Removal Of Phagocytic Cells Research Articles

Aggregated immunoglobulin protects immune T cells from suppression: dependence on isotype, Fc portion, and macrophage FcgammaR.

We determined the regulatory properties of heat-aggregated immunoglobulins (HA-Ig) that possess many activities of immune complexes (IC), such as binding and activation of cells via immunoglobulin Fc gamma receptors (FcgammaR). HA-Ig protected contact sensitivity (CS) effector T cells from antigen-specific immunosuppression, while monomeric IgG were inactive. This anti-suppressive activity of HA-Ig was antigen non-specific, and depended on the species from which Ig was derived, i.e. mouse and rat HA-Ig were protective in mice, and of other species were inactive. The protecting activity of HA-Ig was confined to IgG2a and IgG3, and to a lesser degree to IgG1 isotypes, and resided in the Fc domain. Removal of phagocytic cells from the CS-immune target cells, or blocking with anti-FcgammaR mAb, abolished HA-Ig protection of CS-effector T cells from suppression. We suggest that HA-Ig multimers acted via Fc domains, in one of two ways: by binding to FcgammaR of macrophages to produce positive-acting cytokines, or by blocking FcgammaR on macrophages, to compete with suppressive factors that can also bind to FcgammaR. If HA-Ig protection of T cells is generalized, it is likely that IC in vivo may non-specifically overcome suppression of responses to antigen that normally are under the control of T suppressive cells, and thus may contribute to the development of autoimmunity.

IgM-mediated opsonization and cytotoxicity in the shark.

Two types of cytotoxic reactions have been observed using cells from the nurse shark: spontaneous cytotoxicity mediated by cells of the macrophage lineage and antibody-dependent killing carried out by a different effector cell population. Previous data showed that removal of phagocytic cells using iron particles abolished macrophage-mediated killing, but not antibody-dependent reactions. The current study used single cell assays and showed that the effector of antibody-driven reactions was the neutrophil. Surprisingly, the mechanism of killing was shown to be phagocytosis mediated by both 7S and 19S immunoglobulin M (IgM). Reactions proceeded with as little as 0.01 microg of purified 19S or 7S IgM and were complete within 4-6 h. In contrast, purified immunoglobulin did not adsorb to macrophages and had no effect on target cell binding or cytotoxicity. Pretreatment of cells with cytochalasin D abolished the phagocytic reaction, but not spontaneous cytotoxicity. These data show that antibody-mediated killing results from opsonization and phagocytosis; the mechanism of macrophage killing is currently unknown. In addition, these data show that the shark neutrophil, not the macrophage lineage, carries a receptor for Fc mu.

Granulocyte-macrophage colony-stimulating factor overrides the immunosuppressive function of corticosteroids on rat pulmonary dendritic cells.

Pulmonary dendritic cells (DC) are present in extremely small numbers, but they are the most potent antigen-presenting cells in the lungs. Pure populations of DC can be isolated from the lung following collagen digestion, Percoll gradient centrifugation, removal of phagocytic cells and flow cytometric sorting for cells which exhibit high levels of surface major histocompatibility complex (MHC) class II molecules. Exogenous GM-CSF enhances this immunostimulatory capacity of the pulmonary DC. Soluble factors produced by type II airway epithelial cells and interstitial macrophages also enhance the immunostimulating capacity of pulmonary DC while alveolar macrophages suppress it. Thus, the function of DC may be regulated by locally produced cytokines. Corticosteroids are widely used as immunosuppressive agents in pharmacotherapy. While these agents are known to inhibit T cell proliferation and macrophage activation, their effects on DC are not known. We found that dexamethasone (Dex) pretreatment resulted in about a 50% reduction in the immunostimulatory capacity of rat pulmonary DC. This was associated with downregulation of MHC class II (Ia) expression. Dex-induced suppression of DC function could be restored with GM-CSF. We conclude that corticosteroids downregulate antigen-presenting capacity by direct suppression of pulmonary DC. This immunosuppressive effect of corticosteroids on DC may, however, be abrogated by exogenous GM-CSF. Corticosteroids and GM-CSF are therapeutic agents with potent direct immunomodulating effects on DC.

