Studies on the role of lymphocyte-activating factor (Interleukin 1) in antigen-induced lymph node lymphocyte proliferation

Benefits of posttransplantation monitoring of interleukin 6 in lung transplantation

To determine the predictive diagnostic value of interleukin 6 (IL-6) monitoring in lung and heart-lung transplants, we measured posttransplantation serum IL-6 levels in 17 adult lung or heart-lung transplant recipients. Posttransplantation IL-6 elevation patterns were classified into 4 groups: serum IL-6 level remained negative throughout the monitoring period (group 1; n = 1; 6%); several sharp spikes with normal baseline (group 2; n = 9; 53%); persistently high level of serum IL-6 (group 3; n = 3; 18%); and several sharp spikes of serum IL-6 elevation with abnormally high baseline (group 4; n = 4; 24%). One patient without an elevation of IL-6 (group 1) did not experience any episodes of rejection or infection. Nine patients in group 2 had 19 IL-6 spikes, 13 of which were associated with histopathologically or clinically diagnosed rejection, 3 with acute bronchitis, and 1 with diffuse alveolar damage. Three patients in group 3 had persistent infections including cytomegalovirus infection, toxic megacolon, and repeated bacterial infection during the monitoring period, and 4 in group 4 died within 3 months after transplantation. From this study it appears that a spiked elevation of IL-6 could have a predictive value in diagnosing rejection, and persistently high levels of IL-6 indicate the presence of infection. Thus, IL-6 monitoring is beneficial for lung transplant recipients.

IL-1 production by human thymic dendritic cells: studies on the interrelation with DC accessory function

Thymic dendritic cells (DC) have been proposed to play a critical role in the generation of immunocompetent T lymphocytes. Since IL-1 is widely considered to be an important second signal in T cell stimulation, we have studied the ability of isolated human thymic DC to produce IL-1. Using the EL4/CTLL conversion assay standardized with recombinant IL-1 beta (rIL-1 beta), we demonstrate that upon LPS-stimulation thymic DC produce small amounts of IL-1 as compared to peripheral blood monocytes (PBM). In contrast with PBM, DC IL-1 production is not influenced by indomethacin. IL-1 activity was detected in the supernatants of DC cultures from all thymuses tested, although quantitative variability was noted among individual thymic donors. The specificity of the active factor was confirmed by neutralization assays with anti-IL-1 beta mAb. On the other hand, we demonstrate that rIL-1 beta cannot substitute for nor amplify the accessory function of thymic DC and that anti-IL-1 beta mAb fails to block the DC accessory function. Thus we conclude that IL-1 beta might not be a major factor for the efficient DC accessory function toward mature thymocytes recently demonstrated in our laboratory. Of interest, IL-1 beta was also detected in the supernatants of DC-thymocyte cocultures in the absence of mitogenic factor, suggesting that thymocyte contacts can constitute a sufficient signal to induce DC to produce IL-1. These observations indicate that human thymic DC represent an intrathymic source of IL-1 whose role in thymocyte proliferation or maturation remains to be understood.

Soluble factors in tolerance and contact sensitivity to DNFB in mice. X. IL-2 is the activation signal mediating release of synthesized suppressor factor

Two signals are required for the in vitro activation of Lyt2+ T suppressor cells (Ts) from mice tolerized with 2,4-dinitrobenzene sulfonate (DNBS) to produce soluble suppressor factors (SSF) which suppress the transfer of contact sensitivity to dinitrofluorobenzene (DNFB). Recognition of DNP/class I MHC (signal one) stimulates the Ts to synthesize SSF. Release of SSF requires a soluble mediator (signal two) produced by the interaction of L3T4+ T cells from tolerant mice with I-A on metabolically functional cells in the DNP-presenting cell population. The purpose of this study was to examine the nature of this second Ts activation signal. Coculture of tolerant spleen cells and glutaraldehyde-fixed (Glu-) DNP-labeled spleen cells (DNP-SC) resulted in the synthesis but not release of SSF. Addition of either IL-1 or IL-2 to these cultures induced SSF release. Treatment of such cultured cells with the anti-murine IL-2 receptor antibody PC 61.5.3 blocked the IL-2- and IL-1-stimulated release of SSF. Release of SSF was also blocked when tolerant cells were cultured with (unfixed) DNP-SC in the presence of a monoclonal anti-IL-2 antibody. IL-2 but not IL-1 was able to stimulate the Ts to release synthesized SSF in the absence of L3T4+ TH activity. First, addition of IL-2 to cocultures of tolerant cells and DNP-presenting I-A- cells induced release of the synthesized SSF, whereas addition of IL-1 did not. Second, IL-2 also stimulated SSF release in cocultures of L3T4+ T cell-depleted tolerant cells and Glu-DNP-SC, whereas IL-1 did not. Tolerant cells pretreated with IL-2 and then washed were able to synthesize and release SSF upon culture with Glu-DNP-SC. Pretreatment of tolerant cells with IL-1 did not stimulate SSF release upon subsequent culture with Glu-DNP-SC. These results indicate that the Lyt2+ Ts from DNBS-tolerant mice express IL-2 receptors and IL-2 is the lymphokine which induces the Ts to release synthesized SSF. Thus, IL-2 provides a differentiative signal during the functional activation of these regulatory T cells.

Augmentation by interleukins of the antibody response to a conjugate vaccine against Haemophilus influenzae b

Interleukins have been recognized as potential adjuvants for use during vaccination. The immunogenicity of some poorly immunogenic bacterial capsular polysaccharides have been improved by conjugation to a protein carrier. Augmentation of the immune response to these glycoconjugates, however, may be realized in the presence of interleukins. The antibody response to one such vaccine which comprises a oligosaccharide derived from the capsule of Haemophilus influenzae type b coupled to CRM197 (HbOC) can be augmented in this manner. A suboptimal dose (0.1 microgram) of HbOC and varying concentrations of IL-1 alpha or IL-1 beta (10(2) - 5 x 10(5) U) were injected intramuscularly at 0 and 2 weeks into Swiss Webster mice. Vaccines were also formulated with and without aluminum phosphate. Antibody to the oligosaccharide was determined by Farr assay. In 3/3 experiments, IL-1 alpha enhanced primary and secondary antibody responses whereas with IL-1 beta, only a slight increase in the primary antibody response was seen but enhanced secondary responses were observed. Thus, IL-1 alpha and to some extent IL-1 beta enhanced the primary and secondary antibody responses to a glycoconjugate vaccine.

