or pokeweed mitogen to incorporate radioactive thymidine and various carbohydrates. Peripheral-blood lymphocytes were also activated by alloantigen in a mixed lymphocyte reaction. Incorporation of thymidine and carbohydrates was parallel in stimulated cells. Carbohydrate-labelled cells were extracted with Triton X-100 buffer and the extracts subjected to sodium dodecylsulfate/polyacrylamide gel electrophoresis and subsequent autoradiography. From a comparison of the resulting glycoprotein patterns the following conclusions could be drawn. (a) The same population of thymocytes responds to all three mitogens. (b) Pokeweed-mitogen-stimulated blood lymphocytes are similar to this mitogen-responsive thymocyte population. (c) The glycoprotein pattern of pokeweed-mitogen-responsive spleen cells shows two characteristic glycoproteins, GP 50 and GP 78, and resembles that of murine B cells. (d) Whereas concanavalin A and phytohemagglutinin activate identical subpopulations of T cells in the spleen, this is not the case in the blood. (e) Concanavalin-A-activated and alloantigen-activated blood lymphocytes express a glycoprotein GP 185 which is not found on phytohemagglutinin-responsive cells. (f) The kinetic relationship during alloantigen stimulation in a mixed lymphocyte reaction between the appearance of glycoprotein GP 185 and subsequent maximal killing activity in an assay using release of 51Cr makes it likely that glycoprotein GP 185 is a marker for cytotoxic T lymphocytes.

Polyclonal activation of human peripheral blood B lymphocytes by formaldehyde-fixed Salmonella paratyphi B. I. Immunoglobulin production without DNA synthesis

A "new" polyclonal activator of human peripheral blood B cells, formaldehyde-fixed Salmonella paratyphi B, is described. This bacterium does not stimulate cell proliferation as measured by incorporation of tritiated thymidine but does stimulate a subpopulation of B cells to secrete large amounts of IgM, IgG, and IgA in 7-day cell cultures. The immunoglobulins (Ig) produced by cells responding to S. paratyphi B are not specific antibodies against the bacterial antigens. In comparison with other B cell activators (pokeweed mitogen, Staphylococcus aureus Cowan I, and lipopolysaccharide), S. paratyphi B stimulation produced greater amounts of IgM but less IgG than pokeweed mitogen (PWM) or S. aureus Cowan I; lipopolysaccharide failed to stimulate significant Ig production on day 7 in most cases. In addition, the response to S. paratyphi apparently did not require T cell collaboration. These results suggest that the B cell subpopulation(s) responding to S. paratyphi B may be more differentiated B cells than those responding to either PWM or S. aureus Cowan I. Peripheral blood mononuclear cells from five patients with common variable immunodeficiency without evidence of abnormal suppressor T cells or monocytes failed to respond to S. paratyphi B, whereas cells from two of the same patients responded well to S. aureus Cowan I and partially to PWM. Thus, S. paratyphi B appears to be superior to other B cell activators for studies of B cell function in normal and abnormal states.

Defective cellular immune response in vitro in common variable immunodeficiency

Mononuclear cells from 39 patients with hypogammaglobulinemia of the common variable type were analyzed for in vitro proliferative response to a panel of cell activators in order to examine the lymphocyte response to mitogens and to study the capacity to generate an immunologically specific secondary response. Patient lymphocyte response to phytohemagglutinin and concanavalin A was found to be significantly lower than that of controls studied in parallel (P less than 0.01), and low response did not correlate with T-lymphocyte number. Response to pokeweed mitogen was significantly lower than that of controls (P less than 0.01), but response to zinc, tested in a few patients, was normal. Strong depressions of patient lymphocyte proliferative responses to Candida albicans, Escherichia coli, and Staphylococcus aureus were observed (P less than 0.01); all of these microbial activators require intact B-cell function for maximum response. Repeated testing of individual patients indicated that poor lymphocyte response could be consistently observed. Examination of change in vitro lymphocyte response during clinical course and disease management showed that a consistent pattern of intrinsic lymphocyte functional deficiency could be demonstrated.