Characterization of murine lung dendritic cells: similarities to Langerhans cells and thymic dendritic cells.

Dendritic cells (DC) are potent accessory cells (AC) for the initiation of primary immune responses. Although murine lymphoid DC and Langerhans cells have been extensively characterized, DC from murine lung have been incompletely described. We isolated cells from enzyme-digested murine lungs and bronchoalveolar lavages that were potent stimulators of a primary mixed lymphocyte response (MLR). The AC had a low buoyant density, were loosely adherent and nonphagocytic. AC function was unaffected by depletion of cells expressing the splenic DC marker, 33D1. In addition, antibody and complement depletion of cells bearing the macrophage marker F4/80, or removal of phagocytic cells with silica also failed to decrease AC activity. In contrast, AC function was decreased by depletion of cells expressing the markers J11d and the low affinity interleukin 2 receptor (IL-2R), both present on thymic and skin DC. AC function was approximately equal in FcR+ and FcR- subpopulations, indicating there was heterogeneity within the AC population. Consistent with the functional data, a combined two-color immunofluorescence and latex bead uptake technique revealed that lung cells high in AC activity were enriched in brightly Ia+ dendritic-shaped cells that (a) were nonphagocytic, (b) lacked specific T and B lymphocyte markers and the macrophage marker F4/80, but (c) frequently expressed C3biR, low affinity IL-2R, FcRII, and the markers NLDC-145 and J11d. Taken together, the functional and phenotypic data suggest the lung cells that stimulate resting T cells in an MLR and that might be important in local pulmonary immune responses are DC that bear functional and phenotypic similarity to other tissues DC, such as Langerhans cells and thymic DC.

Effect of human blood mononuclear cell populations in antibody dependent cellular cytotoxicity (ADCC) using two murine (CO17-1A and Br55-2) and one chimeric (17-1A) monoclonal antibodies against a human colorectal carcinoma cell line (SW948).

Peripheral blood mononuclear cells (PBMC) from healthy individuals were studied for their lytic capability in ADCC using SW948 (a human colorectal carcinoma cell line) as target cells. Three monoclonal antibodies (MAbs) were used: two mouse MAbs (IgG2A) against the antigenic structures CO17-1A and BR55-2 respectively and one chimeric MAb 17-1A (IgG1) (mouse-human). Three kinds of effector cells were prepared. PBMC were purified on a Ficoll-Isopaque gradient (FIP cells) (a mixture of lymphocytes and monocytes). To obtain pure monocytes (greater than 90%), PBMC were centrifuged on a Nycodenz gradient (Nycodenz cells). Highly purified lymphocytes (greater than 98%) were obtained by treatment of FIP cells with iron powder and removal of phagocytic cells (PBL cells). Monocytes had the highest lytic capability. FIP cells were less effective than monocytes. PBL cells had the poorest killing activity. In reconstitution experiments addition of increasing amount of monocytes to PBL resulted in an augmented cytotoxicity. The numbers of Leu-M3+ cells, Leu-M5+ cells (monocytes) and CD16+ cells correlated positively to cytotoxicity. Higher concentration of MAb 17-1A was required to reach the same level of cytotoxicity using FIP cells as effector cells as compared to monocytes. MAb BR55-2 induced the same cytotoxic activity as MAb 17-1A. Combination of these two MAbs did not increase the lytic capability. Chimeric MAb 17-1A mediated ADCC in a dose-dependent fashion. The chimeric MAb was consistently more effective than the mouse MAb.

Role of the lymphatics in aiding regression of hypokalemic lesions in rat cardiac muscle: Steven Tepper and Wolfgang Mergner. Department of Pathology, School of Medicine, UMAB.

