The modulation of lymphocyte functions by molecules secreted by macrophages. I. Description and partial biochemical analysis

Alveolar macrophage subpopulations in patients with active pulmonary tuberculosis

Alveolar macrophages are a heterogeneous cell population. The heterogeneity of alveolar macrophages recovered by bronchoalveolar lavage (BAL) from 12 patients with active pulmonary tuberculosis (TB) and 10 normal subjects was studied using Percoll density fractionation. The numbers and subsets (on the basis of CD3, CD4, and CD8 monoclonal antibodies) of lymphocytes in BAL were measured by flow cytometry. Alveolar macrophages recovered from patients with TB were mainly in the lower-density fractions (< 1.030 and 1.030 to 1.040 g/ml), whereas alveolar macrophages from normal subjects were in the higher-density fractions (1.050 to 1.070 and > 1.070 g/ml). There were no significant differences in alveolar macrophages' repartition between smokers and nonsmokers in either patients with TB or normal subjects. The significant changes in the proportions of the lowest fraction and the higher fractions of alveolar macrophages in patients with TB were not altered after division of our patients into smoker and nonsmoker subgroups when compared with corresponding subgroups in normal subjects. The proportion of the alveolar macrophages in the lowest fraction was inversely related to the bacterial load of sputum and the disease extent on chest radiography in TB patients. The CD4/CD8 ratio was significantly higher in patients with TB. This study shows that alveolar macrophages from TB patients are heterogeneous with hypodense cells predominant probably by interaction with T lymphocytes. Changes in the proportions of alveolar macrophages within subpopulations may be of critical importance in determining the overall response of the lung to TB infection.

Macrophage-derived angiogenesis factors

A majority of angiogenic factors has been shown to be produced by macrophages. This review will give a concise description of their biochemical nature, their isolation from macrophages and their angiogenic activity. Among the factors with mitogenic effects on endothelial cells are basic fibroblast growth factor (bFGF), transforming growth factor-alpha (TGF-alpha) and very probably insulin-like growth factor-1 (IGF-1). Other secretory products such as angiotropin and human angiogenic factor (HAF) are nonmitogenic but promote angiogenesis by inducing migration of endothelial cells. Prostaglandins, platelet-derived growth factor (PDGF), granulocyte-macrophage- and granulocyte-colony stimulating factor (GM-CSF, G-CSF), interleukin 6 (IL-6) and angiotensin converting enzyme (ACE) have also been shown to be angiogenic, but their mode of action is still to be clearly defined. As the extracellular matrix appears to be involved in the control of angiogenesis, macrophage-derived factors that can alter this structure via degradation or via the clotting system will also be discussed. Tumor necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1) and transforming growth factor-beta (TGF-beta) have complex actions on endothelial cells, and can partially inhibit angiogenesis. Among the factors which solely inhibit neovascularization are the interferons. As it is not known whether all of these factors play a role in angiogenesis in vivo attempts to detect them in situ during the course of neovascularization will be described. Finally macrophages will be discussed as cells that may not be mandatory for each phase of the angiogenic process but whose angiogenic capabilities are comprehensive and unsurpassed by any other cell.

Early production of a chemotactic factor to T lymphocytes by peritoneal macrophages

Supernatant fluids (SNF) were obtained from peritoneal exudate adherent cells stimulated in vitro with sheep red blood cells (SRBC) or BCG, and SNF collected at 6 and 24 hr were able to induce the migratory responses of rat leukocytes from the spleen and peripheral blood. The production of these SNF was dependent on protein active synthesis upon in vitro antigenic stimulation. The chemotactic activity from 6-hr SNF was inhibited by using several proteolytic enzymes and temperatures. We found the macrophages to be the producer cell of this activity, while the T cells were the target cells. The chemotactic activity from 6-hr SNF was found not to be due to IL-1. Six-hour chemotactic activity has not been reported previously.

Effect of growth and differentiation stimuli on the development of antigen-responsive B cells in fetal liver

The development of the B cell immune repertoire was studied using an in vitro fetal organ culture system. In order to analyze the mechanism by which B cell precursors clonally expand and diversify, fetal lymphoid tissues were incubated in the presence of several factors known to influence B cell differentiation: IL-1, IL-2, WEHI-3 culture supernatant containing IL-3, and a factor from a cyclic neutropenia patient (CNF). By analyzing the effect of exogenous factors on the frequency of antigen-responsive B cells, the ability of the factor to either inhibit or enhance clonal expansion was determined. It was found that the addition of IL-1, WEHI-3 supernatant, or CNF increased the frequency of DNP-responsive B cells suggesting an enhancement of clonal expansion. IL-2, on the other hand, did not alter the frequency of antigen-responsive B cells. The effect of added factors on the kinetics of appearance of phosphorylcholine (PC)-responsive B cells, which are known to be acquired in ontogeny about 2 weeks later than DNP-responsive B cells, was also analyzed. The data indicate that CNF, unlike IL-1, IL-2, and WEHI-3 culture supernatant, results in an earlier appearance of PC-responsive B cells. These results suggest that soluble factors may play a role in the generation of the B cell repertoire.