Interleukin-1-induced promotion of T-cell differentiation in mice immunized with killed Listeria monocytogenes

We studied the effects of administration of recombinant interleukin-1 alpha (rIL-1 alpha) to mice after immunization with killed Listeria monocytogenes cells on the promotion of the functional differentiation of T cells in vivo. Mice immunized with killed L. monocytogenes were unable to express cell-mediated immunity to specific antigen in vivo, as determined by delayed-type hypersensitivity (DTH) and acquired cellular resistance (ACR), and splenic T cells obtained from such mice were unable to respond to rIL-2 and specific antigen and to produce IL-2 after antigenic restimulation in vitro. When rIL-1 alpha was given to mice after immunization with killed bacteria. T cells became capable of responding to rIL-2 and specific antigen in vitro. These functions of T cells were similar to those from mice immunized with viable listeriae. Moreover, using a local passive transfer system, it was found that effector T cells mediating DTH but not ACR to L. monocytogenes were generated in mice treated with rIL-1 alpha after immunization with killed bacteria. These T cells were able to produce macrophage chemotactic factor but not macrophage-activating factor or gamma interferon in vitro in response to stimulation with specific antigen. These results suggest that in vivo administration of rIL-1 alpha facilitates the maturation of antigen-specific T cells mediating DTH and that different effector T cells mediating DTH or ACR are involved in cell-mediated immunity to L. monocytogenes.

Interferon-gamma potentiates antibody affinity in mice with a genetically controlled defect in affinity maturation

Interferon-gamma (IFN-gamma), the tetrapeptide tuftsin and the synthetic nonapeptide from interleukin-1 beta (IL-1 beta) (amino acids 163-171) have previously been shown to act on macrophages and/or T cells and to enhance antibody titres to T cell-dependent antigens. The ability of these immunomodulatory agents to potentiate antibody affinity in addition to antibody titre has been studied in a line of mice that fail to demonstrate normal maturation of antibody affinity (low N/M mice). The results presented here confirm that each of the agents potentiate antibody levels following simultaneous injection with a T cell-dependent antigen but demonstrate that only IFN-gamma is able to enhance antibody affinity in these mice. The observation that IFN-gamma can enhance both antibody affinity and antibody levels suggests that it could be an important adjuvant for vaccine use.

Enhanced immunogenicity of a sequence derived from hepatitis B virus surface antigen in a composite peptide that includes the immunostimulatory region from human interleukin 1

The effect on immunogenicity of coupling the immunostimulatory nonapeptide sequence (residues 163-171) from human interleukin 1 beta (IL-1 beta) to a small immunogen was examined. A 21-amino acid sequence spanning positions 12-32 on the large protein of hepatitis B surface antigen was chosen as a model. Three peptides were synthesized corresponding to the IL-1 beta-derived sequence [peptide IL-(163-171)], the hepatitis B surface antigen-derived sequence [peptide S1-(12-32)] and a composite peptide that included both these sequences separated by a spacer of two glycine residues [peptide S1-(12-32)-IL-(163-171)]. In an in vitro thymocyte proliferation assay, both peptides S1-(12-32)-IL-(163-171) and IL-(163-171) showed comparable activity, whereas peptide S1-(12-32) was inactive. Groups of five to seven mice each from C3H/CH, BALB/c, SJL/J, and C57BL/6 strains were immunized with equimolar amounts of either peptide S1-(12-32), peptide S1-(12-32)-IL-(163-171), or a mixture of peptides S1-(12-32) and IL-(163-171), and sera were screened for anti-S1-(12-32) antibodies. In all strains, peptide S1-(12-32)-IL-(163-171) elicited an increased primary and secondary anti-S1-(12-32) antibody response compared to the other two groups. Further, peptide S1-(12-32)-IL-(163-171) also induced an increased number of responders to primary immunization, though the number of responders was quantitative in all groups following secondary immunization. At least part of the enhanced immunogenicity of the S1-(12-32) sequence in peptide S1-(12-32)-IL-(163-171) appears to be due to augmented T-helper cell activity. These results suggest that coupling of the immunostimulatory IL-1 beta-derived sequence in tandem with an immunogen may confer inbuilt adjuvanticity.

Temperature-mediated processes in immunity: differential effects of low temperature on mouse T helper cell responses

A low culture temperature of 27 degrees C inhibited mouse primary in vitro anti-hapten plaque-forming cell responses to a thymus-dependent (TD) antigen (Ag) (trinitrophenyl-keyhole limpet hemocyanin, TNP-KLH). In contrast, the magnitudes of secondary responses to TNP-KLH or primary responses to a thymus-independent (TI) Ag (TNP-lipopolysaccharide (LPS)) were unaffected. The low-temperature-sensitive step in the primary TD response occurred relatively early and preceded interleukin 2 (IL-2) secretion. Furthermore, the low-temperature-induced suppression could be obviated (rescued) by recombinant IL-2 or IL-4, but not by IL-1. Thus, the low temperature appeared to inhibit the function of virgin Th cells by preferentially affecting T cell-derived interleukin synthesis/secretion and not other cellular activities. These results also imply fundamental differences between the activation requirements of memory and virgin Th cells.

Effect of interleukin-1 on the size distribution of cartilage proteoglycans as determined by sedimentation field flow fractionation

The effect of interleukin-1 (IL-1) on the size distribution of cartilage proteoglycans was studied using sedimentation field flow fractionation (SdFFF), a rapid, high-resolution technique for the separation of proteoglycan monomers and aggregates. During incubation of cartilage in control media, 35S-prelabeled proteoglycan was lost primarily from proteoglycan present in the monomer form; aggregates were conserved. In the presence of IL-1, both 35S-proteoglycan monomers and aggregates were lost, suggesting that IL-1 increases the susceptibility of aggregates to loss from the cartilage matrix. Evaluation of uronic acid as a measure of net change in proteoglycan content indicated that IL-1 causes a net decrease in both monomers and aggregates. Kinetic studies suggested that aggregates are degraded to monomers which then diffuse out of the matrix. Incorporation of [35S]sulfate into cartilage proteoglycans following exposure to IL-1 showed that synthesis of monomers and aggregates is inhibited similarly. SdFFF is a valuable technique for studying proteoglycan metabolism. With its use, changes in proteoglycan monomer and aggregate populations can be detected in response to cytokines such as IL-1.

Effects of atelocollagen on the wound healing reaction following palatal gingivectomy in rats

Collagen membrane preparations have been manufactured with the aim of enhancing wound healing following periodontal surgery. After cross-linking by various processing methods (with ultraviolet radiation or hexamethylenediisocyanate) and to various extents, atelocollagen membranes were applied into dissection sites within palatal gingival tissue. Applied atelocollagen was histopathologically compared with applied lyophilized porcine dermis (LPD) and controls in rats, with regard to the time course of healing. The atelocollagen-applied group showed more satisfactory regeneration of the epithelium and connective tissue in an artificially created gingival defect than did the control group or the LPD-applied group. Epithelial downgrowth along the root surface was significantly suppressed by the use of atelocollagen. In addition, the post-operative inflammatory reaction and foreign body giant cell reaction subsided rapidly after surgery in the atelocollgen-applied group. Our results show that the use of atelocollagen membrane in periodontal wounds should be the method of choice.