This study describes the role of lymphatics in the removal of macrophages from inflammatory lesions in the heart of hypokalemic rats and rats recovering from hypokalemia. The inflammatory lesions are characterized by focal cardiomyocyte necrosis, edema, and mononuclear infiltrate. The vascular and lymphatic capillaries are maintained along with the basement membrane of the necrotic cardiomyocyte. Through prior investigation, it was revealed that refeeding potassium led to a rapid reduction in lesion area. The purpose of the current investigation was to establish the role of the lymphatics as a means of reducing the lesion area by removal of the cellular infiltrate and edema. Using a limited potassium diet, hypokalemic rats were sacrificed via perfusion fixation during the hypokalemic and the potassium re-supplementation periods. Heart tissue was examined by light and electron microscopy. During the hypokalemic period, phagocytic mononuclear cells were found engulfing necrotic cardiac muscle cells. With refeeding of potassium, these phagocytic cells appeared to be diminished in number, a reduction that coincided with a decrease in the lesion size. Lymphatic channels were dilated and full of mononuclear cells. These channels were differentiated from the vascular capillaries by standard morphological criteria. In conclusion, the lymphatics play an important role in the healing process by reducing the lesion size through the removal of phagocytic cells and the uptake of proteinaceous material.

Effects of the removal of adherent and phagocytic cells on the spleen cell lymphoproliferative response of tumor-bearing mice.

Cell-mediated immunity was investigated in two BALB/c mouse tumor systems using the lymphoblastogenesis test with phytohemagglutinin as the mitogen. This lymphoproliferative response was quantitated using the Stimulation Index (SI). There was little evidence for suppressor cell activity in cell mixing experiments in which spleen cells from #51 cell-injected mice were mixed with spleen cells from normal mice. Following macrophage removal by Sephadex G-10 columns and carbonyl iron ingestion, there were no significant changes in the SI values for spleen cells from the #51 cell-injected mice. In contrast, spleen cells from mice injected with H238 cells, a herpes virus-transformed cell line, had a significantly lower SI value than that of normal mice. Suppressor cell activity was demonstrated in cell mixing experiments in which spleen cells from H238 cell-injected mice were mixed with normal spleen cells. Removal of adherent cells from spleen cells from H238 cell-injected mice by Sephadex G-10 columns restored the SI value to that of normal mice. An increased SI value was also seen after removal of phagocytic cells by carbonyl iron. These results suggested that cells with the functional properties of macrophages played an important part in the immunosuppression observed in the H238 tumor system. Comparison of the two macrophage depletion methods suggested that another cell population was also involved in the suppressive effect. Results of immunofluorescent techniques with anti-Lyt-1 and anti-Lyt-2 monoclonal antibodies show these cells to be Ly 1-, Ly 2,3+ phenotypes of T-lymphocytes.

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The antibody-dependent lytic activity of Corynebacterium parvum-induced peritoneal exudate cells was examined in vitro by utilizing AD755a tumor targets and a homologous anti-AD755a hyperimmune serum. Maximum antibody-dependent cell-mediated cytolysis (ADCC) of tumor targets was achieved within 4 hours of incubation. ADCC activity was found primarily in the plastic nonadherent cell population and was greatly enriched following removal of phagocytic cells by carbonyl iron. Phenotypically, the cells active in short-term ADCC were Qa-5+, ASGM-1+, Thy 1.2+, and NK 1.1+ and were unaffected by treatment with Lyt 1.2, Lyt 2.2, MAC-1, or I-Ab antibodies plus complement. Cells active in antibody-independent lysis of AD755a targets were phenotypically identical to antibody-dependent effectors. Although indicative of a natural killer (NK) cell phenotype, C. parvum-induced effectors differed from "spontaneous" splenic NK cells in their relative sensitivity to anti-Thy 1.2 as well as to anti-NK 1.1 treatment. Unlike the IgG2a-dependent lysis of AD755a-derived cells by inflammatory macrophages, all IgG isotypes of antiAD755a serum were equally effective in ADCC mediated by C. parvum NK cells. Finally, treatment of C. parvum-inoculated animals with anti-ASGM-1 serum eliminated in vitro NK activity and abrogated the in vivo therapeutic effects of hyperimmune serum. These findings, together with other correlations detailed herein, strongly suggested that C. parvum-activated NK cells appeared to represent a unique subset of NK cells that can serve as potent effectors in the antibody-dependent killing of AD755a tumor cells.

