Antibody formation initiated in vitro. II. Antibody synthesis in x-irradiated recipients of diffusion chambers containing nucleic acid derived from macrophages incubated with antigen

The road to the discovery of dendritic cells, a tribute to Ralph Steinman

While it was known by the 1960s that lymphocytes mediated adaptive immunity, it was unknown how antigens stimulated lymphocytes. Between 1967 and 1973, we reported that a rare cell type in murine spleen cells took up antigen and were obligatory for T cell dependent and independent antibody responses. We referred to them as A cells or the third cell type. In 1973, Ralph Steinman and Zanvil Cohn described a rare cell type in murine spleen cells which was phagocytic but had dendrite like protrusions; they named them dendritic cells (DCs). In 1978, Steinman reported that DC were required for mixed lymphocyte reactions. From that time until recent death, Ralph Steinman pursued relentlessly in his laboratory and through collaborations around the world the role and function of DC in immunity. In passing, using a monoclonal antibody supplied by Steinman, we showed that A cells were the same as DC.

Decisions about dendritic cells: past, present, and future

A properly functioning adaptive immune system signifies the best features of life. It is diverse beyond compare, tolerant without fail, and capable of behaving appropriately with a myriad of infections and other challenges. Dendritic cells are required to explain how this remarkable system is energized and directed. I frame this article in terms of the major decisions that my colleagues and I have made in dendritic cell science and some of the guiding themes at the time the decisions were made. As a result of progress worldwide, there is now evidence of a central role for dendritic cells in initiating antigen-specific immunity and tolerance. The in vivo distribution and development of a previously unrecognized white cell lineage is better understood, as is the importance of dendritic cell maturation to link innate and adaptive immunity in response to many stimuli. Our current focus is on antigen uptake receptors on dendritic cells. These receptors enable experiments involving selective targeting of antigens in situ and new approaches to vaccine design in preclinical and clinical systems.

Immunogenicity of Ribonucleic Acid Preparations Obtained from Salmonella typhimurium

Mice immunized with purified whole-cell ribonucleic acid (RNA), RNA from the bacterial "particulate" fraction, and ribosome-associated RNA obtained from Salmonella typhimurium were found to be resistant to subsequent challenge infection with virulent salmonellae. Chemically, the immunogenic nucleic acid fractions contained from 1 to 3% "contaminant" material defined (based on the mean of 19 different preparations) as protein (0.24%), deoxyribonucleic acid (0.43%), methyl pentose (0.64%), hexose (1.58%), and undefined carbohydrate (0.76%). Heptoses and lipoidal material were not detectable in any of the immunogenic preparations examined. Physically, the nucleic acid preparations, after analytical ultracentrifugation, exhibited three boundaries similar to those reported elsewhere in comparable systems: 4 to 5S, 16S, and 23S. An evaluation of the immunity induced by the ribosome-associated RNA established that the immune response was (i) comparable to that induced 15 days postimmunization with live salmonellae and by ribosomal vaccines, but greater at 30 days postimmunization than that in mice immunized with attenuated salmonellae; (ii) dependent on the quantity of immunogen administered; (iii) dependent on the size of the infective inocula; (iv) inhibited at 15 but not at 30 days postimmunization when the immunogenic nucleic acid preparations were incorporated into Freund's incomplete adjuvant, (v) reduced or lost by dialysis in relatively high or low immunizing doses, respectively; and (vi) unaffected by enzymatic treatment of the preparations with trypsin, deoxyribonuclease, Pronase plus pancreatic ribonuclease, or pancreatic ribonuclease alone. The possible mode of action of ribosome-associated RNA in inducing an immune response to subsequent challenge infection with the homologous organism is discussed.