Independent effects of interleukin-1 on proteoglycan breakdown, proteoglycan synthesis, and prostaglandin E2 release from cartilage in organ culture

Exposure of bovine nasal cartilage in culture to interleukin-1 (IL-1) leads to a time- and concentration-dependent stimulation of proteoglycan breakdown and prostaglandin E2 (PGE2) release, and to inhibition of proteoglycan synthesis. The threshold levels of IL-1 required for initiating these effects were different, and IL-1 was 10 times more potent in inhibiting synthesis than in stimulating breakdown of proteoglycan. Kinetic studies indicated that the effects on proteoglycan metabolism occurred earlier (16-24 hours) than those for PGE2 release (48 hours). Selective effects were observed with inhibitors. Nonsteroidal antiinflammatory drugs blocked PGE2 production in response to IL-1, but had no effect on proteoglycan metabolism, and the antiarthritic drugs that blocked IL-1-stimulated breakdown augmented the inhibition of proteoglycan synthesis. We suggest that the effects of IL-1 on proteoglycan breakdown, proteoglycan synthesis, and PGE2 release are mediated by independent post-receptor mechanisms.

Cell-mediated immunity to chemically xenogenized tumors. II. Evidence for accessory function and self-antigen presentation by a highly immunogenic tumor variant

To determine whether antigen-presenting ability might be involved in the superior immunogenicity of chemically xenogenized tumors over that of parental cells, we tested a murine lymphoma line xenogenized by a triazene derivative for expression of Ia antigens, ability to present soluble antigen in vitro, and production of factor(s) active in a mouse thymocyte assay. Results showed that Ia antigens, absent on nonimmunogenic parental L5178Y cells, were expressed on a xenogenized, highly immunogenic tumor variant (clone D), as detected by immunofluorescence. While the ability of parental cells to stimulate lymphocyte proliferation in vitro was lost on removal of Ia+ cells from the responder population, considerable augmentation of reactivity was observed upon depletion of Ia+ cells from the population of splenocytes responding to the xenogenized cells. Under these conditions, stimulation was blocked by anti-Ia antibodies, or an anti-L3T4 reagent or antibodies to the novel antigenic determinants induced by xenogenization. In addition, no stimulating activity was observed following exposure of clone D cells to glutaraldehyde or lysosomotropic agents such as chloroquine and ammonia. When the ability of clone D cells to present ovalbumin in vitro was assayed, it was found that the xenogenized cells could present the soluble antigen to specifically primed lymphocytes. Moreover, clone D cells could substitute for splenic adherent cells in the proliferative reaction of splenocytes to concanavalin A. Finally, when the supernate from clone D-cell culture pulsed with phorbol myristic acetate was tested in a mouse thymocyte assay, considerable IL-1-like activity was disclosed.

Heterogeneity of helper/inducer T lymphocytes. I. Lymphokine production and lymphokine responsiveness

Antigen-specific, Ia-restricted helper/inducer T lymphocytes consist of subsets that can be distinguished by lymphokine secretion. One, called Th1, secretes IL-2 and the other, termed Th2, produces BSF-1/IL-4 in response to stimulation by lectin or antigen receptor signals, and each uses the respective lymphokine as its autocrine growth factor. Cloned lines representing Th2 cells proliferate in response to both IL-2 and their autocrine lymphokine, BSF-1/IL-4, but this proliferation is dependent on the synergistic costimulator activity of the monokine, IL-1. In contrast, Th1 clones proliferate only in response to IL-2, are unresponsive to BSF-1/IL-4, and their growth is unaffected by IL-1. These response patterns are not attributable to variations in culture conditions but apparently reflect intrinsic properties of the two T cell subsets. Moreover, the unresponsiveness of Th1 cells to BSF-1/IL-4 may be related to lower levels of expression of surface receptors for this lymphokine. These results may explain the observed heterogeneity among bulk populations of T cells in terms of lymphokine responsiveness and requirement for accessory factors (costimulators). In addition, our findings suggest that IL-2, unlike BSF-1/IL-4, is a fully competent growth factor that is potentially involved in antigen-independent expansion of bystander T cells present at sites of immune stimulation.

The role of interleukin 1 and 2 in generation of acquired resistance against mouse typhoid infection afforded by dialyzable factor from Salmonella typhimurium

Dialyzable factor (DF) prepared from a ribosomal fraction of Salmonella typhimurium was tested for its ability to induce interleukin 1 (IL 1) and 2 (IL 2) production, in relation to acquired resistance, after an intraperitoneal injection of DF. IL 1 production in vitro by peritoneal macrophages of DF-treated mice reached the maximum 4 days after injection, at the time when the nonspecific local resistance via macrophages directly activated with DF became apparent (Kita et al, Microbiol. Immunol. 28:807, 1984). Concanavalin A-induced IL 2 production by splenocytes of DF-treated mice reached the maximal level between days 6 and 8, and it could be enhanced even on day 14. Antigen-induced blastogenic responses of splenocytes from DF-treated mice reached the maximal level 14 days after treatment. Although DF did not show the mitogenic activity to normal splenocytes, T cells of DF-treated mice could respond to S. typhimurium. On the contrary, T cells of normal mice could respond to heat-killed cells of S. typhimurium when they were cultured with macrophages which had been directly stimulated in vitro with DF. Furthermore, T cells from DF-treated mice could respond to antigens of different species of bacteria, and especially to Listeria monocytogenes. These results suggest that T cells of DF-treated mice, being at the intermediate stage of activation via monokines including IL 1 which is produced by macrophages stimulated with DF, are able to proliferate immediately after the administration of challenging organisms as a second signal, and also that the specificity of the response may be defined by the challenging organisms.

Epstein-Barr virus-transformed lymphoblastoid cell lines as antigen-presenting cells and "augmenting" cells for human CMV-specific Th clones

The ability of Epstein-Barr virus-transformed lymphoblastoid cell lines (LCL) to present human cytomegalovirus (HCMV) antigen to a panel of HCMV-specific T helper (Th) clones was evaluated. Among the seven Th clones studied, only one clone (SP-CN/T3-16) proliferated well to HCMV presented by both autologous mononuclear cells (MNC) and LCL, and one clone (SP-CN/T3-9) proliferated significantly better to HCMV presented by autologous LCL than by autologous MNC. The majority of the HCMV-specific Th clones tested (five out of seven) responded much better to HCMV presented by MNC than to HCMV presented by LCL. The mechanism(s) responsible for the inefficiency of LCL to present HCMV to certain clones was studied. Our results suggested that the defect of LCL is not due to insufficient interleukin 1 production, insufficient MHC class II molecule expression, nor an inhibitory mechanism or factor. In this report, we also demonstrate that by adding a minimum amount of LCL along with MNC as antigen-presenting cells (APC), one can restimulate and expand Th clones much more efficiently than by using MNC alone as APC.