Helper T-cell clones that recognize autologous insulin are stimulated in nonresponder mice by pork insulin

Murine antibody responses to various species of insulin are under major histocompatibility complex-linked Ir gene control. Beef insulin differs from pork insulin by only two amino acids in the A-chain loop, yet strain C57BL/10 (B10) mice produce insulin-specific antibodies after immunization with beef insulin and fail to produce antibody after stimulation with pork insulin. Nevertheless, pork insulin primes helper T cells in B10 mice that can be demonstrated if insulin-specific Lyt-1-, -2+ suppressor T cells are removed. Not only do the pork insulin-primed helper and suppressor T cells cross-react with autologous insulin, but also rat insulin (the amino acid sequence of which is identical to mouse insulin) elicits functionally identical helper and suppressor T cells. In this report, we demonstrate that in B10 mice the frequency of helper T cells stimulated by pork insulin is equivalent to that stimulated by beef insulin and that helper T-cell clones induced by beef and pork insulin are major histocompatibility complex-restricted T cells that proliferate, produce lymphokines, and provide helper activity after activation. These helper T-cell clones exhibit different antigenic fine specificities: beef insulin-induced clones respond to beef insulin but not pork or autologous insulin, whereas pork insulin-induced clones cross-react with all species of insulin tested, including rat insulin. In addition, the helper activity of cloned pork insulin-specific T cells is abrogated by pork insulin-primed suppressor T cells. These data support the hypotheses that Ir gene control of antibody responses to certain antigens involves mechanisms used for maintenance of self-tolerance.

Isolation of antigen-specific T cell clones from nonresponder mice

The mechanisms responsible for major histocompatibility complex (MHC)-linked unresponsiveness are still poorly understood. Here we examine the cellular events that follow when B10. A mice are immunized with cow insulin, an antigen to which they make no apparent immunologic response. Despite the fact that there is no detectable antibody or T cell proliferative response to cow insulin, we have been able to clone out responding T cells after priming and restimulating in vitro with this "nonimmunogenic" antigen. These cells are L3T4+, and co-recognize specific antigen and class II MHC gene products. The data demonstrate that "nonresponder" mice to cow insulin have both the capacity to present antigen and T cells capable of recognizing that antigen. The diversity within this population was investigated by analyzing various parameters of cellular activation. These include fine specificity of both antigen and MHC recognition, as well as recognition of allogeneic MHC and M1s determinants. In addition, the antigen-presenting cell requirements were studied. The results demonstrate that this population comprise a surprisingly heterogeneous group in terms of its repertoire of receptors.

The regulation of tissue eosinophilia. V. Induction of lymphocyte-derived eosinophil chemotactic inhibitory factor production by a macrophage product from complete Freund's adjuvant-treated guinea pigs

Splenic T lymphocytes of complete Freund's adjuvant (CFA)-treated guinea pigs spontaneously produce a lymphokine, eosinophil-directed chemotactic inhibitory factor (ECIF), which selectively inhibits the chemotactic response of the treated eosinophils to a certain chemotactic lymphokine for eosinophils. In the present paper, induction of spontaneous ECIF production was examined in CFA-treated guinea pigs. Although short-time (3-hr) cultured supernatants of CFA-treated spleen cells exhibited little or no ECIF activity, the supernatants could stimulate normal T lymphocytes to produce and release distinct ECIF activity. The factor with ECIF-releasing activity (ECIF-RF) was produced by splenic adherent cells of CFA-treated animals. ECIF-RF activity was absorbed only by T lymphocytes, suggesting that target cells of ECIF are T lymphocytes. ECIF-RF activity was eluted near cytochrome c (MW 12,500) on a Sephadex G-100 column. It was further found that ECIF-RF was sensitive to heating at 56 degrees C, to enzyme treatment with trypsin and neuraminidase, and to acid and alkaline condition. We thus concluded that ECIF-RF derived from adherent cells of CFA-treated animals may be involved in the suppression of cell-mediated tissue eosinophilia by stimulation of T lymphocytes to produce and release ECIF activity.

Bystander help in primary immune responses in vivo

We evaluated the requirement for hapten-carrier linkage in the primary, T cell-dependent antibody response in vivo. Mice immunized with mixtures containing nonimmunogenic and immunogenic proteins developed antibody that was specific for determinants present on the nonimmunogenic carrier. Therefore, hapten-carrier linkage was not necessary for the generation of primary antibody responses. The magnitude of the bystander response was a function of the immunogenicity of the coimmunogen and the quantity of determinant-specific B cells available for activation. Interestingly, the kinetics of the bystander response, in contrast to the cognate response, were not accelerated in the presence of primed Th cells. Adoptive recipients reconstituted with primed Th cells developed accelerated cognate but not bystander antibody response, as compared with unprimed recipients. This phenomenon may reflect a regulatory mechanism invoked to limit the potentially harmful effects of nonspecific help. It was observed that while animals are tolerant to immunization with mouse (self) hemoglobin, immunization with a mixture containing mouse hemoglobin plus fowl gamma globulin resulted in the production of hemoglobin-binding autoantibodies. Thus bystander help induced by coimmunization may serve as a model for the induction of autoantibodies during normal immune responses in vivo.