IMMUNOREGULATION IN AN ISOLATED 12-YEAR-OLD BOY WITH CONGENITAL SEVERE COMBINED IMMUNODEFICIENCY

We report the evaluation of in vitro immunoregulation in a 12-year-old untreated boy with severe combined immunodeficiency (SCID). Severely hypogammaglobulinemic, the patient was incapable of a specific antibody response to either natural substances or administered antigens. Ficoll-Hypaque-isolated peripheral blood mononuclear cells (MNL) from the patient failed to respond to pokeweed mitogen (PWM) with the normal increment in immunoglobulin-secreting cells (Ig-SC), as measured by a reverse hemolytic plaque assay. Since the patient was lymphopenic, his MNL were relatively enriched for monocytes (range = 51-81%). Removal of phagocytic cells or the addition of unrelated irradiated helper T lymphocytes resulted in enhanced, but still suboptimal response to PWM, suggesting some intrinsic defect in B lymphocyte function. Co-culture of patient MNL with normal MNL resulted in marked suppression (12% of predicted) of PWM-induced Ig-SC. Suppressor activity was unaffected by prior irradiation of patient MNL, but was substantially reversed (99% of predicted) by removal of his phagocytic cells; whereas the combination of the two procedures further reversed suppression (184% of predicted). The patient's MNL consistently demonstrated subnormal percentages of T3+ and T4+ cells and subnormal to low normal percentages of T8+ cells. These data suggest both an intrinsic defect in B lymphocyte function, and a relative excess of monocytes which could further inhibit Ig secretion by B lymphocytes. Natural killer cell function was severely depressed.

Stimulation of human and murine bone marrow cell colony formation by colony-stimulating factors obtained from the urine of mice bearing leukocytosis-inducing fibrosarcoma.

Dialyzed urine of mice bearing leukocytosis-inducing fibrosarcoma stimulated granulocyte colony formation in semisolid agar culture of human bone marrow cells. Removal of phagocytic cells prior to stimulation did not interfere with the formation of these colonies in the culture. On the other hand, macrophage colonies were predominantly produced when murine bone marrow cells were stimulated by the dialyzed mouse urine. The activity of colony-stimulating factor (CSF) in the urine of normal mice was less than 1/100 of that in the urine of tumor-bearing mice. DEAE-cellulose column chromatography separated the activity stimulating human granulocyte colony formation from that stimulating murine macrophage colony formation. Further purification showed that a sialoglycoprotein with an apparent molecular weight of 80,000 corresponded to the macrophage CSF, which was devoid of activity toward human cells. The molecular properties of the human-active granulocyte CSF could not be studied further, because it was quite unstable.

Abnormalities of in vitro immunoglobulin synthesis by peripheral blood lymphocytes from untreated patients with Hodgkin's disease.