Evaluation of alveolar macrophages in normals and individuals with active pulmonary sarcoidosis for the spontaneous expression of the interleukin-1 beta gene

We have evaluated the hypothesis that the presence of large numbers of activated helper/inducer T lymphocytes in the lungs of individuals with active pulmonary sarcoidosis is associated with the exaggerated release of interleukin-1 (IL-1) by alveolar macrophages. Evaluation of media from unstimulated cultured sarcoid alveolar macrophages failed to detect IL-1 activity. When parallel cultures of sarcoid and normal alveolar macrophages were stimulated with lipopolysaccharide (LPS), they released similar amounts of IL-1 activity. Using a highly specific polyclonal anti-IL-1 beta antibody and flow cytometry to evaluate cell-associated IL-1 beta, analysis of fresh alveolar macrophages from patients with active sarcoidosis and normal individuals revealed no detectable cell-associated IL-1 beta, but IL-1 beta was present when macrophages from sarcoid patients and normals were stimulated with LPS. Similar observations were made using immunoblot analysis of cell lysates of the same unstimulated and stimulated macrophages. Finally, Northern analysis of alveolar macrophages for IL-1 beta mRNA transcripts demonstrated minimal, but equivalent, amounts of IL-1 beta in both normal and sarcoid macrophages, as compared to the much larger quantities present in LPS-stimulated alveolar macrophages. Thus, while alveolar macrophages of individuals with sarcoidosis are clearly capable of expressing the IL-1 beta gene, these findings suggest that altered expression of the IL-1 beta gene by alveolar macrophages does not play a central role in the exaggerated lung T-cell activation characteristic of sarcoidosis.

Induction of interferon-gamma production and Ia expression by interleukin 1 in bone marrow culture cells

Colony-stimulating factor-induced bone marrow (BM) cultures are a good source of antigen-presenting macrophages. However, they failed to present antigen to T cell clones when antigen was introduced as a short pulse only. Adding interleukin 1 (IL1) to BM culture cells before antigen pulse restored their antigen-presenting activity concomitant to a 2-10-fold increase in Ia antigenicity. We performed a series of experiments to test the mechanism of this IL1-induced activation. Our findings suggest that IL1 influences Ia expression and antigen-specific T cell proliferation by inducing interferon-gamma (IFN-gamma) production. IFN-gamma is produced in this system probably by residual Thy-1-positive cells in the BM cell culture.

Interleukin 1 and protein kinase C activator are dissimilar in their effects on Il-2 receptor expression and Il-2 secretion by T lymphocytes

T lymphocytes respond to mitogenic stimulation by expressing the receptor for interleukin 2 (Il-2) and secreting Il-2; once the receptor is expressed, Il-2 induces these cells to proliferation. In the present report using mouse T lymphocytes, thymocytes, and the lymphoma cell line EL4, we studied receptor expression and Il-2 secretion as early parameters for T-lymphocyte activation in response to ionomycin, concanavalin A (Con A), 12-O-tetradecanoyl-phorbol 13-acetate (TPA), and interleukin 1 (Il-1). Il-1 is required for mitogenic response of lymphocyte preparations that are rigorously depleted of macrophages. On its own, Il-1 had very little effect on Il-2 secretion and Il-2 receptor expression by T lymphocytes. TPA strongly synergized with ionomycin both for Il-2 secretion and for Il-2 receptor expression whereas Il-1 did not. Il-1 required the simultaneous presence of ionomycin and TPA to have any demonstrable effect on T lymphocytes from spleen and on thymocytes. However, on EL4 cells which were also partially responsive to TPA alone, Il-1 showed strong synergy with TPA to induce Il-2 secretion and Il-2 receptor expression. The effect of Il-1 on EL4 cells was dose dependent where increasingly higher concentrations of Il-1 in the presence of a fixed concentration of TPA caused higher percentage of EL4 cells to become Il-2 receptor positive. The present results suggest that Il-1 does not cause its effect on T lymphocytes via the same mechanism of protein kinase C activation that has been proposed for TPA.

Antigen presentation by hapten-specific B lymphocytes. III. Analysis of the immunoglobulin-dependent pathway of antigen presentation to interleukin 1-dependent T lymphocytes

The ability of antigen-specific murine B lymphocytes to present antigen to a normal (nontransformed) antigen-specific, interleukin (IL)1-dependent T cell clone and to heterogeneous T lymphocytes was investigated. Hapten-specific lymphocytes present protein antigens to both the D10G.4.1 T cell clone and heterogeneous immune T cells. When the antigen bears an epitope recognized by the specific B cell, the subsequent presentation of this antigen is 10(2)-10(4)-fold more efficient, as compared to the same, but nonhaptenated protein. The requisite B lymphocyte binds hapten, is radiosensitive and is nonadherent to plastic. The hapten-specific antigen presentation is blocked by antibodies to the surface Ig receptor, while the presentation of unmodified protein is unaffected. These observations are identical to our findings in studies of B cell antigen presentation to T-T hybridomas and therefore demonstrate the generality of the immunoglobulin-dependent pathway of presentation. However, in contrast to the results with T-T hybridomas, the specific B lymphocytes are necessary, but not sufficient, to activate IL 1-dependent T cells. A third cell is required for both B lymphocyte immunoglobulin-dependent and nonspecific antigen-presentation. This cell is radioresistant, plastic adherent and of low density. The requirement for this third cell can be circumvented by supplementing cultures with highly purified IL 1. These results demonstrate that the remarkably efficient ability of B lymphocytes to present antigen is operative with factor-dependent T lymphocytes. Furthermore, conventional accessory cells also appear to play a role in this process, which is consistant with their known requirement in antigen-specific T-B interactions in the generation of antibody responses.

A prostaglandin-mediated suppressive activity of cord as compared to maternal or other adult adherent cells in OKT3 antibody-induced proliferation

In a previous study we reported that cord blood lymphocytes show lower OKT3 responses as compared to their mothers and to other, unrelated adults. In the study reported here, we investigated the interactions between lymphocytes and adherent accessory cells in OKT3-stimulated cultures of newborn (cord), maternal, and other adult peripheral blood mononuclear leukocytes (PBML) and determined the following. (1) Removal of adherent cells (AC), by two cycles of plastic adherence or by nylon wool columns, impaired the OKT3-induced proliferation of maternal/adult cells, but significantly enhanced the OKT3 responsiveness of cord cells. (2) Addition of indomethacin, and other prostaglandin (PG) synthesis inhibitors, caused a more than twofold augmentation of cord PBML OKT3 responses, but had only a small, if any, enhancing effect on maternal/adult PBML. Cord PBML cultures deprived of AC were no longer enhanced by indomethacin. (3) Exogenous PGE2 (1.4 X 10(-6) through 1.4 X 10(-9) M) strongly inhibited OKT3-induced proliferation of maternal, cord, and adult PBML, at a wide range of antibody concentrations (5-100 ng/ml). However, an obvious difference in the extent of PG-mediated inhibition was observed among these three populations, and the order of PG sensitivity, from most to least sensitive, was cord greater than maternal greater than adult. (4) Purified interleukin-1 (IL-1) could not replace the accessory function of AC in the OKT3-induced proliferation of maternal/adult lymphocytes. In contrast, IL-1 increased by greater than 50% the OKT3 responsiveness of cord PBML in the absence, but not in the presence, of cord monocytes. Our observations strongly argue for a distinct, predominantly suppressive function of cord monocytes as compared to maternal/adult monocytes in OKT3-induced mitogenesis, and indicate prostaglandins as major mediators of this suppression.