Investigations into the mechanism of immunosuppression caused by acute treatment with O,O,S-trimethyl phosphorothioate. II. Effect on the ability of murine macrophages to present antigen

Acute administration of 10 mg/kg O,O,S-trimethyl phosphorothioate (OOS-TMP) for 24 h has been shown to suppress the in vitro generation of cytotoxic T lymphocyte responses and antibody-secreting cells to sheep red blood cells and to increase interleukin-2 production. Macrophages were shown to be the splenic cell population most affected by OOS-TMP pretreatment. In this report, the ability of macrophages from OOS-TMP-treated animals to function in antigen presentation was shown to be significantly decreased. In addition, macrophages from treated animals had increased phagocytic capability and interleukin-l production. However, the percentage of Ia-positive macrophages present in splenic populations was decreased following OOS-TMP treatment. A decrease in antigen presenting ability and the number of Ia-positive macrophages may explain the reversible suppression in cytotoxic T lymphocytes and antibody responses reported previously.

Production of a lymphocyte proliferation potentiating factor by purified polymorphonuclear leucocytes from mice and rabbits

Highly pure polymorphonuclear leucocytes (PMN) were prepared from peritoneal exudate cells which were induced by an i.p. injection of casein into C3H mice and rabbits. The PMN were tested for the production of a lymphocyte proliferation potentiating factor with various stimulations in vitro. In both animal species, the purified PMN from the inflammatory site 3 hr after injection (3-hr PMN) produced the factor upon stimulation with kaolin, while the purified PMN from the lesion 24 hr after injection (24-hr PMN) did not. The 3-hr PMN produced the potentiating factor during a relatively earlier period after in vitro stimulation with kaolin. Protein synthesis inhibitors did not inhibit the factor production, suggesting the release of a preformed factor from 3-hr PMN. The effect of kaolin did not appear to be simply due to its cytotoxicity, because the release was dependent on the metabolism of 3-hr PMN and not parallel with 51Cr-release from the PMN. The factor produced by mouse PMN had an MW of about 15,000-25,000; it consisted of two isoelectrophoretically distinct factors, i.e. pI 9.4 and 5.4. The rabbit PMN factor was slightly smaller (MW ranging between 10,000 and 20,000) than the mouse PMN factor and was composed of three pI species, i.e. 7.2, 5.4, and 4.5.

Selection of the delayed hypersensitivity T effector and T suppressor cell response by antigen-presenting macrophages

The T effector lymphocytes of delayed type hypersensitivity reactions (TDH) are regulated by a complex T suppressor (Ts) cell circuit. Induction of TDH cells requires Ia+ adherent cells as antigen-presenting cells. Little is known about the antigen presentation of the induction of Ts cells. We describe an experimental model in which TDH and Ts cells are induced separately by different antigen-presenting macrophages grown from bone marrow stem cells. Bone marrow derived macrophages grown in L cell-conditioned medium for various periods and labeled with 2,4-dinitrobenzene sulfonic acid differ in their ability to induce TDH and Ts cells in vitro. The functional activity of the two T subpopulations was assessed in vivo by epicutaneous challenge or sensitization with 2,4-dinitrofluorobenzene of mice receiving the in vitro educated cells. Ear swelling or suppression of swelling was recorded. It could be shown that 5-7 day bone marrow-derived DNP-labeled macrophages preferentially induced Thy 1+ Lyt 1+ antigen-specific TDH cells; 7-10 day old antigen-presenting bone marrow-derived macrophages induced preferentially Thy 1+ Lyt 2+ antigen specific Ts cells. Characterization of various phenotypic markers revealed different surface antigen expression and functional differences such as MIF responsiveness or transglutaminase activity on the two macrophage populations. These data support the concept that activation of the Ts regulatory circuit may require antigen presentation by specialized antigen presenting cells, characterized by certain surface and functional markers and different from those inducing preferentially TDH cells.

Regulatory mechanisms in immune responses to heterologous insulins. II. Suppressor T cell activation associated with nonresponsiveness in H-2b mice

Murine antibody responses to insulins are controlled by MHC-linked Ir genes. Although mice of the H-2b haplotype do not make antibody in response to pork insulin, we demonstrate in this communication that immunization with pork insulin stimulates radioresistant, Lyt-1+2- helper T cells that are capable of stimulating secondary antibody responses to pork insulin in vitro, but that this activity is masked by radiosensitive, Lyt-1-2+, I-J+ suppressor T cells. The suppressor T cells, present after immunization with pork insulin but not beef insulin, suppress the secondary response to pork but not beef insulin. The amino acid sequences of pork and beef insulins differ only at the A-chain loop; thus, pork insulin-specific suppressor T cells appear to recognize the A-chain loop determinant of pork insulin. The amino acid sequences of mouse and pork insulin are identical in the A-chain loop, which suggests that these suppressor T cells may be self-reactive. If this interpretation is correct, these suppressor T cells could be involved in the maintenance of self-tolerance to insulin. Nevertheless, these data clearly demonstrate that genetically determined nonresponsiveness in H-2b mice is conferred by activation of dominant, insulin-specific suppressor T cells (Ts), rather than by a defect in the stimulation of insulin-specific helper T cells (Th).

