Cells involved in cell-mediated and transplantation immunity. II. A consideration of the functional identity of the cells involved in both humoral and cell-mediated immunity: a phylogenetic approach

The literature concerned with the types of cells that participate in the humoral and cell-mediated immune response has been reviewed. It is postulated that the initial cells that are involved in mediating both types of immunity are functionally identical in that both are antigen-reactive cells. In the case of the humoral immune response, the interaction of the antigen-reactive cells with the antigen leads to the release or transfer of "information" to the antibody-forming cell, resulting in the synthesis and secretion of antibody molecules. In the case of cell-mediated immunity, it is considered that the primitive antigen-reactive cell itself transforms into the sensitized cell which infiltrates the site of antigen administration.

The secondary antibody response in tissue culture. IV. Studies of the in vivo and in vitro antigenicity of native, aggregate-free and aggregated human gamma globulin in rabbits

The antigenicity of native, aggregate-free and heat-aggregated HGG was investigated in vivo and in vitro, using the cell culture and fragment culture systems. Although the aggregate-free material displayed very low immunogenicity in vivo, its antigenicity was markedly enhanced if injected along with Freund's adjuvant. Results of cell culture experiments, using immune spleen cells, paralleled the in vivo results in that the aggregated HGG was highly blastogenic whereas the aggregate-free HGG could not induce blastogenesis of the immune cells. Results of an opposite nature derived from the fragment culture experiments in that aggregate-free HGG could readily induce a secondary immune response in vitro whereas the aggregated HGG was unable to do so. The significance of these results is discussed.

The inhibition of trypsin, plasmin, and thrombin by benzyl 4-guanidinobenzoate and 4'-nitrobenzyl 4-guanidinobenzoate

The inhibition of the enzymes trypsin, plasmin, and thrombin by benzyl 4-guanidinobenzoate and 4'-nitrobenzyl 4-guanidinobenzoate is caused by acylation of the active site. Second order rate constants were determined.

Cells involved in cell-mediated and transplantation immunity in the rabbit. I. The noninvolvement of the bone marrow antigen reactive cell in the transplant rejection reaction

Rabbits were subjected to 800 r total body irradiation to render them immunoincopetent with respect to the humoral immune response. These rabbits were, however, only slightly less capable of rejecting skin allografts than nonirradiated rabbits. Furthermore, the administration of normal or specifically "primed" bone marrow cells (bone marrow obtained from a rabbit injected one to two days previously with the spleen cells obtained from the prospective skin donor) did not enhance or inhibit the graft rejection reaction. It is concluded that the cells mediating the humoral immune response are different from those mediating the cellular immune response.

Cells involved in the immune response. XVI. The response of immune rabbit cells to phytohemagglutinin, antigen, and goat anti-rabbit immunoglobulin antiserum

There exists in the rabbit a population of lymphocytes carrying immunoglobulin-like receptors on their surface. These receptors interact with antigen and with anti-immunoglobulin antibodies and appear to mediate the recognition process leading to the humoral immune response. There exists in the rabbit a second population of lymphocytes capable of reacting with phytohemagglutinin. This population of lymphocytes is different from the one capable of reacting with soluble protein antigens or anti-immunoglobulin antiserum and is probably involved in the mediation of cellular immunity.

Cells involved in the immune response. XII. The differing responses of normal rabbit lymphoid cells to phytohemagglutinin, goat anti-rabbit immunoglobulin antiserum and allogeneic and xenogeneic lymphocytes