EFFECT OF ACTINOMYCIN D ON RNA SYNTHESIS AND ANTIBODY FORMATION IN THE ANAMNESTIC RESPONSE IN VITRO

Antibody synthesis in anamnestic lymphoid cells, measured by incorporation of leucine-C¹⁴ into specific antibody, was inhibited at moderate concentrations of actinomycin D. This was accompanied by marked inhibition of synthesis of RNA as measured by incorporation of H³-cytidine monophosphate. However, at low concentrations of actinomycin D, antibody synthesis was unaffected or even increased while RNA synthesis continued to be inhibited. The results obtained suggest that messenger RNA for antibody synthesis, either because it is relatively stable or present in excess, does not become a limiting factor until its synthesis is maximally inhibited. Puromycin, an inhibitor of amino acid coupling, abolished antibody synthesis in low concentration. 6-Mercaptopurine had no effect on the synthesis of antibody or RNA even at high concentration. The data obtained support the view that antibody synthesis follows pathways similar to those utilized for the formation of other types of proteins.

THE LYMPHOD TISSUES AND IMMUNE RESPONSES OF NEONATALLY THYMECTOMIZED MICE BEARING THYMUS TISSUE IN MILLIPORE DIFFUSION CHAMBERS

Neonatally thymectomized mice were implanted intraperitoneally at 7 days of age with Millipore diffusion chambers containing either embryonic or neonatal thymus tissue. Mice which received either empty diffusion chambers or no further treatment following neonatal thymectomy served as controls. In contrast to these controls, most of the mice implanted with thymus-filled chambers gained weight satisfactorily, did not develop a wasting syndrome, and had the capacity to produce serum antibodies in response to sheep erythrocytes and to reject allogeneic skin grafts. Lymphoid follicles were present in the lymph nodes, spleen, and intestinal tract of the implanted mice but most still showed some diminution in the population of lymphocytes in both blood and tissues. Control thymectomized mice had markedly depleted lymphoid tissues and low peripheral blood lymphocyte levels. The tissue recovered after 1 to 2 months from the diffusion chambers showed only epithelial-reticular cells but no lymphoid cells. It is suggested that a humoral factor produced by the thymus epithelial-reticular complex may be responsible for endowing lymphoid cells with immunological competence.

THE FORMATION AND PROPERTIES OF POLIOVIRUS-NEUTRALIZING ANTIBODY. IV. NORMAL ANTIBODY AND EARLY IMMUNE ANTIBODY OF RABBIT ORIGIN: A COMPARISON OF BIOLOGICAL AND PHYSICOCHEMICAL PROPERTIES

Rabbit sera were found to possess neutralizing activity (normal antibody) to polioviruses and Coxsackie B viruses. This normal antibody showed high specificity in cross-neutralization and absorption tests. It was associated with heat-stable, mercaptan-sensitive, 19S γ₁-β-macroglobulins, which formed weak complexes with the viral antigen. In rare instances, sera with normal macroglobulin antibody, also contained very low activity which was due to 7S γ₂-globulins. The neutralization of poliovirus by normal 19S γ₁-β-antibody appeared to follow first order kinetics, and the thermodynamic parameters of this reaction were the same as those of serological reactions employing immune antibody. The electrophoretic mobility, sedimentation properties, sensitivity to mercaptan, thermostability, and avidity of normal and early (up to day 3) immune antibodies to poliovirus were similar, but differed in several respects from those of late immune antibodies. Thus, the available evidence suggested, that earlier reported differences between normal and immune antibodies reflected differences between antibodies of diverse physicochemical properties rather than between normal and immune antibodies per se. It is proposed that the normal macroglobulin antibody is associated with an immunological response to repeated stimulation with minute amounts of antigen.