Microsystem for in vitro primary and secondary immunization of channel catfish (Ictalurus punctatus) leukocytes with hapten-carrier conjugates

Methods are described for the in vitro generation and detection of antibody-secreting cells (PFC) from channel catfish. Hapten-specific PFC can readily be enumerated by an indirect plaque assay employing rabbit antiserum to catfish Ig and guinea pig complement. A modified Mishell-Dutton-type culture system was developed for effectively generating significant in vitro anti-hapten PFC responses with catfish leukocytes at 27 degrees C. The classical hapten-carrier effect and primary responses to both TI and TD antigens were demonstrable with catfish cells. Variables found to be important with catfish cells included the serum supplement, cell densities and, to a lesser extent, antigen form. Optimistically these methods will prove useful in attempts to delineate the functional roles of different lymphocyte subpopulations in fish.

Interleukin 1 secretion is not required for human macrophage support of T-cell proliferation

Interleukin 1 (IL-1) is a soluble factor secreted by stimulated monocytes (Mo) and animal macrophages (Mx). We have previously demonstrated that human Mo cultured in vitro for 1-6 days transform to Mx, and retain their ability to support concanavalin A (Con A)-driven T-cell proliferation. We have also shown that, paradoxically, these Mx do not secrete IL-1, when stimulated by endotoxin (LPS). In this study we examined two alternative hypotheses: T cells plus mitogen induce Mx IL-1 production, and human Mx deliver a second signal to T cells via a non-IL-1 mechanism. IL-1 was assayed in a mouse CD-1 thymocyte system without concanavalin A. Mo/Mx were cultured with T cells at low (2 X 10(4)/200 microliters) or high (1 X 10(5)/200 microliters) concentrations for 2 or 4 days, in the presence of Con A. Six hours prior to quantitation of proliferation, 50 microliters of supernatant was removed and assayed for IL-1. As expected both Mo and Mx enhanced T-cell proliferation eight- to tenfold. Mo secreted large amounts of IL-1; there was no demonstrable IL-1 activity present in supernatants from cultures containing either T cells and Mx, or Mx alone. Similar results were obtained by preincubating the cells (Mo, Mx, and T cells) with Con A for 12 hr and removing Con A prior to a 36-hr coculture. We examined the possibility that a small amount of IL-1 may be able to support Con A-stimulated T-cell proliferation and yet may not induce thymocyte proliferation. The highest dilutions of Mo supernatant (1:125) which supported T-cell proliferation also caused a fivefold increase in thymocyte proliferation. Supernatants from Mx failed to stimulate thymocyte proliferation or support Con A-driven T-cell proliferation. However, Mo and Mx lysates contain Il-1 activity. We conclude that human Mx support Con A-induced T-cell proliferation in the absence of IL-1 secretion. Mx may support T-cell proliferation by cell-bound IL-1 or by a non-IL-1 mechanism.

Evaluation of the proliferative response of lymphocytes by measurement of intracellular ATP

The measurement of intracellular ATP levels by luciferin-luciferase-induced bioluminescence was used for the evaluation of proliferative responses of human mononuclear cells to lectins. A linear relationship was observed between the number of cells and the amount of ATP in the samples, and high reproducibility was obtained. The ATP content of samples containing lectin-stimulated mononuclear cells increased with time, and a significant difference from unstimulated cells was obtained 48 h after initiation of the culture. Furthermore pretreatment with mitomycin C strikingly increased the ATP level of lectin-stimulated cells, but not that of unstimulated cells was obtained. These findings suggest that the proliferative response of mononuclear cells can be measured simply without the use of isotopes, and that earlier events occurring in stimulated cells may be analyzed by this simple method.

Regulatory mechanisms of the immune response to heterologous insulins. I. Development and regulation of plaque-forming cell responses in vitro

We, as well as many other investigators, have been studying the regulation of immune responses to insulin as a model system of H-2 linked immune response (Ir) gene control. Although antibody responses by mice to heterologous insulins are qualitatively controlled, antibodies that are generated to one species of heterologous insulin cross react extensively with other species. The exquisite control of responsiveness is regulated by T cells that appear to recognize differences in the amino acid sequences of the A-chain loop of insulin. Our previous studies of the mechanism(s) by which Ir genes regulate T cell activity to insulin have been confined to an adoptive transfer model because traditional cell culture techniques using normal or insulin-primed spleen cells have failed to generate insulin-specific plaque-forming cell responses in vitro. In this communication we demonstrate that more vigorous immunization protocols and the use of lymph node T cells as a source of helper T cells can circumvent this problem. More importantly, all of the major features of the regulation of responses to insulin that have been observed in vivo are reflected in this in vitro system. Thus, these experiments provide the essential foundation for future dissection of the mechanism of Ir gene control of responses to insulin.

Functional significance of the regulation of macrophage Ia expression

The relationship of Ia expression and antigen-presenting function by macrophages has been evaluated. When macrophages are maintained in standard culture media, both Ia antigens and accessory cell function are lost. The reacquisition of these properties follows exposure to an Ia-inducing lymphokine, for which cDNA-derived interferon-gamma may substitute. The induction of function is related quantitatively to the level of Ia expression. Moreover, both properties reflect newly expressed Ia determinants, since treatment with anti-I-A plus complement at the beginning of culture diminishes neither the subsequent level of Ia expression nor function. Treatment with anti-Mac-1 plus complement, however, reduces function commensurate with the effectiveness of macrophage depletion. Finally, we find that fixation of macrophages after exposure to antigen does not inhibit antigen presentation, indicating that metabolic activity, while required for antigen processing, is not necessary for presentation.