The immunoglobulin-synthesizing activities of peripheral blood mononuclear cells from 57 untreated patients with Hodgkin's disease and 47 normal subjects were compared. Cumulative amounts of IgM and IgG synthesized and secreted by unstimulated and pokeweed mitogen-stimulated cells over a 7-d period were determined in a solid-phase radioimmunoassay. Synthesis of IgM in unstimulated cultures and of both IgM and IgG in cultures stimulated with pokeweed mitogen was markedly reduced in patients with Hodgkin's disease, whereas the mean level of the spontaneous IgG synthesis was enhanced. The degree and frequency of in vitro abnormalities were not influenced by disease stage or histology. Depression of pokeweed mitogen-induced immunoglobulin synthesis did not correlate with excessive number of monocytes and it was unaffected by removal of phagocytic cells or addition to the cultures of monocytes from normal individuals. On the other hand, monocytes isolated from blood of patients with Hodgkin's disease were even more effective than normal monocytes in supporting pokeweed mitogen-induced immunoglobulin synthesis by normal phagocyte-depleted mononuclear cells. Synthesis of both IgM and IgG induced by pokeweed mitogen remained subnormal after addition to patient B cell cultures of autologous irradiated T cells or allogeneic normal T lymphocytes. T cells from patients with Hodgkin's disease appeared at least as effective as normal T cells in helping pokeweed mitogen-induced immunoglobulin production by normal B cells. However, when normal T cells were co-cultured with B cells from patients with Hodgkin's disease, spontaneous IgG synthesis declined, whereas the addition of patient T cells to normal B cells resulted in an increase of spontaneous IgG synthesis. In patients showing depression of pokeweed mitogen-induced immunoglobulin synthesis the lymphoproliferative response and immunoglobulin synthesis stimulated by Staphylococcus aureus bacteria of the Cowan first strain, a T cell independent B cell mitogen, were also markedly reduced. These studies demonstrate impairment of immunoglobulin synthesis by cultured lymphocytes from untreated patients with Hodgkin's disease after stimulation with polyclonal B cell activators and suggest that the in vitro abnormalities may be, at least in part, the result of a preexisting in vivo activation of lymphocytes in Hodgkin's disease patients.

Characterization of the human peripheral blood effector cells mediating antibody-dependent cell-mediated cytotoxicity against respiratory syncytial virus

Peripheral blood lymphocytes were separated into several subpopulations and evaluated for their ability to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) against respiratory syncytial virus (RSV)-infected HeLa cells. Using erythrocyte rosetting methods, nylon wool filtration, and cytolysis with OKT-3 monoclonal antibody, two lymphocyte subpopulations were shown to mediate RSV-ADCC; non-T, non-B, and IgG-Fc receptor-bearing lymphocytes and E-rosetting cells with IgGFc receptors (Tγ cells). Removal of phagocytic cells did not alter ADCC activity. Monoclonal antibody to human NK and K cells, HNK-1, recognized these two lymphocyte effector subpopulations.

A partial characterization of suppressor cells in rat fetal liver cells

Rat fetal liver cells (FLC) obtained at 18–20 days gestation suppressed mixed lymphocyte reactions(MLR) of adult lymph node cells. The suppression was not strain specific: both syngeneic and allogeneic FLC were capable of suppressing the MLR. The same suppressor activity was observed with fetal spleen cells but not with fetal thymus cells. Removal of phagocytic cells from FLC failed to inhibit the suppressor activity. The suppressor cells were separated into two different types by BSA density gradient: one is radiosensitive, the other radioresistant. A stronger suppressor activity was observed in radiosensitive cells. The suppressor cells belonged to the fraction agglutinated with peanut agglutinin. The data suggest that the suppressor cells in rat FLC may be a proliferating blastoid-type cell rather than mature lymphocytes or mature macrophages.

Increased Sensitivity to Normal Adherent Suppressor Cells in Untreated Advanced Hodgkin’s Disease

AbstractMononuclear leukocytes isolated from the peripheral blood of 10 untreated patients with advanced stages of Hodgkin’s disease and 26 normal volunteers were stimulated with allogeneic cells from normal donors in a one-way mixed lymphocyte culture. When the patients’ cells were stimulated by an increased number of normal cells, the baseline mixed lymphocyte culture was suppressed 77.1% ± 4.1%. In contrast, when the normal responder cells were cultured with increased numbers of normal stimulator cells, mean suppression was only 46.6% ± 4.4% (p < 0.001). The removal of phagocytic cells from the high concentration of normal stimulators totally abolished the suppression observed with the patients’ cells, resulting in a mean increase in stimulation of 84% above that found in the baseline culture. The suppression could also be reversed by depletion of adherent cells from stimulator leukocytes. When adherent and nonadherent stimulator cells were recombined, significant suppression of proliferation was again observed. The increased suppression was not caused by the presence of autologous plasma in patients’ cultures, since similar results were obtained utilizing AB serum. The addition of indomethacin to the cultures only partially reversed the suppression observed with the patient’s cells. These studies demonstrate that mononuclear leukocytes from the peripheral blood of untreated patients with advanced stages of Hodgkin’s disease have increased sensitivity to a normal adherent suppressor cell system.