ANTIGENICITY OF POLYPEPTIDES (POLY ALPHA AMINO ACIDS). XII. IMMUNOLOGICAL STUDIES WITH A NEW GROUP OF SYNTHETIC COPOLYMERS

A new group of synthetic random polymers of alpha-L-amino acids has been studied for immunogenicity. With the glutamic acid and alanine copolymers, those consisting of almost equimolar amounts of the two (G(60)A(40) and G(40)A(60)) were effective antigens in rabbits whereas those with higher glutamic acid contents (G(75)A(25), G(90)A(10)) were poor antigens. The substitution of alanine by valine or leucine (G(75)V(25) and G(80)Leu(20)) produced copolymers which were poor antigens in rabbits but effective in guinea pigs. L(70)A(30), although capable of "non-specifically" precipitating serum proteins, was shown not to be antigenic in either rabbits or guinea pigs. The introduction of alanine into glutamic acid and lysine polymers (GLA series) enhanced the immunogenicity of the terpolymers, i.e., GLA30 > GLA20 > GLA10 > GL. The mechanism by which this may be accomplished is discussed as possibly being related to the reduction of the interactions between glutamyl and lysyl residues which allows the carboxyl groups to act as strong immunogenic determinants.

STUDIES ON ARTIFICIAL ANTIGENS. II. THE ANTIGENICITY IN GUINEA PIGS OF ARSANILIC ACID CONJUGATES OF COPOLYMERS OF D- OR L-ALPHA-AMINO ACIDS

An effort was made to immunize guinea pigs with arsanilic acid conjugates of copolymers of D- and L-α-amino acids; ASD-GAT and ASL-GAT. An immune response was observed only in the case of ASL-GAT. Antibodies specific for the arsanilic acid hapten were produced which could also react with ASD-GAT or ASGPA. These findings indicate that the proper metabolism of the antigen may be essential to the induction of the immune response.

ANTIGENICITY OF POLYPEPTIDES (POLY ALPHA AMINO ACIDS). 13. IMMUNOLOGICAL STUDIES WITH SYNTHETIC POLYMERS CONTAINING ONLY D- OR D- AND L-ALPHA-AMINO ACIDS

It has been demonstrated that polymers consisting solely of D-alpha-amino acids are not immunogenic in rabbits, guinea pigs, man, and mouse, whereas the same polymers of L-alpha-amino acids are very effective antigens. This has been attributed to the importance of metabolizability of a polymer in contributing to its immunogenicity. In the glu-lys-ala series of polymers, the immunogenicity of a polymer of 2 L-amino acids and a D-amino acid appears to be governed by the immunogenicity of the 2 L-amino acids. However, some of the specificity may be directed towards configurations containing the D-amino acid. It has been noted that injections of rabbits with polymers of D-amino acids has resulted in a reduced response against the isomeric L polymer.

Antigen “Suicide”: A Preliminary Study on the Induction of Specific Anti-Immunoglobulin Immunological Suppression in Vivo, Using Radiolabeled Immunoglobulin as “Lethal” Antigen

The effectiveness of immunodiagnosis and immunotherapy is limited when xenogeneic antibodies are used, due to the host's anti-immunoglobulin response. We have attempted to specifically suppress the immune response to the immunogen (immunoglobulin) administered. The concept of antigen “suicide” was used, where the antigen (immunoglobulin) was suitably radiolabelled and administered to animals. The question asked was whether immunocompetent cells that specifically interact with the radiolabeled immunogen, would be lethally irradiated and thus become inactivated rather than stimulated. When mice where primed with111Indium-labelled polyclonal human IgG (specific activity 15 mCi/mg), they responded 13% less than control animals (p = 0.0485). This suppression was IgG-specific, since all animals responded similarly to a control antigen (human albumin). However, a second boost of the same111Indium-labelled preparation (specific activity 7 mCi/mg) did not show any statistically significant immunosuppression. In addition, rabbits primed with125Iodine-labelled mouse monoclonal antibody (specific activity 180mCi/mg) and boosted with the same unlabelled monoclonal antibody, showed a similar anti-mouse antibody response with the ones that received only unlabelled preparation twice. We conclude that the concept of antigen “suicide” may be effective for the induction of specific unresponsiveness; when immunoglobulins are radiolabeled with111Indium at high specific activities, the desired state of specific immune suppression may be induced.