Modulation of human mononuclear cell responses by neutrophil-derived factors. II. Partial characterization of a neutrophil-derived lymphocyte-enhancing factor (N-LEF)

We previously reported that neutrophil (PMN)-derived factors modulated human mononuclear cell (MNC) responses. These interactions are important in understanding MNC localization, growth, and activation in inflammatory events such as occur in the rheumatoid synovium. We have partially identified and characterized a human neutrophil-derived, lymphocyte-enhancing factor (N-LEF). Highly purified PMN, devoid of MNC or platelets, were obtained by density gradient sedimentation. Supernatants (spt) were prepared from PMN phagocytosis of complement-coated zymosan particles. N-LEF was determined by [3H]TdR uptake or Ig secretion by stimulated MNC of cell lines. Neutral protease activity was quantitated by digestion of 125I-labeled Hb. Sodium dodecylsulfate (SDS) polyacrylamide gel electropheresis (PAGE) was carried out in 15% gels. We found (1) N-LEF biologic activity was cold stable, heat labile, nondialyzable, and diminished at acid pH (less than 4) or alkaline pH (greater than 10); (2) N-LEF biologic activity was abrogated by human plasma; (3) spt contained neutral protease and granule-associated but not cytoplasmic enzyme activities; (4) protease activities (for Hb, fibrin, ATEE, and Ac-Phe-BNa) were recovered from aprotinin-sepharose affinity columns and contained approximately 25,000 and approximately 28,000 molecular weight material on SDS-PAGE; (5) absorbtion of N-LEF spt on aprotinin-sepharose diminished both protease and biologic activities; and (6) N-LEF biologic activity and nonelastase neutral protease activity were found in approximately 13,000 mol wt fractions of Sephadex G100 (where cathepsin G chromatographs). Our observations suggest that phagocytosis of immune complexes by PMN induces release of a mononuclear cell enhancing factor, N-LEF, which may be an important mediator of inflammation, promoting transition from an acute to a chronic inflammatory response. Biologic properties of N-LEF are those of cathepsin G.

Immunoregulation of the mixed lymphocyte reaction by macrophage-derived factors: functional and biochemical separation of enhancing and inhibitory factors

Positive and negative immunoregulation of the mixed lymphocyte reaction (MLR) occurred through release of macrophage(MO)-derived, soluble enhancing and inhibitory factors. Macrophages, sonicated or cultured in low concentrations, produced nondialyzable, soluble factor(s) capable of enhancing the MLR; but the culture supernatant had no biologically detectable levels of Interleukin 1, Interleukin 2, or interferon. Production of enhancing supernatants was not affected by pretreatment of MO with trypsin or anti-Thy 1 antibody plus complement. In contrast, MO cultured in high concentrations yielded an inhibitory supernatant factor(s) which suppressed MLR reactivity even when MO were cultured in the presence of indomethacin. Culturing MO with proteolytic enzyme inhibitors increased the yields of the inhibitory and enhancing factors. Both factors were precipitable with ammonium sulfate and could be separated into several biologically active fractions using anion exchange chromatography.

Cyclosporin A inhibits lymphokine production but not the responses of macrophages to lymphokines

Cyclosporin A (Cs A) exerted a dose-related inhibitory effect on antigen (ovalbumin, OVA) and phytohaemagglutinin (PHA)-induced transformation of guinea-pig lymph node cells (LNC). Whereas 0.05 micrograms/ml was sufficient to depress these responses markedly, it required 100-fold this concentration of Cs A to inhibit the production of lymphocyte activating factor (LAF) by lipopolysaccharide (LPS) stimulated peritoneal macrophages. Addition of Cs A together with insoluble concanavalin A (iCon A) to LNC cultures resulted in suppressed lymphokine production, as assessed by measurement of migration inhibition factor (MIF), the generation of macrophage procoagulant activity (MPCA) and the release of lymphocyte-derived-macrophage chemotactic factor (LDCF). Cs A also inhibited MIF and procoagulant production by sensitized peritoneal exudate cells in response to antigen, at the same concentrations which blocked lymphocyte transformation. In contrast, Cs A had no direct effect on the migration of peritoneal cells from capillary tubes, or on the responses of macrophages to preformed MIF, the lymphokine inducing MPCA or LDCF. Overnight incubation of macrophages with Cs A did, however, result in mild inhibition of their basal level of procoagulant activity.

Functional aspects of B cell autonomy in human thyroid disease

To evaluate the functional aspects of B cell autonomy in human autoimmune thyroiditis we examined antigen-dependent antibody secretion using specific PFC assays for total immunoglobulin and antibodies to human thyroglobulin (hTg) and SRBC. A microculture system based on S. aureus and a macrophage-derived B cell differentiating factor provided the essential data on specific antigen induction of B cells in macrophage-depleted cultures of peripheral mononuclear cells (PMC). Anti-SRBC PFC were readily induced by SRBC-antigen in normal PMC but a significant reduction in responses was observed in patients with autoimmune thyroiditis. 8 of 10 patients had anti-hTg PFC and none were observed in normal controls. However, only 3 patients showed hTg-antigen specific B cell induction. Varying mitogen and antigen concentrations, presentation of hTg in soluble or membrane bound forms, and adding helper and macrophage cell activity failed to induce specific hTg-antigen induction in the non-responsive patients. In conclusion, anti-hTg PFC were observed in the majority of patients with autoimmune thyroiditis but such B cell secretion was not usually subject to normal immunological control mechanisms. Furthermore, the reduced anti-SRBC response in patients indicated that non-specific abnormalities were also present in this organ specific disease.