Cells of the different lymphoid organs in the normal adult rabbit were investigated for their capacity to respond in vitro to a number of stimuli, such as phytohemagglutinin (PHA), anti-rabbit immunoglobulin antiserum (GARIG) and allogeneic and xenogeneic lymphoid cells, and for their capacity to adsorb radioactively-labeled anti-immunoglobulin antiserum. The bone marrow cells responded minimally to PHA, GARIG, and the allogeneic and xenogeneic stimuli. The thymus cells were unable to respond to stimulation with GARIG although they responded to the other stimuli. The cells of the other lymphoid organs tested responded to all the mitogenic agents, to varying degrees. On the basis of the results presented and the findings of other investigators, it is concluded that: 1. The response of the cells to GARIG indicates a potential capacity to mediate humoral immunity and requires the presence of immunoglobulin or immunoglobulin-like recognition sites on the cell surface. 2. The response of the cells to PHA and allogeneic and xenogeneic cells indicates a potential capacity to mediate cellular immunity and does not necessitate the presence of immunoglobulin-recognition sites on the cell surface. 3. The thymus in the normal adult rabbit consists of cells capable of mediating cellular immunity only. 4. The other lymphoid organs appear to possess cells capable of mediating humoral and cellular immunity.

Cells involved in the immune response. 8. The relationship between the loss and reappearance of antigen-reactive cells and immune responsiveness after irradiation of normal adult rabbits

By appropriate irradiation and cell transfer experiments, a direct correlation was observed between the presence of viable and immunologically active antigen-reactive cells and the capacity of the rabbits to respond following immunization. Rabbits given 800 R total body irradiation were unable to elicit a humoral immune response nor did they possess significant numbers of antigen-reactive cells. The ability to respond with humoral antibody formation did not reappear until antigen-reactive cells could be detected. These results strongly indicate that the presence of competent antigen-reactive cells are necessary for the successful induction of the humoral immune response in the rabbit.

Cells involved in the immune response. 13. The nature of the cellular interactions relating antibody formation and immunologic tolerance: a unified hypothesis

The various cells and cell pathways involved in the induction of the primary humoral immune response have been discussed from the point of view of the unitary, as opposed to the multiple, pathway concept. The immunocompetent cells made unresponsive in the immunologically tolerant animal and the cells capable of responding with antibody formation were considered. It is concluded that there exist multiple cellular pathways through which the humoral immune response may be expressed.

Cells involved in the immune response, IX. Depletion from the normal rabbit bone marrow of antigen-reactive cells directed toward human peripheral leukocytes

Normal adult rabbits were injected intravenously with peripheral leukocytes obtained from a normal human volunteer (donor A). The animals were sacrificed 24 hours later, and their bone marrow cells (primed bone marrow) or bone marrow cells obtained from a normal, unimmunized rabbit (normal bone marrow) were injected intravenously into irradiated (800 r) rabbits. The latter were immunized with peripheral leukocytes of donor A. The antisera obtained from the irradiated rabbits given primed bone marrow cells displayed minimal or no cytotoxic activity toward white cells of either donor A or an unrelated donor B. On the other hand, antisera obtained from irradiated rabbits given normal bone marrow cells displayed high titers of cytotoxic activity with respect to donor A cells only. It is concluded that rabbit bone marrow can be depleted of antigen-reactive cells directed toward white cell antigens following injection of the white cells intravenously and that these bone marrow cells are incapable of conferring antibody-forming capacity, in irradiated recipients, directed to this particular species of white cells. The relevance of these findings to the field of transplantation in general is discussed.

Cells involved in the immune response. XI. Identification of the antigen-reactive cell as the tolerant cell in the immunologically tolerant rabbit

Rabbits were made immunologically tolerant to either human serum albumin or bovine gamma globulin by the neonatal administration of antigen. At 10 wk of age, they were challenged with the tolerogenic antigen and found to be non-responsive. However, these tolerant rabbits could respond with humoral antibody formation directed toward the tolerogenic antigen if they were treated with normal, allogeneic bone marrow or bone marrow obtained from a rabbit made tolerant toward a different antigen. They were incapable of responding if they were given bone marrow obtained from a rabbit previously made tolerant to the tolerogenic antigen. Irradiated rabbits were unable to respond if treated with tolerant bone marrow, but could respond well if given normal bone marrow. Since it has previously been demonstrated that the antibody-forming cell, in an irradiated recipient of allogeneic bone marrow, is of recipient and not donor origin, the data presented strongly indicate that the unresponsive cell in the immunologically tolerant rabbit is the antigen-reactive cell.