Immune RNA therapy as an effective adjuvant immunotherapy after surgery: an animal model

Transfer of tumor immunity as adjuvant cancer therapy has been a topic of intense interest. We have examined the efficacy of various combinations of surgery, xenogeneic immune RNA, xenogeneic normal RNA, tumor vaccine, and nonspecific splenocytes as adjuvant therapy for B16 melanoma in the C57BL/6J mouse system. B16 melanoma was transplanted by trocar into the right hind limb of 6-week-old mice. The tumors were readily palpable on the ninth day posttransplantation. The tumors were amputated at that time under mild anesthesia. Immune RNA was prepared by hot phenol extraction from immune sheep spleens. Various combinations of immune RNA, normal RNA, and tumor antigen, with or without normal mouse spleen cells, were administered every other day for a total of 10 injections. The survival and mode of death was followed up to 120 days. All mice without any treatment died within 30 days. Immunotherapy had no effect on the survival of mice that did not have surgical therapy. Individual group comparisons between mice that underwent surgery only and mice that had surgery plus immune RNA immunotherapy revealed a striking statistical improvement (P less than 0.01). Comparing all groups that received amputation plus various combinations of adjuvant immunotherapy showed no statistical difference in survival. However, immune RNA appears somewhat superior to normal RNA or antigen only. It appears that adjuvant immune RNA immunotherapy following surgical excision in the B16 melanoma model significantly improves survival and retards the spread of metastases.

In vivo and in vitro effects of xenogeneic immune ribonucleic acid in patients with advanced renal cell carcinoma: a phase I study

Based upon demonstration in our laboratory of repeated prevention of pulmonary metastases by adjuvant immune ribonucleic acid in animal preparations, xenogeneic immune ribonucleic acid was given in a phase I study to patients with advanced renal cell carcinoma. Six patients were treated with intravenous infusions of autologous lymphocytes incubated in vitro with immune ribonucleic acid extracted from splenocytes of guinea pigs immunized with the patient's own tumor. Serial peripheral blood lymphocytes were obtained during and after each treatment with immune ribonucleic acid for in vitro evaluation of cell-mediated cytolysis by 51chromium release assay and 125iodine iododeoxyuridine assay against allogeneic renal cell carcinoma targets and melanoma targets. Neither toxicity nor enhancement of tumor growth was observed. All patients demonstrated significantly increased cell-mediated cytolysis against allogeneic renal cell carcinoma targets but no change against melanoma targets. Increased cell-mediated cytolysis could be demonstrated in individual blood samples after incubation with immune ribonucleic acid. Further, progressive in vivo effect was demonstrated in in vitro assay of serial peripheral blood lymphocytes before each successive exposure to immune ribonucleic acid. Increased cell-mediated cytolysis persisted in peripheral blood lymphocytes up to 9 months after therapy. Although without controls 1 patient had complete response and 2 patients had partial responses (8 to 18 months). Two patients had stabilization of the disease for 3 to 4 months and 1 patient had progression of cerebral metastases. One patient is alive 24 months after therapy. These results would favor the institution of a randomized prospective trial in patients with advanced renal cell carcinoma or lesser tumor burdens.

Antigen restricted hybridization between antigen primed macrophage and thymic RNA

Antigen primed macrophage and thymic RNAs hybridize in an antigen restricted fashion. Thymic RNA complementary to the antigen-stimulated macrophage RNA can be obtained from mice inoculated with antigen three days earlier. The ratio of thymic and macrophage RNAs for the optimal hybridization was 50 : 1. The optimal incubation time for hybridization was 32 hours at 60 degrees C. Hybrid RNAs were insensitive to various kinds of RNase. The 31p Fourier transform nuclear magnetic resonance spectra identified hybrid RNA molecules form single stranded RNS's.