Comparison of accessory cell functions of endothelial cells and monocytes: IL-2 production by T cells and PFC generation

It has been previously shown that endothelial cells (EC) can modulate T-cell responsiveness by mimicking monocyte (AC) function in several different in vitro systems. We now report that EC and AC differ quantitatively in their ability to provide help for IL-2 generation and T-cell induced B-cell differentiation into immunoglobulin secreting cells (ISC). Equal numbers of EC were deficient when compared to AC for promoting ISC generation, but exceeded AC for IL-2 production. Adding optimal numbers of EC drive non-adherent cell cultures to produce more than twice as much IL-2 as adding any number of AC. Furthermore, small numbers of EC were capable of modulating ongoing immune responses when added to cultures containing AC. IL-2 production by PBM was doubled by the addition of enough EC to comprise only 3% of the total culture. EC do not just mimic monocytes in immune responses, but modulate these responses in unique ways.

Role of alveolar macrophage- and lung T cell-derived mediators in pulmonary sarcoidosis

The process of granuloma formation in the lung is mediated by an intimate interaction between macrophages and T cells, and this interaction provides the appropriate environment for granuloma formation and the development of fibrosis. Much of this process of granuloma formation and fibrosis appears to be triggered by the release of immune mediators by alveolar macrophages and lung T cells.

The role of self-Ia antigens in the murine mixed lymphocyte response

Mouse splenic macrophages (M phi) were tested for their ability to potentiate in vitro allogeneic mixed lymphocyte response (MLR) of highly purified syngeneic responder T cells against allogeneic M phi. It was shown that even extremely low numbers of M phi syngeneic to the responder T cells were able to induce significantly stronger MLR. This potentiating effect was demonstrated to be expressed via the self-Ia antigens present on the surface of syngeneic M phi. The functional involvement of self-Ia antigens was substantiated by two approaches: (a) by using monoclonal antibodies specific for I-region determinants of the responder haplotype M phi and (b) by setting up MLR cultures with stimulator M phi of (responder X stimulator) F1 origin which express both self- and allo-Ia antigens. The results obtained in this study demonstrate that the presentation of self-Ia antigens, in conjunction with the recognition of allo-major histocompatibility complex antigens, are required for in vitro primary MLR.

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.

The suppressive effect of tape-stripping treatment of guinea-pig skin on the induction of contact sensitivity by intradermal injection of haptenated epidermal cells

Contact sensitivity (CS) to 2,4-dinitrochlorobenzene (DNCB) was produced in inbred JY1-strain guinea pigs by the intradermal injection of epidermal cells (ECs) prepared from DNCB-painted skin (DNP-ECs). When the site of DNP-EC-induced CS was pretreated by tape stripping, the rate and intensity of the challenge reactions to DNCB were diminished. The ability of DNP-ECs to induce CS returned to normal when normal peritoneal macrophages together with DNP-ECs were administered into the stripped skin. Normal ECs had a similar effect. Using either anti-Ia antiserum and complement or allogeneic ECs (strains 2 and 13), Ia-positive cells among the ECs (presumably Langerhans cells) were found to be essential for the recovery of CS. Tape-stripping treatment also resulted in the development of immunological tolerance, as assessed by subsequent painting with a sensitizing dose of DNCB. These findings suggest that the immunological function of the mononuclear-phagocyte system in the dermis may be impaired when the epidermal surface is markedly disturbed by tape-stripping treatment.

Search for class II major histocompatibility complex molecular involvement in the response of Lyt-2+ cytotoxic T lymphocyte precursors to alloantigen

A possible requirement for class II major histocompatibility complex (Ia) molecules in the initial activation of cytotoxic T lymphocyte precursors (CTLp) for allocytotoxic responses was investigated. To avoid possible interaction with other alloreactive cell types, a highly purified population of Lyt-2+ splenocytes was used as a source of CTLp. In the light of preliminary results indicating that Lyt-2+ CTLp, even in the presence of interleukin 2 (IL2), could best be triggered into mature CTL in vitro by cells known to be Ia+, we examined whether an interaction of CTLp with Ia antigens (either on syngeneic accessory cells or on allogeneic stimulators) played a role in the development of allocytotoxicity. Results from experiments done with C57BL/6 Lyt-2+ splenocytes co-cultured with P815 stimulator cells and IL 2 showed that the early activation of CTLp was independent of Ia+ syngeneic accessory cells: (a) flow microfluorometry analysis of the responder population at the beginning or after 1 or 3 days of co-culture did not reveal the presence of Ia+ cells; (b) procedures for removal of residual Ia+ cells or of dendritic cells from the responder population before co-culture did not affect the development of cytotoxicity; (c) co-culture with monoclonal antibodies against syngeneic Iab antigens did not inhibit the CTLp activation. By comparing an Ia+ P815 tumor line with its Ia- clone as allogeneic stimulator cells, it was found that the CTLp activation was also independent of Ia alloantigen on the stimulator cells. The response against both the Ia+ and the Ia- stimulator cell types was not inhibited by monoclonal anti-L3T4 present in the co-culture, indicating that these responses were not affected by residual L3T4 helper cells.

Monoclonal antibodies against human Ia antigens stimulate monocytes to secrete interleukin 1

The monoclonal antibodies (mAb) DA6.147, DA6.164, and HIG.48 against human Ia antigens, but not the W6/32 mAb against human class I major histocompatibility complex antigens or the anti-monocyte OKM1 and 63D3 mAb, stimulated monocytes to secrete interleukin 1 (IL-1). IL-1 was measured by its property of promoting the production of interleukin 2 (IL-2) by phytohemagglutinin-treated LBRM-33 clone 1A5 cells. IL-1 activity induced by anti-Ia antibodies could be detected 24 hr after initiation of the cultures and reached its highest levels at days 3-4 of culture. Concentrations of 1 microgram/ml or higher of the anti-Ia antibodies induced monocytes to secrete significant levels of IL-1 activity. The anti-Ia mAb induced Ia-bearing but not Ia-negative monocytes to secrete IL-1. Both Ia-positive and Ia-negative monocytes produced IL-1 activity under the stimulus of lipopolysaccharide. It is concluded that the DA6.147, DA6.164, and HIG.48 mAb stimulate secretion of IL-1 by interacting Ia antigens on monocytes. The data support the view that besides serving as restricting elements for recognition of foreign antigens by T cells, Ia antigens may also function as transducer elements.