Cells involved in the immune response. X. The transfer of antibody-forming capacity to irradiated rabbits by antigen-reactive cells isolated from normal allogeneic rabbit bone marrow after passage through antigen-sensitized glass bead columns

The antigen-reactive cells in normal rabbit bone marrow could be isolated from a suspension of marrow cells by passage of the cells through an antigen-sensitized glass bead column. The cells which passed through the column were deficient in antigen-reactive cells directed to the antigen used to sensitize the glass beads, whereas the cells eluted from the column could transfer antibody-forming capacity to irradiated recipients only with respect to the specific sensitizing antigen. Separation of the bone marrow antigen-reactive cells could not be achieved by passage of the cells through nonsensitized glass bead columns or in the presence of excess free antigen in the column. Cells which were retained by, and later eluted from, the antigen-sensitized glass bead columns were mostly small mononuclear cells, whereas cells which passed through the columns were morphologically similar to the original unfractionated bone marrow cell suspension. The data indicate the presence of an antibody or antibody-like structure, with defined immunological specificity, on the surface of the normal bone marrow antigen-reactive cell.

Cells involved in the immune response. VII. The demonstration, using allotypic markers, of antibody formation by irradiation-resistant cells of irradiated rabbits injected with normal allogeneic bone marrow cells and sheep erythrocytes

Bone marrow cells obtained from rabbits of one allotype were injected into irradiated rabbits of a different allotype. The recipients were also injected with sheep red blood cells, and their spleen cells were tested for plaque-forming capacity 7 days later. Spleen cells of all recipients gave large numbers of plaques as did spleen cells incubated with antiserum, directed toward donor allotype. However, incubation of the recipient spleen cells with antiserum directed toward recipient allotype completely suppressed plaque formation. These results demonstrate that antibody-formation in irradiated recipients of transferred lymphoid cells is a property of the recipient animal and that the antibody-forming cell is relatively irradiation-resistant. It was also demonstrated that only viable normal bone marrow cells are capable of transferring antibody-forming capacity to irradiated recipient rabbits. Neither sonicates nor heat-killed preparations of normal rabbit bone marrow cells possessed this capacity.

Cells involved in the immune response. VI. The immune response to red blood cells in irradiated rabbits after administration of normal, primed, or immune allogeneic rabbit bone marrow cells

Irradiated rabbits given allogeneic bone marrow cells from normal adult donors responded to an injection of sheep red blood cells by forming circulating antibodies. Their spleen cells were also capable of forming many plaques using the hemolysis in gel technique, and were also capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine upon exposure to the specific antigen in vitro. However, irradiated rabbits injected with allogeneic bone marrow obtained from rabbits injected with sheep red blood cells 24 hr prior to sacrifice (primed donors) were incapable of mounting an immune response after stimulation with sheep red cells. This loss of reactivity by the bone marrow from primed donors is specific for the antigen injected, since the immune response of the irradiated recipients to a non-cross-reacting antigen, the horse red blood cell, is unimpaired. Treatment of the bone marrow donors with high-titered specific antiserum to sheep red cells for 24 hr prior to sacrifice did not result in any diminished ability of their bone marrow cells to transfer antibody-forming capacity to sheep red blood cells. The significance of these results, with respect to the origin of the antigen-reactive and antibody-forming cells in the rabbit, is discussed.