Immunotherapy with RNA in cancer

The effect of I-RNA therapy was studied in a B16 melanoma-C57BL/6J mouse system. After having primary B16 isografts excised, mice receiving syngeneic lymphocytes incubated in vitro with specific guinea pig B16 I-RNA showed significantly improved survival as compared to control mice receiving untreated lymphocytes. This therapeutic effect was tumor specific and RNase sensitive. Significant cytotoxicity against B16 cells in vitro was consistently observed with lymphocytes prepared from B16 I-RNA treated animals, whereas lymphocytes from control animals or those treated with RNase-degraded B16 I-RNA or 3LL I-RNA had no effect. Results suggest that the combination of surgery and immunotherapy with I-RNA may be useful in preventing tumor recurrence in certain patients with cancer.

Prevention of death from metastases by immune RNA therapy

The effect of immune RNA treatment on the incidence of death from pulmonary metastases was studied in C57BL/6J mice after excision of a B16 murine melanoma. Immune RNA was extracted from the lymphoid tissues of guinea pigs immunized with B16 tumor and then incubated in vitro with normal C57BL/6J mouse splenocytes. Mice receiving intraperitoneal injections of these RNA-treated syngeneic splenocytes after the primary B16 isograft was resectioned showed significantly improved long-term survival (42 to 67 percent in three successive experiments) as compared to control mice (0 to 20 percent survival) receiving untreated splenocytes. The effect of RNA treatment was tumor-specific and ribonuclease sensitive. The results suggest that immunotherapy with immune RNA may be of benefit to certain patients after surgery for cancer.

Ribonucleic acid in the immune response

In the studies of experimental salmonellosis, immunization of mice with a live vaccine SER of S. enteritidis was found to be effective against further infection with virulent S. enteritidis 116--54. Macrophages obtained from the peritoneal cavity, subcutaneous tissue or liver of immunized mice inhibited intracellular growth of bacteria and resisted cell degeneration caused by engulfment of virulent 116--54 bacteria. This immunity was called cellular immunity. We discovered by chance in 1961 a transfer agent of immunity (TA) from the culture fluid of immunized macrophages. This agent is RNA in nature and can be extracted from the spleen, peritoneal exudate cells or the lymph node of immunized animals and is called immune (i) RNA. We could demonstrate antibody activity in macrophages treated in vitro or in vivo with iRNA by the immune adherence hemagglutination technique. Cellulr immunity against tumor cells could be transferred in vitro or in vivo to lymphocytes through iRNA prepared from the spleen cells of syngeneic, allogeneic and xenogeneic animals immunized with the tumor cells. We prepared iRNA against antigens capable of inducing humoral antibody production in animals, i.e., RBCs, bacterial toxin, bacterial flagella and hapten-protein conjugates. Serum antibody was not demonstrated in recipient animals of iRNA's by single or repeated injections of these agents. However, in these animals an increase in the number of specific antibody-carrying cells was found as rosette-formers. It was found further that prior injection of iRNA could induce immunologic memory and produced a high titer of humoral antibody after a boosting stimulation with a small dose of the corresponding antigen. The required interval between the first iRNA and the second antigenic stimulation, and the minimal effective doses of iRNA and antigen are described. We studied the interaction of iRNA with either T- or B-cells and with both cells using adoptive transfer system, athymic nude mice and neonatally thymectomized (NT) mice. Immune rna's against T-dependent and T-independent antigens could not induce the proliferation of antibody-carrying cells in cyclophosphamide-treated (B-cell depleted) mice. But these agents could induce the proliferation of rosette-formers, implying that iRNA's can replace some role of T-cells even against T dependent antigens. B-cells can be directly activated by treatment with iRNA against both T-dependent and T-independnet antigens, and they differentiated into rosette-formers. Passive transfers of iRNA were successful in establishing immunity against infection with S. enteritidis, or immunity to Salmonella flagella, RBCs and hapten-protein conjugates. The ability of iRNA to confer a secondary response of antibody formation is serially and passively transmissible in recipient animals. These facts suggest the presence of some mechanism that is responsible for the amplification of antigenic stimulation in the immune response...