Polyclonal human T lymphocyte activation results in the secondary functional activation of the human B lymphocyte

The polyclonal T lymphocyte activators Con A and PHA were demonstrated to induce secretion of IgM and IgG as well as IgA antibodies in cultures of human peripheral blood lymphocytes. A similar response was seen in one-way mixed lymphocyte cultures and the kinetics, dose-response characteristics and optimal culture conditions are presented. The presence of functional T lymphocytes is a prerequisite for in vitro B lymphocyte activation in response to T lymphocyte mitogens. A narrow dose-response profile is a characteristic for both Con A and PHA and polyclonal B cell activation occurred at what have been previously regarded as suboptimal concentrations of these agents. The use of higher doses of these activators failed to generate immunoglobulin-secreting cells despite the presence of early and optimal levels of DNA synthesis in the cultures.

Mitogenic activity of staphylococcal exfoliative toxin

Exfoliative toxin from Staphylococcus aureus was mitogenic for murine spleen cells. It was primarily active on T lymphocytes but also significantly stimulated B cells from the spleens of nude mice. The mitogenicity was not affected by simple sugar or alpha-methylpyranosides. N-acetylglucosamine and N-acetylgalactosamine inhibited its effect. Exfoliatin was as powerful a mitogen as the enterotoxins of S. aureus. Some significant differences between the mitogenic activity of the two toxins were demonstrated.

Enhancement of lymphocyte response to PHA by lysosomal enzymes from polymorphonuclear leukocytes of RA joint fluid. I. Biological effect on T lymphocyte function

The effect of polymorphonuclear leukocyte (PMN) granule lysates obtained from joint fluid of RA on the in vitro DNA synthesis of PHA-stimulated autologous lymphocytes from joint fluid was studied. Lymphocytes were cultured for 3 days with or without PMN lysates in 2 ml of RPMI-1640 supplemented with 10% heat-inactivated fetal calf serum (FCS). The lymphocytes were stimulated with phytohemagglutinin (PHA-M). The DNA synthesis was measured by counting the [3H]thymidine incorporation. Lymphocytes from RA joint fluid stimulated with PHA-M showed 19,466+/-987 cpm (mean+/-SE) per 10(6) cells in the absence of PMN lysates. Upon addition PMN lysates to the PHA-stimulated lymphocytes, the maximum in vitro DNA synthesis increased to 44,877+/-1338 cpm. The enhancing effect of PMN lysates was abolished by plasma inhibitors or by passage through a column of protease inhibitor (Trasylol). It was concluded, therefore, that the enhancing effect of PMN lysates on PHA-stimulated lymphocytes may be associated with lysosomal proteases. Based on experiments using separated T and B lymphocytes, the enhancing effect of PMN lysates was considered to result from the activation of T lymphocytes. The results obtained in the present study suggest an important role for lysosomal proteases in the perpetuation of rheumatoid synovitis.

Suppression of polyclonal immunoglobulin biosynthesis by a soluble factor: T-cell dependent and T-cell independent mitogens

When normal human spleen cells are pulsed with concanavalin A (Con A), a portion become suppressor cells which in co-culture can inhibit immunoglobulin synthesis by other normal spleen cells stimulated by pokeweed mitogen (PWM). One mechanism whereby these Con-A activated spleen cells suppress Ig synthesis appears to be by the secretion of a soluble suppressor factor(s) since supernatants of Con-A stimulated splenocytes also suppress the polyclonal synthesis of immunoglobulin by human spleen cells. In this study, we report that supernatants of Con-A activated spleen cells suppress the in vitro synthesis of IgG, IgM and IgA by human spleen cells cultured with PWM. Our results indicate that the soluble suppressor factor(s) blocks an early stage in the differentiation of B lymphocytes into plasma cells without affecting the synthesis and secretion of immunoglobulin by more mature lymphocytes which appear to be irreversibly committed toward the pathway of synthesizing immunoglobulin. In addition, we studied the ability of normal human spleen cells to synthesize polyclonal immunoglobulin when cultured with either the T-cell dependent PWM or T-cell independent mitogens lipopolysaccharide (LPS) and Nocardia. Our results demonstrate that normal human splenic mononuclear cells cultured with either Nocardia, LPS or PWM are significantly stimulated to synthesize polyclonal IgG, IgM and IgA. Furthermore, supernatants of Con-A activated human spleen cells suppressed the polyclonal synthesis of these three antibody classes by human spleen cells responding to either T-cell dependent or independent mitogens.