Suppression of antigen- and mitogen-induced proliferation of bovine lymphocytes by excretory-secretory products of Oesophagostomum radiatum

Excretory-secretory products (ESP) isolated from in vitro-grown stage-3 to -4 larvae of Oesophagostomum radiatum were found to inhibit both the in vitro antigen-specific proliferation of keyhole limpet hemocyanin- and ovalbumin-primed lymphocytes and the proliferation induced by the T-cell mitogen concanavalin A. As little as 50 ng of ESP protein per culture resulted in 50% reductions of subsequent proliferative responses. Antigen-induced responses were 100 to 1,000 times more sensitive to inhibition than were mitogen-induced responses. The inhibitory activity was found to affect the induction of proliferation as evidenced by the observation that complete inhibition was seen when ESP were added to cultures within the first 24 h. ESP were found to have no inhibitory activity when added 72 h after the initiation of the cultures. The inhibition was not a result of a direct action upon macrophages because pulsing of adherent cells with ESP had no more effect on a subsequent proliferative response than did a pulsing of the culture vessel itself. The inhibitory activity eluted from high-pressure liquid chromatography columns in the same fractions as protein standards with molecular weights of 25,000 to 35,000. Of special interest is the fact that this inhibitor of the expansion of immunoreactive clones of lymphocytes is found associated with the stages of parasites most intimately associated with host tissues, namely larval stages 3 and 4.

Effect of monoclonal antibodies (MoAb) to class I and class II HLA antigens on lectin- and MoAb OKT3-induced lymphocyte proliferation

We have examined the effect of several monoclonal antibodies (MoAb) to monomorphic determinants of class II HLA antigens, and MoAb to monomorphic determinants of class I HLA antigens and to beta-2-microglobulin (beta 2-mu) on lectin- and MoAb OKT3-induced proliferation of human peripheral blood mononuclear cells (PBMNC) and cultured T cells (CTC). Some, but not all, anti-class II HLA MoAb inhibited the proliferative response of PBMNC to MoAb OKT3 and pokeweed mitogen (PWM). The degree of inhibitory effect varied considerably. This effect was not limited to anti-class II HLA MoAb since anti-class I HLA MoAb and anti-beta 2-mu MoAb also inhibited MoAb OKT3- or PWM-induced proliferative responses. In contrast, the response of PBMNC to phytohemagglutinin (PHA) and concanavalin A (Con A) was not blocked by any anti-class II HLA MoAb. However, some anti-class II HLA MoAb also inhibited the proliferative response of CTC plus allogeneic peripheral blood adherent accessory cells (AC) to PHA or Con A as well as to MoAb OKT3 or PWM. This may be attributable to the substantially greater class II HLA antigen expression by CTC than by fresh lymphocytes. Pretreatment of either CTC or AC with anti-class II HLA MoAb inhibited OKT3-induced proliferation. In contrast, pretreatment of CTC, but not AC, with anti-class I HLA MoAb inhibited the proliferative response of CTC to OKT3. Pretreatment of CTC with anti-class I HLA MoAb inhibited PHA-, Con A and PWM-induced proliferation, to a greater degree than the anti-class II HLA MoAb. It appears as if lymphocyte activation by different mitogens exhibits variable requirements for the presence of cells expressing major histocompatibility determinants. Binding of Ab to membrane markers may interfere with lymphocyte-AC cooperation, perhaps by inhibiting binding of mitogens to their receptors or by interfering with lymphocyte and AC function. We also have examined the role of class II HLA antigens on CTC by depleting class II HLA-positive cells. As expected, elimination of class II HLA-positive AC with anti-class II HLA MoAb plus complement caused a decrease in proliferation of CTC in response to all the mitogens tested. In contrast, elimination of class II HLA-positive CTC was shown to clearly increase proliferation of CTC, perhaps because this may deplete class II HLA-positive suppressor cells.

A mouse ear reaction for assessment of human lymphocyte immunocompetence

A mouse ear reaction for testing cell mediated immunity of human lymphocytes using the local graft-versus-host reaction assay is described. Five million human mononuclears were locally injected into the ears of immune suppressed NZW mice. The reaction mounted was quantitated by determining the 125I-Iodo-Deoxyuridine (125I-UdR) incorporation in both ears. The ratio of 125I-UdR incorporation, of the injected to that of the non-injected ear (GVHR index), 7 days after lymphocyte injection, served as an accurate measure for the extent of the reaction. Only normal human mononuclears and purified, separated normal human T lymphocytes mounted a local graft-versus-host reaction. Whereas normal human B lymphocytes, chronic lymphatic leukemia B lymphocytes, mononuclears from patients with transitional cell carcinoma of the bladder, irradiated normal human mononuclears, mouse syngeneic mononuclears, or human erythrocytes gave no positive reaction. These experiments demonstrate that this assay can be used to quantitate an in-vivo specific graft-versus-host reaction.

Interleukin-1-like activities in synovial fluids of patients with rheumatoid arthritis and traumatic synovitis

Interleukin-1 (Il-1)-like activity in biological fluids was measured by their ability to rectify the Il-1-dependent lymphokine production of highly purified T lymphocytes to a recall antigen. Il-1-like activity was found in 9 of 11 synovial fluid (SF) specimens from patients with rheumatoid arthritis (RA) but only in 2 of 11 paired RA sera. In traumatic synovitis, low Il-1-like activity was recorded in 5 of 9 SF specimens, and a similar low activity was found in sera of 4 of these patients. The Il-1-like activity was partly absorbed by an anti-Il-1 antibody. The presence of Il-1 in the SF of patients with RA suggests in vivo activation of monocytes/macrophages.

Interleukin 1, a mediator of immunoadjuvant peptidoglycans

Bacterial peptidoglycans and the synthetic analog muramyl dipeptide possess various immunomodulating properties (adjuvant effect, increase of resistance to infectious agents and to tumor growth). They are able to induce B cell activation and to stimulate macrophages to produce monokines such as Interleukin 1 (IL 1). IL 1 plays an essential role in immune response. It promotes thymocytes maturation and Interleukin 2 secretion by antigen sensitive T cells, which in turn triggers regulatory T cells. Moreover, it is involved in the proliferation and differentiation of B cells. There is a correlation between the immunoenhancing effect of PG of a definite structure and their ability to induce IL 1 secretion. Non-adjuvant PG were inactive. This suggests that one of the major mechanisms of action of adjuvant PG could be the stimulation of IL 1 synthesis.

The differential effects of hydrocortisone on activation and tolerance induction in human T lymphocyte clones

The in vitro effects of hydrocortisone on T cell activation and tolerance induction were investigated using human influenza virus immune T cell lines and clones. Hydrocortisone at 10(-9) to 10(-6) molar concentrations was able to inhibit the antigen induced but not the T cell growth factor (TCGF) mediated proliferative response of both the lines and clones. However, hydrocortisone was able to inhibit TCGF production by cloned T cells. The proliferative response of cloned T cells to intact influenza virus A/Texas/1/77 was more markedly inhibited by equivalent concentrations of hydrocortisone than was the response of that clone to a 24 amino acid sequence (p20) of the haemagglutinin molecule implying that hydrocortisone may also act at the level of antigen processing. Furthermore hydrocortisone was able neither to induce T cell tolerance alone nor to inhibit antigen specific tolerance induction. However, hydrocortisone did lower the antigen threshold for tolerance induction. The possible mechanisms of hydrocortisone activity in the modulation of T cell regulation in autoimmune disease are discussed.