Determinant selection and macrophage function in genetic control of the immune response

The immune response to insulin, in both mouse and guinea pig, is under control of H-linked immune response genes. When immunized with either pork or beef insulin in CFA, both strain 2 and 13 guinea pigs respond by antigen-specific lymphocyte proliferation and synthesis of specific antibody. The specificities of the elicited antibodies and indistinguishable between these inbred strains. By constrast, strain 2 T cells recognized a distinct region of the A chain alpha loop consisting of amino acid residues 8, 9 and 10, while strain 13 T cells see an as yet undefined region of the B chain. H2b (A chain alpha loop responder) and H2d (B chain responder) mice similarly discriminate which areas of the molecule are recognized by their T lymphocytes. The function of the Ir gene in both the guinea pig and mouse appears to be an intramolecular selection of discrete regions within the antigen for recognition by the T cell. The data presented suggest that this function operates at the level of the macrophage.

The regulation of lymphocyte functions by the macrophage

Macrophages may exert a regulatory influence at various stages in the life of the lymphocyte - they may influence the non-antigen-driven differentiation of lymphocytes - as exemplified by the effects on thymic differentiation; they may establish the mode and form of antigen to be presented or recognized by the lymphocyte; may regulate the lymphocyte's antigen-driven functions. Each of these critical regulatory steps needs explaining in molecular terms and integrated and placed in the context of the other regulatory functions of lymphocytes. The control of secretion of MP is an eloquent example of the molecular complexities and the intricate congrol mechanisms - internal and external - operating at each step of each regulatory process. A final comment concern the question of macrophage heterogeneity. Is the same cell performing all the functions of degradation, presentation, and secretion - or cytotoxicity? Or do we have subpopulation, each with a different role? This issue is not settled. The unitarians argue that the phagocytes pass through different stages of differentiation and that each function may become more or less prominent at each stage. Certainly, the manner in which each macrophage function is assayed can condition the outcome: for antigen presentation, one adds 1 % of macrophages to cultures of spleen cells; for cytotoxic assays, the figure is 50 to 100 macrophages per tumor cell! It is our feeling that until such time as membrane molecules are identified and used as probes for differentiation or for identification of subsets we will not resolve this issue. Along these lines, macrophages have been found to have Ia antigens (Hämmerling et al. 1975, Schwartz et al. 1976) and can be divided into two sets on the basis of the presence or absence of Ia. Dorf and I have found - by cytotoxicity - that only about 35 to 50% of peritoneal macrophages bear Ia molecules (Dorf & Uanue 1977). Exceptionally, some exudates will bear up to 75% positive cells. Neither Ia-positive nor Ia-negative macrophages change significantly after prolonged periods of culture. Whether these results indicate two defined subsets of macrophages is now being investigated.

Detection and localization of aleutian disease virus and its antigens in vivo by immunoferritin technique

Tissues from mink infected with aleutian disease virus were examined by the electron microscope for the presence of virus particles. Virus-like particles, measuring 22 nm in diameter, were observed in macrophages of spleen, mesenteric lymph node and in Kupffer cells in liver of mink ten to 13 days after infection. The virus-like particles were usually present in vacuoles inside the cytoplasm of macrophages and Kupffer cells and, occasionally, similar particles were observed inside the nucleus. Cells from uninfected mink did not contain such patricles. To correlate the existence of these virus-like particles with the presence of aleutian disease virus antigen in infected cells, tissues were processed for immunoferritin technique. It was found that aleutian disease virus antigen was present in vacuoles inside the cytoplasm of cells from the infected spleen, lymph node and liver, and that the location was similar to that of the 22 nm virus-like particles. In addition, some viral antigen was also detected as cytoplasmic granular material. The nuclei of some cells also contained aleutian disease virus antigen. The pattern of aleutian disease virus antigen was similar to the distribution of virus-like particles in cells of infected tissue. It is suggested that virus replication occurs inside the nucleus with subsequent accumulation of virus in the vacuoles of the cytoplasm.