Increased sensitivity to normal adherent suppressor cells in untreated advanced Hodgkin's disease

Mononuclear leukocytes isolated from the peripheral blood of 10 untreated patients with advanced stages of Hodgkin's disease and 26 normal volunteers were stimulated with allogeneic cells from normal donors in a one-way mixed lymphocyte culture. When the patients' cells were stimulated by an increased number of normal cells, the baseline mixed lymphocyte culture was suppressed 77.1% +/- 4.1%. In contrast, when the normal responder cells were cultured with increased numbers of normal stimulator cells, mean suppression was only 46.6% +/- 4.4% (p less than 0.001), The removal of phagocytic cells from the high concentration of normal stimulators totally abolished the suppression observed with the patients' cells, resulting in a mean increase in stimulation of 84% above that found in the baseline culture. The suppression could also be reversed by depletion of adherent cells from stimulator leukocytes. When adherent and nonadherent stimulator cells were recombined, significant suppression of proliferation was again observed. The increased suppression was not caused by the presence of autologous plasma in patients' cultures, since similar results were obtained utilizing AB serum. The addition of indomethacin to the cultures only partially reversed the suppression observed with the patients' cells. These studies demonstrates that mononuclear leukocytes from the peripheral blood of untreated patients with advanced stages of Hodgkin's disease have increased sensitivity to a normal adherent suppressor cell system.

Human antigen-presenting cells: characterization of the cells in the T-lymphocytes proliferative response.

Human antigen-presenting cells (APC) which present the antigen to T lymphocytes resulting in a T-lymphocyte proliferative response were found among peripheral mononuclear cells (MNC), by employing purified protein derivative (PPD) as soluble antigen. To assess the adherence capacity of human antigen-presenting cells, MNC were separated by plastic Petri dishes or nylon wool columns. Plastic nonadherent cells were almost equivalent to unseparated cells in antigen-presenting ability. Plastic adherent cells, however, showed better antigen-presenting ability than unseparated cells. On the other hand, cells passed over nylon wool columns showed essentially no ability to present PPD to T lymphocytes. Removal of phagocytic cells by carbonyl iron resulted in about 50-70% reduction in antigen-presenting ability. Carrageenan, which is known to be toxic to macrophages, had no effect on APC. By using both rabbit anti-human Ia-like antiserum and alloantiserum specific for HLA-DR phenotype and complement, it was shown that APC possessed Ia-like antigens, whereas they did not bear surface immunoglobulins. These results indicate that the human APC is probably a cell in the monocyte-macrophage lineage. Allogeneic MNC were used as APC in order to determine whether any genetic restriction exists between MNC as APC and responding T lymphocytes. Optimal stimulation was shown to require identity of mixed leukocyte reaction (MLR)- activating determinants between APC and T lymphocytes. It is however, obscure whether an HLA-D region restriction exists in these combinations because PPD-pulsed allogeneic MNC lost their ability to elicit even MLR. It is possible that this failure to elicit MLR was caused by T lymphocytes among the MNC used as APC.

902 MONOCYTE SUPPRESSION OF IMMUNOGLOBULIN SECRETION IN A 9-YEAR-OLD BOY WITH SCID

We report the evaluation of in vitro immunoregulation in a 9-year-old untreated boy with SCID. Ficoll-Hypaque-isolated peripheral blood mononuclear cells (MNL) from the patient failed to respond to pokeweed mitogen (PWM) with the normal increment in immunoglobulin-secreting cells (Ig-SC), as measured by a reverse hemolytic plaque assay. Removal of phagocytic cells or the addition of unrelated irradiated helper cells resulted in enhanced, but still suboptimal response to PWM, suggesting some intrinsic defect in B-cell function. Co-culture of patient with normal MNL resulted in marked (88%) suppression of PWM-induced Ig-SC. Suppressor activity was unaffected by prior irradiation of patient MNL, but was substantially reversed (32% net enhancement) by removal of his phagocytic cells; whereas the combination of the two procedures further reversed suppression (52% net enhancement). Because the patient was lymphopenic, his MNL were relatively enriched for monocytes (range=40-80%). To determine whether the suppressor cell activity was due to functional or numerical excess of patient monocytes, co-cultures were performed using varying ratios of patient to normal MNL. Suppression was most marked in cultures containing >40% monocytes, suggesting that a numerical excess of patient monocytes could account for the observed suppression. These data suggest both an intrinsic defect in B-cell function, and a relative numerical excess of monocytes which could further inhibit Ig-secretion by B-cells.