The response of leucocytes of agammaglobulinaemia subjects to phythohaemagglutinin and anti-immunoglobulin antiserum

Leucocytes of three patients with congenital (case 1) or acquired (cases 2 and 3) agammaglobulinaemia were studied in vitro in cell culture for their capacity to undergo blastogenesis and mitosis upon exposure to phytohaemagglutinin (PHA) or anti-immunoglobulin sera. Synthesis of DNA was measured by the incorporation of tritiated thymidine added 16 hr before termination of culture. The lymphocytes of patients Nos. 2 and 3 showed little or no uptake of the labelled thymidine following stimulation by antisera, whereas those of patient No. 1 were at the upper limit of normal. Response to stimulation by PHA was within the normal range for patients Nos. 1 and 3 but subnormal for patient No. 2. The different responses to PHA and anti-immunoglobulin antisera suggest basic heterogeneity of the defects in the lymphocytes of these patients.

There was lack of correlation between delayed type dermal reactivity and lymphocyte reactivity to PHA in patient No. 3.

Determination of Root Exudates in a Steril Continuous Flow Culture. II. Short-Term and Long-Term Variations of Exudation Intensity

The exudate production of alfalfa under the conditions of the sterile flow culture was quantitatively measured. In the first 40 days 3.10(-3) mumoles amino-N, 2.5 muequivalents of organic acids and approximately 10(-4) mumoles of reducing sugars were liberated per plant and per day into the percolating nutrient solution. The amino acid concentration in the outflow varies according to a daily periodicity. The exudation of a colored substance also shows daily periodical variations. This pattern is different from the pattern of the amino acid exudation, however, and directly coupled to shoot illumination. Short-term 2,4-dinitrophenol additions to the nutrient lower the liberation of amino acids into the percolating solution.

Determination of root exudates in a steril continuous flow culture. I. The culture method

A sterile plant culture consisting of culture vessels, culture solution container, collecting flasks for percolating nutrient solution, illumination and aeration systems and a suitable pump is described. Its difference with other culture methods is a very slow, continuous percolation of the nutrient solution through the rooting medium. Well defined and controllable conditions can thus be established in the rhizosphere over long culture periods. Samples can be collected at short intervals without disturbing the rhizosphere in any way nor endangering the sterility of the culture. One of the fundamental factors determining the special ecological characteristics of the plant rhizosphere is the liberation of organic and inorganic substances by the plant root. During the study of this phenomenon it became evident that the amount of substances liberated varies within wide limits (factors 100 to 1000) according to the conditions in which the root is developing.

Cells involved in the immune response. IV. The response of normal and immune rabbit bone marrow and lymphoid tissue lymphocytes to antigens in vitro

Cell suspensions of immune rabbit lymph nodes and spleen were capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine when maintained in culture with the specific antigen in vitro. They did not respond to other, non-cross-reacting antigens. The blastogenic response obtained with immune lymph node cells could be correlated with the antibody synthesizing capacity of fragment cultures prepared from the same lymph nodes. Cell suspensions of immune bone marrow responded to non-cross-reacting antigens only whereas cell suspensions of immune thymus, sacculus rotundus, and appendix did not respond when exposed to any of the antigens tested. On the other hand, neither fragments nor cell suspensions prepared from lymph nodes, spleen, and thymus of normal, unimmunized rabbits responded with antibody formation and blastogenesis when exposed to any of the antigens. However, normal bone marrow cells responded with marked blastogenesis and tritiated thymidine uptake. The specificity of this in vitro bone marrow response was demonstrated by the fact that the injection of a protein antigen in vivo resulted in the loss of reactivity by the marrow cell to that particular antigen but not to the other, non-cross-reacting antigens. Furthermore, bone marrow cells of tolerant rabbits failed to respond to the specific antigen in vitro. It was also demonstrated that normal bone marrow cells incubated with antigen are capable of forming antibody which could be detected by the fluorescent antibody technique. This response of the bone marrow cells has been localized to the lymphocyte-rich fraction of the bone marrow. It is concluded that the bone marrow lymphocyte, by virtue of its capacity to react with blastogenesis and mitosis and with antibody formation upon initial exposure to the antigen, a capacity not possessed by lymphocytes of the other lymphoid organs, has a preeminent role in the sequence of cellular events culminating in antibody formation.