Normal human alveolar macrophages obtained by bronchoalveolar lavage have a limited capacity to release interleukin-1

Interleukin-1 (IL-1) is a mediator released by stimulated mononuclear phagocytes that is thought to play an important role in modulating T and B lymphocyte activation as well as in contributing to the febrile response and other inflammatory processes. Circulating mononuclear phagocytes, blood monocytes, readily release IL-1 when stimulated. However, the ability of lung mononuclear phagocytes, alveolar macrophages, to dispose of the large daily burden of inhaled antigens without stimulating an inflammatory response suggests that the release of IL-1 by alveolar macrophages may differ significantly from that of blood monocytes. To evaluate this hypothesis, normal autologous alveolar macrophages, obtained by bronchoalveolar lavage, were compared with blood monocytes for their ability to release IL-1 in response to a standard stimulus, lipopolysaccharide (LPS). Alveolar macrophages were found to be at least 1,000 times less sensitive to LPS than blood monocytes. Furthermore, alveolar macrophages released significantly less IL-1 than blood monocytes (26 +/- 11 vs. 128 +/- 21 U/10(6) cells X 24 h, respectively, after stimulation with 10 micrograms/ml of LPS, P less than 0.001). This difference was not due to the release of substances by macrophages, which inhibited lymphocyte proliferation in response to IL-1, or to degradation of IL-1 by macrophages. Culturing macrophages in the presence of indomethacin and dialysis of macrophage supernatants did not affect the difference, and culturing macrophages with monocytes did not decrease detectable IL-1 activity from the monocytes. The IL-1 produced by the two cell types was indistinguishable by anion-exchange chromatography, gel filtration, and isoelectric focusing. In addition, consistent with the findings for alveolar macrophages, macrophages generated by the in vitro maturation of blood monocytes were also deficient in their ability to release IL-1. These findings suggest that if the population of alveolar macrophages obtained by bronchoalveolar lavage represents the total in vivo population of alveolar macrophages, although normal human macrophages are capable of IL-1 release, they are relatively limited in this ability, and this limitation seems to be linked to the maturational state of the mononuclear phagocyte. These observations may explain, in part, the ability of alveolar macrophages to clear the airspaces of foreign antigens without extensive activation of other pulmonary inflammatory and immune effector cells.

Membrane Ia expression and antigen-presenting accessory cell function of L cells transfected with class II major histocompatibility complex genes

To study the relationship between the structure and function of Ia antigens, as well as the physiologic requirements for antigen presentation to major histocompatibility complex-restricted T cells, class II A alpha and A beta genes from the k and d haplotypes were transfected into Ltk- fibroblasts using the calcium phosphate coprecipitation technique. Individually transfected genes were actively transcribed in the L cells without covalent linkage to, or cotransformation with, viral enhancer sequences. However, cell surface expression of detectable I-A required the presence of transfected A alpha dA beta d or A alpha kA beta k pairs in a single cell. The level of I-A expression under these conditions was 1/5-1/10 that of Ia+ B lymphoma cells, or B lymphoma cells expressing transfected class II genes. These I-A-expressing transfectants were tested for accessory cell function and shown to present polypeptide and complex protein antigens to T cell clones and hybridomas in the context of the transfected gene products. One T cell clone, restricted to I-Ak plus GAT (L-glutamic acid60-L-alanine30-L-tyrosine10), had a profound cytotoxic effect on I-Ak- but not I-Ad-expressing transfectants in the presence of specific antigen. Assays of unprimed T cells showed that both Ia+ and Ia- L cells could serve as accessory cells for concanavalin A-induced proliferative responses. These data indicate that L cells can transcribe, translate, and express transfected class II genes and that such I-A-bearing L cells possess the necessary metabolic mechanisms for presenting these antigens to T lymphocytes in the context of their I-A molecules.

T cell clones interacting with accessory and T helper cells for a proliferative response

The requirement for cell interactions in T cell activation has been studied with two continuously in vitro growing T cell clones. These clones are specific for minor histocompatibility antigens, are H-2K restricted, and one clone is functionally a cytolytic T lymphocyte. Both can proliferate when interleukin 2 is added to the cultures, but for continuous growth they require irradiated spleen cells carrying the specific minor histocompatibility antigen and the restricting H-2. In this study we show that for proliferation the clones require at least two cell populations in the stimulator spleen, one is a splenic-adherent cell (SAC), the other a T cell. The SAC are plastic adherent, Thy-1-, Ia+. The T cells are nylon wool nonadherent, Thy-1+, Lyt-1+2- and Ia-. Cell mixing experiments of stimulator cells (all were done with H-2-syngeneic cells), depleted of either SAC or T cells confirm the requirement for a specific interaction between these two cell types and the T clone. Neither SAC, syngeneic with the T clone when mixed with T cells of the stimulator type, nor T cells syngeneic with the clone added to stimulator SAC, can induce an optimal proliferative response. Such a response is obtained only if both cell types, SAC and T cells, are of the stimulating genotype. This suggests that, in addition to an interaction of clonal T cells with SAC, a specific recognition at the T cell level between T stimulator and T clone is necessary. The interaction of the T clones with stimulator SAC and T cells leads to an activation, mediated by antigen recognition, of all three cell populations. Since we also show that each of the stimulator cell types are impaired by ultraviolet light irradiation, we conclude that factor production by SAC and T helpers is the final prerequisite for clonal expansion.

Heterogeneity of macrophage populations in human lymphoid tissue and peripheral blood

Human lymphoid tissue and peripheral blood leukocytes were stained with six monoclonal antibodies directed against monocyte/macrophage populations. The staining pattern described by each of these monoclonal reagents was compared with the distribution of morphologically distinguishable tissue macrophages. The results show that there exists considerable heterogeneity of tissue macrophages based on the expression of surface and/or cytoplasmic antigens; furthermore, the distribution of cells bearing particular antigenic determinants is associated with distinct regions in normal lymphoid tissue. Double staining methods demonstrated that these antibodies bind to different, as well as to identical, macrophage populations. OKM-1 antibody binds predominantly to sinus histiocytes and tingible body macrophages. The Leu M-1 reagent stains interdigitating reticulum cells, while the KiM-4 antibody labels follicular dendritic cells. Leu M-3 antibody identifies cells predominantly in the germinal center, and histiocytes lining the sinuses. Both CM-1 and BRL-M.1 appear to stain tissue macrophages distributed throughout the lymphoid tissue.