Lymphocytes from multitransfused uremic patients have poor MLC reactivity.

Lymphocytes from uremic patients showed statistically significantly lower (P less than 0.01) MLC reactivity against pooled stimulator cells as compared with lymphocytes from age matched controls. A consistently low MLC reactivity was recorded in lymphocytes from patients who had received more than 20 units of blood and the lowest responses were seen with cells from patients with multispecific anti-HLA-antibodies. Removal of B cells and removal of phagocytic cells from the responder cells resulted in a significant (P less than 0.05) increase in MLC reactivity in the uremic but not in the control group. Both addition of enriched B cells to autologous enriched T cells and addition of adherent cells to non-adherent autologous cells caused a slight supression of MLC reactivity. PHA reactivity was lower (P less than 0.001) in lymphocytes from the multitransfused patients compared to cells from age matched controls. However, no difference in PHA responses were recorded between lymphocytes from uremic patients who had received less than 20 units of blood and controls.

Impaired immunoglobulin M synthesis by peripheral blood lymphocytes in systemic lupus erythematosus: A primary B-cell defect

Peripheral blood lymphocytes from 20 patients with systemic lupus erythematosus (SLE) were defective in their ability to secrete immunoglobulin M (IgM) in a pokeweed mitogen (PWM)-stimulated in vitro culture system. To characterize this abnormality, the mononuclear cells were separated into three functional subpopulations: (i) bone marrow-derived (B) cells which secrete immunoglobulin; (ii) a thymus-derived (T) lymphocyte fraction; and (iii) an irradiated T-cell fraction with predominant helper function. Coculture experiments with subsequent radioimmunoassay of the quantity of immunoglobulin secreted allowed comparisons of the immunoregulatory functions of the SLE-helper T, SLE suppressor T, and SLE B cells with functions of control lymphocyte fractions. The major defect defined was an inability of the SLE B cell to secrete normal amounts of IgM. This was not due to suppression by monocytes since the removal of phagocytic cells and the addition of separated monocytes to the cultures demonstrated generation of normal helper signals by SLE monocytes. Nor were inadequate numbers of IgM secreting B cells available since limiting dilution studies showed a normal precursor frequency of PWM-stimulatable, IgM secreting SLE B cells. SLE T cells showed a normal helper effect on the secretion of IgM by control B cells. Thus, these in vitro coculture studies designate a primary immunologic defect in SLE to the B cell and not in the suppressor or helper functions of the T cell.

A study of porcine lymphocyte populations II. Characterization of porcine lymphocyte populations

The percentage of E rosette forming cells amounted to 26% of the blood lymphocytes and 34% of the spleen cells in German Landrace pigs. 10% of the live lymphocytes in the peripheral blood and 22% of the spleen cells were EAC rosette forming cells. The number of E rosettes could be increased by treatment of sheep erythrocytes with neuraminidase. The number of lymphoid cells reacting with protein A in the peripheral blood and in the spleen of pigs correlated well with the number of EAC rosette forming cells. The mitogens phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) are potent stimulators of pig lymphoid cells. The mitogenic stimulation of pig lymphocytes could not be influenced significantly by the removal of phagocytic cells. By neuraminidase treatment the mitogen induced stimulation rate was decreased. For the mitogenic stimulation of porcine lymphoid cells in the presence of PHA, Con A and PWM T cells were required. Bacterial lipopolysaccharides (LPS) stimulated only B cells to a small degree.