T-cell subsets induced in Listeria monocytogenes-immune mice. Ly phenotypes of T cells interacting with macrophages in vitro

Interactions of peritoneal exudate T lymphocytes from listeria-immune mice with macrophages from normal mice in the presence of heat-killed listeriae result in the induction of interleukins. The data show that Ly 1+, 23- T cells specific for listeria antigens are essential for interleukin induction and make it likely that, in addition, Ly 1+, 23+ T cells are required for optimal responses.

Accessory function of human tumor cell lines. I. Production of interleukin 1 by the human histiocytic lymphoma cell line U-937

The established human histiocytic lymphoma cell line U-937 spontaneously produced a factor with biological activity similar to that ascribed to interleukin 1 (IL 1). Actually, supernatants from U-937 cells promoted proliferation of thymocytes initiated by concanavalin A (Con A) and replaced the requirement of accessory cells for activation of highly purified circulating T lymphocytes induced by Con A. Phorbol myristate acetate (PMA) significantly increased the titers of the helper factor produced by U-937 cells as compared to that secreted by non-PMA-treated U-937 cells or PMA-stimulated P388D1 murine macrophage tumor cells. Generally U-937 cells did not secrete detectable IL 1 activity during the first 24-48 h of culture. However, after this initial period the level of IL 1 activity increased and reached a maximum at 5-6 days of culture. Finally, the helper factor released by U-937 cells had an apparent mol. wt. of 12000-15000 as determined by Sephadex G-100 chromatography and lacked interleukin 2 activity as shown by its inability to support growth of IL 2-addicted T cell lines. To our knowledge this is the first report of an established human cell line capable of producing IL 1.

Different effect of LPS-induced macrophage factor on antibody responses to TI-1 and TI-2 antigens

Effect of macrophage culture fluid (MF) on thymic independent (TI) antibody responses was examined. MF potentiated antibody responses of spleen cells to dinitrophenyl (DNP)-Ficoll and DNP-liposome, TI-2 antigens, but not to trinitrophenyl (TNP)-BA and TNP-LPS, TI-1 antigens. The enhancing effect of MF on the anti-DNP-Ficoll response was dose-dependent. Neither T cells nor macrophages were required for MF to exert the effect, suggesting that MF works on B cells directly. B cells modulated by MF in their antibody responses were indicated to be in mature B-cell subset for the following reasons: (i) the cells were in (CBA/N x BALB/c) F1 female but not in F1 male mice; (ii) the cells bore the receptors for C3 on their surface. MF was indicated to exert the enhancing effect on the antibody response by modulating the proliferation and/or early events in differentiation of B cells and not by promoting antibody secretion. The active component of the MF was indicated to be Interleukin 1.

Studies with a spontaneous murine tumour--I. Indetectibility of host immune resistance with tumour-activated elaboration of T cell stimulatory lymphokines in vitro

A spontaneous tumour SP/N-1 which arose in a BALB/c female mouse and histologically consistent with breast origin was studied in vivo and in vitro to assess host responses to the tumour. Examination by means of the established methods of tumour cell challenge and cell transfer assays following 'immunization' of the isogeneic host against the tumour failed to provide clear evidence of host recognition and reactivity. Cell transfers conducted using critical numbers of tumour cells in which tumour to spleen cell ratios of up to 1:1000 were employed did not show any sign of antitumour activity within the pretreated host spleen cells. Nor was there any evidence of host resistance when presensitized mice were challenged with graded doses of tumour cells ranging from 10(4) cells, with no take of tumours, to 5 X 10(4) cells, with total acceptance of the tumour by the challenged mice. Despite failures to demonstrate clear immune recognition of tumour by the above criteria, normal spleen cells when incubated with the tumour cells in vitro elaborated factors with stimulatory and possibly suppressive properties. At least one of these factors was shown to stimulate T cells as evidenced by stimulation of DNA synthesis in thymocytes. This could be shown readily in the presence of a submitogenic concentration of Con A.

Role of Ia antigen expression and secretory function of accessory cells in the induction of cytotoxic T lymphocyte responses against herpes simplex virus