Demonstration of interleukin 1 activity in apparently homogeneous specimens of the pI 5 form of rabbit endogenous pyrogen

Rabbit mononuclear cells from oil-induced peritoneal exudates were purified by centrifugation on Percoll gradients, suspended in tissue culture medium, and stimulated with opsonized Staphylococcus epidermidis. The supernatants from these macrophages caused fever when injected intravenously into rabbits (endogenous pyrogen [EP] activity). The EP activity was contained in two protein fractions, with pIs of 7.3 and ca. 5.0. The same fractions caused mouse thymocytes to incorporate tritiated thymidine when incubated in vitro with small quantities of phytohemagglutinin (interleukin 1 [IL-1] activity). The pI 5.0 form of EP was purified to apparent homogeneity by sequential use of ammonium sulfate precipitation, gel filtration, ion-exchange chromatography, hydrophobic chromatography, and high-resolution isoelectric focusing. EP and IL-1 activities were not separable by any of these procedures. Active fractions from isoelectric focusing were analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Only one band was visible as judged by a silver staining method, and IL-1 activity could be recovered by renaturing eluates from the same region of sodium dodecyl sulfate gels run in parallel. An estimate of specific activity was made by comparing the intensity of stained bands of EP with the intensity of bands containing known quantities of lysozyme or RNase. By this criterion, the specific activity of purified pI 5 EP was between 17,000 and 58,000 degrees C U/mg of protein, and the specific activity in terms of IL-1 was between 59 million and 360 million U per mg of protein. These observations suggest that both EP and IL-1 activities can be expressed by a single molecular species. The implications of this coincidence are discussed. It was also shown that highly purified pI 5 EP obtained from macrophages stimulated in the presence of 14C-labeled amino acids contained significant 14C radioactivity. This suggests that the pI 5.0 EP, like the pI 7.3 form, was synthesized de novo from amino acid precursors.

Interleukin 1 can replace monocytes for the specific human B-cell response to a particulate antigen

It is shown that the anti-trinitrophenyl (TNP) response of human B cells to trinitrophenyl polyacrylamide beads (TNP-PAA) is monocyte dependent. This response is abolished by extensive adherent cell depletion and restored by the addition of monocytes. The optimal response is obtained with 3% monocytes, higher numbers being suppressive. Supernatants from muramyl dipeptide (MDP)-activated monocytes can restore the response of monocyte-depleted preparations even when cells are cultured at suboptimal concentration. A partially purified preparation of interleukin (IL-1) has a comparable restorative ability. The following arguments suggest that monocytes do not function as antigen-presenting cells for this particulate antigen: (i) antigen-pulsed monocytes induce neither an anti-TNP response nor a specific T-cell proliferative response; (ii) allogeneic monocytes function as well as autologous monocytes to restore the response of nonadherent cells; (iii) HLA-DR-negative cells from the human leukemia cell line K562 can replace monocytes for this response. Monocyte supernatants do not replace T cells for the response of B-enriched lymphocytes, showing that T cells are directly involved in B-cell activation.

Langerhans cell production of interleukin-1

Epidermal Langerhans cells (LC) are related to certain cells of the monocyte-macrophage lineage and to other dendritic cells. While epidermal LC and macrophages bear receptors for the Fc portion of IgG, other dendritic cells do not. However, unlike human dendritic cells from peripheral blood, LC bear the antigen against which the OKT6 antibody is directed. Within the skin this antibody binds only to LC or indeterminate cells. Functionally LC and dendritic cells can present antigen to sensitized T cells and are capable of stimulating allogenic T cells. Since lymphokines are thought to play an important role in T-cell activation and since LC are potent stimulators of antigen-specific T-cell proliferation, we investigated whether LC could produce interleukin-1 (IL-1). Our initial studies revealed that whole epidermal cell suspensions comprised of LC, keratinocytes, and melanocytes produce a factor that is similar to macrophage-derived IL-1. We termed this factor epidermal cell-derived thymocyte-activating factor ( ETAF ). Using a panning technique we obtained a highly enriched (up to 97%) population of LC which constitutively produced significant IL-1-like activity. Using an antibody against the monocyte-derived leukocytic pyrogen (LP) which has been shown to inhibit IL-1 activity, we were able to inhibit IL-1 activity from LC-enriched cultures. The results of this study indicate that within the epidermis there are at least two cell populations, keratinocytes and LC, that can constitutively secrete potentially important soluble immunostimulatory factors.

Partial characterisation of the high and low molecular weight forms of P388D1-derived interleukin 1

The murine macrophage-derived cell line P388D1 secretes the lymphokine interleukin 1 (IL-1) when stimulated by a variety of agents. When stimulated by bacterial lipopolysaccharide (LPS) the cells release IL-1 in both high and low molecular weight (m.w.) forms. The proportion of high m.w. IL-1 is reduced when IL-1-containing supernatants are concentrated by ammonium sulfate precipitation subsequent to hollow-fiber filtration. The high m.w. form can be converted to the low m.w. form by proteolysis, reduction and alkylation, or chromatography in a dissociating solvent. The low m.w. form remains as such, even when reconcentrated in fetal calf serum-containing medium. The high m.w. form thus likely consists of a complex between low m.w. IL-1 and another protein secreted by the P388D1 cell line.

Immunoregulation in experimental schistosomiasis. II. Soluble egg antigen-induced chronic spleen cell augmentation of baseline lymphocyte reactivity

Spleen cells from mice harboring infections of Schistosoma mansoni for 20 weeks exposed to Con A or to soluble schistosome egg antigenic preparation (SEA), treated with Mitomycin C (Mc), and cocultured with spleen cells from either normal or infected mice caused an augmented baseline [3H]TdR incorporation by the otherwise unstimulated responder cells. This regulation required an in vitro induction phase. SEA-exposed, Mc-treated normal spleen cells had no effect on responder cell cultures. SEA-stimulated, Mc-treated chronic spleen cell augmentation was effective on responder cell populations from either normal mice or mice infected with S. mansoni for 8 weeks. Augmentation was most pronounced when assayed on cells from infected mice assayed over a 5-day incubation. In addition, it is demonstrated that these Con A- and SEA-elicited activities are mediated by soluble mediators which lack H-2 restriction.

Accessory functions and mutual cooperation of murine macrophages and dendritic cells

In this study the antigen-presenting functions of murine splenic dendritic cells (DC) and macrophages (M phi) have been compared. DC and M phi were pulsed with keyhole limpet hemocyanin (KLH) and found to contain approximately 92% and 50% Ia-positive cells, respectively. The two KLH-pulsed cell populations had almost equal ability to stimulate KLH-immune T cells. The antigen-presenting functions of DC and M phi were compared by measuring the capacity of KLH-pulsed, UV-irradiated cells, which failed to secrete interleukin 1 (IL 1), to stimulate KLH-immune T cells when each culture was supplemented with an equal amount of exogenous IL 1. The antigen-presenting capacity of DC was always greater than that of M phi. Coculturing of the two kinds of accessory cells upon KLH pulsing resulted in enhanced antigen-presenting capacity of the mixture relative to the same number of each accessory cell type. That is, collaboration between them in antigen presentation was clearly observed. However, direct contact between DC and M phi was not obligatory for this collaboration. Furthermore, we found that different types of soluble factors released by each of them might be responsible for the collaboration. In addition, supernatants of concanavalin A-stimulated spleen cells augmented the antigen-presenting function of only M phi. Finally, the antigen-presenting function of DC and M phi from athymic mice was almost the same as that from control mice.