Splenocytes from mice which have been primed in vivo with herpes simplex virus type 1 (HSV-1) can be restimulated in vitro with infectious or UV-inactivated HSV-1 to generate HSV-specific, H-2-restricted cytotoxic T lymphocytes (CTL). HSV-primed splenocytes which have been depleted of adherent cells by sequential incubation on plastic, nylon wool, and Sephadex G-10 are not able to respond with a CTL response when restimulated in vitro. A variety of Ia-positive and Ia-negative (Ia(+) and Ia(-)) cell populations were assessed for their ability to supply accessory cell functions to spleen cells which had been exhaustively depleted of adherent cells, as measured by the restoration of a CTL response to HSV-1. Of these, only those populations which included Ia(+) cells were capable of providing accessory cell function. The ineffective populations were devoid of Ia antigens, except for B lymphocytes, which are Ia(+) and still incapable of serving as accessory cells. Splenic adherent cells and resident peritoneal cells were both proficient at restoring anti-HSV CTL responses, although splenic adherent cells were clearly superior at limiting cell numbers. Neither population was capable of accessory cell activity, however, if it was pretreated with anti-Ia antiserum plus complement or if anti-Ia serum was present during induction. Peritoneal cells lose virtually all of their membrane-associated Ia antigen after a brief period of in vitro culture (24 to 48 h). Cultured peritoneal cells, as well as P388D(1) cells (normally Ia(-)), can be induced to express Ia antigens within 48 h if they are cultured with concanavalin A-stimulated spleen cell supernatants. Ia(+) P388D(1) cells without the extraneous macrophage factor are not able to restore CTL responsiveness to HSV-1 in vitro, whereas Ia(+) cultured macrophages are fully competent accessory cells. When Ia(+) P388D(1) cells were supplemented with the macrophage-derived soluble factor interleukin 1, they displayed a modest, but significant, capacity to restore secondary anti-HSV CTL responses. In addition, glutaraldehyde-fixed, HSV-1-infected Ia(+) peritoneal cells, which could not restore the CTL response alone, were capable of providing accessory cell function if extraneous interleukin 1 was provided. In contrast, Ia(-) cultured peritoneal cells, Ia(-) P388D(1) cells, and various other Ia(-) cell lines were unable to participate in the generation of CTL even in the presence of interleukin 1. The adherent cell population would therefore appear to be making at least two essential contributions to the process of CTL development, namely, the secretion of interleukin 1 and the presentation of antigen in the context of membrane-associated Ia antigen.

Intratumoral BCG therapy of transplanted head and neck tumors in strain 2 guinea pigs

The generally unfavorable prognosis associated with advanced squamous cell carcinoma in the head and neck region in humans led us to immunotherapeutic experiments with bacillus Calmette-Guerin (BCG) in inbred guinea pigs with solid growing and lymphogenous metastasizing tumors. The injection of live BCG or BCG cell wall preparation (CWP) into the planum buccale in the guinea pig led to a pronounced local inflammatory reaction. If live BCG or BCG CWP were injected into the planum buccale together with line 10 tumor cells, no growth of the tumor could be observed. Animals treated in this manner developed a tumor-specific immunity. Guinea pigs treated intratumorally with live BCG or BCG CWP in established, 6-day-old tumors of the planum buccale showed regression of the primary tumor and prevention of the development of lymph node metastases. These cured animals also developed a tumor-specific immunity. Guinea pigs with 6-day-old tumors of the planum buccale remained tumor free after surgical removal of the primary tumor and the draining submandibular and cervical lymph nodes (radical operation) whereas locally operated animals (primary tumor excision) developed lymph node metastases. Animals that were tumor free after radical surgery did not develop tumor-specific immunity. Despite insufficiently clarified mechanisms for the induction and effect of BCG immunotherapy, we can state that, with intratumoral BCG therapy, a tumor experimentally placed in the head and neck region is eliminated, regionally manifest metastases are eliminated, and specific tumor immunity can be demonstrated in successfully treated animals.

Homogeneous populations of macrophages from histiocytic lymphoma patients as a source for macrophage subpopulations which differ in immunoregulatory properties

The existence of subpopulations of macrophages which express a variety of regulatory activities of other branches of the immune system is suggested in a comparative study of a human macrophage long term culture ZI and a macrophage cell line DAB-1. Both cell cultures were derived from pleural effusions of patients with diffuse histiocytic lymphoma. DAB-1 cells were found to secrete factors which strongly suppress the response of normal T and B lymphocytes to the mitogens PHA, Con-A and pokeweed mitogen (PWM) (by 96-98%) and to stimulate the cytotoxic activity of NK cells. ZI cells secrete factors which have a mild inhibitory effect on the response of lymphocytes to the T-cell mitogens PHA and Con-A and a stimulatory effect on the response to PWM, whereas very little effect could be detected on the activity of NK cells. While DAB-1 cells form large clusters during growth in culture, and are capable of inducing the formation of lymphocyte rosettes around the tumor cells, ZI cells grow as a homogeneous monolayer and could not be shown to form such rosettes. The differences in the behavior of the two cell populations suggest that the malignant transformation may have affected different subsets of macrophages in each case. Cells from histiocytic lymphoma patients may therefore be a source for homogeneous subpopulations of macrophages and their isolation and propagation in culture is one approach by which such subsets can be defined characterized and classified. The biological characterization of macrophage subsets may also be of clinical importance since a transformed subset with broad suppressory activities may lead to a violet and rapidly deteriorating course of disease, as was in the case of the patient from whom the DAB-1 cell line was derived.

The biology of SAA: identification of the inducer, in vitro synthesis, and heterogeneity demonstrated with monoclonal antibodies

Continued studies of the macrophage-derived mediator of SAA synthesis (SAA Stimulating Factor) confirm our previous observations that SAASF copurified with leukocytic pyrogen (LP) and lymphocyte activating factor (LAF). Moreover, new data demonstrate three separate isoelectric points for human LP-LAF-SAASF each of which possess the three biological activities. During the purification of 15,000 MW LP from crude stimulated mononuclear cell supernatants, only those fractions with pyrogenic activity in rabbits caused augmented stimulation of lymphocytes (LAF) and induced SAA synthesis in mice. Purified human LP stimulated isolated mouse hepatocytes in vitro to synthesize SAA in a dose-responsive manner. Colchicine treatment of hepatocytes led to decreased secretion of SAA into the medium and to an intracellular accumulation of SAA. Messenger RNA was isolated from the livers of endotoxin-stimulated mice and translated in a wheat-germ cell-free system. A major product was identified at 13-14,000 MW. Immunoprecipitation with anti-mouse AA identified several bands on autoradiography of polyacrylamide gels. These larger SAA precursors may account for the previously noted heterogeneity of human SAA, comprising at least 6 SAA isomers, of similar molecular weight but different solubility and electrophoretic charge characteristics. Two monoclonal antibodies (IgM-K and IgG1-K) have been prepared using standard cell hybridization techniques. They are directed at the variable COOH terminal region of SAA since they detect differences between the 6 human SAAs but do not react with human, monkey, dog or mouse AA proteins, human AP, C-reactive protein, IgG nor albumin. These antibodies will be useful in examining the origin, structure and function of SAA.

Ontogeny of murine macrophages: functions related to antigen presentation

Macrophage function in neonates was dissected into four components: antigen uptake and catabolism, cytotoxicity, antigen presentation, and the production of the lymphostimulatory molecule interleukin-1 (also called thymocyte mitogenic protein or lymphocyte-activating factor). The uptake and catabolism of 125I-labeled Listeria monocytogenes was equivalent in macrophages from adult and neonatal mice. However, interactions between macrophages from neonates, heat-killed Listeria organisms, and immune T lymphocytes were impaired, and no cytocidal macrophages capable of killing tumor cells were generated. Previous studies with cells from adult mice had established that the development of cytocidal macrophages required Ia-bearing, antigen-presenting macrophages and histocompatibility at I-A between macrophages and T cells. To circumvent this requirement for antigen-presenting macrophages, an assay was used in which lymphokine was added directly to the macrophages from neonates. Strong cytocidal activity resulted. Thus, our studies confirmed that macrophages from neonates present antigen poorly but can acquire cytocidal function provided that the need for antigen-presenting function is bypassed. Similar conclusions were reached for the secretion of interleukin-1. Macrophages from neonates spontaneously secreted as much mediator as macrophages from adults, and the secretion was increased after the ingestion of heat-killed Listeria organisms or endotoxin. However, the marked increase in interleukin-1 production that follows antigen-macrophage-lymphocyte interaction was best seen in macrophages from adults. Macrophages from neonates could be activated to ingest C3b-coated sheep erythrocytes.

Accessory cells unrelated to mononuclear phagocytes and not of bone marrow origin

The induction and regulation of immune responses require the participation of cells which maintain lymphocyte viability, promote necessary cellular interactions, secrete immunoregulatory molecules and present antigen. These are accessory cells, and their function is not antigen-specific. Classically, cells of the mononuclear phagocyte lineage have been considered to be the major accessory cell population in most immune responses. More recently, other cell types, such as Langerhans cells of the skin and dendritic cells of the lymphoid organs, have also been shown to be effective. This article reviews the evidence that additional cell types, such as endothelial cells or fibroblasts, serve an accessory role in immune responses.

Specific cellular stimulation in the primary immune response: experimental test of a quantized model

Dose-response and dose-suppression curves have been measured for the primary immune response in mice, in vivo and in vitro, by using size-fractionated linear polymers of acrylamide substituted with hapten. The results are in general agreement with a simple theory based on the premise that the specific primary immunological response is quantized at some fundamental and limiting step, requiring a minimum number of linked antigen receptors for response.

Growth regulation by macrophages

The evidence reviewed here indicates that macrophages, either acting alone or in concert with other cells, influence the proliferation of multiple types of cells. Most of the data indicate that these effects are mediated by soluble macrophage-elaborated products (probably proteins) although the role of direct cell-to-cell contacts cannot be ruled out in all cases. A degree of success has been achieved on the biochemical characterization of these factors, but such work has been hampered by the factors low specific activity in conditioned medium and the lack of rapid, specific assays. It is our belief that understanding the growth-regulating potential of macrophages is an important and needed area of research.

Antigen presentation and regulatory functions of human monocytes in the in vitro response of lymphocytes against purified protein derivative of tuberculin (PPD)

Monocyte functions in the primary and secondary proliferative responses of human lymphocytes against purified protein derivative of tuberculin (PPD) have been studied. By applying the antigens either directly to the responding cells or on antigen-treated autologous monocytes, it was possible to distinguish between two different monocyte functions: antigen presentation and regulation. Their helper function in lymphocyte proliferation was found in cell-free supernatants of autologous and allogeneic monocytes and was expressed better in the secondary rather than in the primary responses. The antigen-presenting function of monocytes, however, was found to be more substantial in the primary response of lymphocytes. These results suggest that macrophage dependency of certain immune functions should be considered in regard to the various functions of macrophages, since at least quantitative differences for each of the macrophage functions were found in the primary and secondary proliferative responses.