/pdf/secretory-products-of-macrophages-5cf7rlxshh.pdf

Secretory products of macrophages.

Interleukin-2 (IL-2), the first of a series of lymphocytotrophic hormones to be recognized and completely characterized, is pivotal for the generation and regulation of the immune response. A T lymphocyte product, IL-2 also stimulates T cells to undergo cell cycle progression via a finite number of interactions with its specific membrane receptors. Because T cell clonal proliferation after antigen challenge is obligatory for immune responsiveness and immune memory, the IL-2-T cell system has opened the way to a molecular understanding of phenomena that are fundamental to biology, immunology, and medicine.

https://science.sciencemag.org/content/sci/240/4856/1169.full.pdf

Interleukin-2: inception, impact, and implications.

Inflammation, the most ancient aspect of the host immune response, is surely of great value to the host, insofar as agents that suppress inflam­ mation in a nonspecific fashion predispose to infection. Yet, the inflam­ matory response to invasive organisms may also, if sufficiently intense or inappropriately prolonged, cause injury or death. A delicate balance has thus been achieved, one which clinicians strive to maintain through judicious application of anti-inflammatory medications (e.g. glucocorti­ coids, nonsteroidal anti-inflammatory agents, and cytotoxic drugs). Only recently have we come to understand that many aspects of this primitive response to host invasion are governed by polypeptide hormones, in turn produced by immune effector cells. Moreover, we have come to appreciate the pleiotropic properties of these so-called "cytokines." It would appear that a ' limited number of cytokines are capable of orches­ trating disease states that scarcely resemble one another; among them, endotoxic shock, graft-vs-host disease, cerebral malaria, and cancer cachexia. Cells of monocyte/macrophage lineage play a central role in cytokine ("mono kine") production and so act to modulate many aspects of the inflammatory response. While devoid of specificity and immunologic mem-

The biology of cachectin/TNF--a primary mediator of the host response

Heritable disorders of connective tissue

Cyclophilin, a specific cytosolic binding protein responsible for the concentration of the immunosuppressant cyclosporin A by lymphoid cells, was purified to homogeneity from bovine thymocytes. Cation-exchange high-performance liquid chromatography resolved a major and minor cyclophilin species that bind cyclosporin A with a dissociation constant of about 2 X 10(-7) moles per liter and specific activities of 77 and 67 micrograms per milligram of protein, respectively. Both cyclophilin species have an apparent molecular weight of 15,000, an isoelectric point of 9.6, and nearly identical amino acid compositions. A portion of the NH2-terminal amino acid sequence of the major species was determined. The cyclosporin A-binding activity of cyclophilin is sulfhydryl dependent, unstable at 56 degrees C and at pH 4 or 9.5, and sensitive to trypsin but not to chymotrypsin digestion. Cyclophilin specifically binds a series of cyclosporin analogs in proportion to their activity in a mixed lymphocyte reaction. Isolation of cyclophilin from the cytosol of thymocytes suggests that the immunosuppressive activity of cyclosporin A is mediated by an intracellular mechanism, not by a membrane-associated mechanism.

https://science.sciencemag.org/content/sci/226/4674/544.full.pdf

Cyclophilin: A Specific Cytosolic Binding Protein for Cyclosporin A

Human and mouse lymphoid cells, stimulated by phytohemagglutinin (PHA) or lipopolysaccharide W (LPS), release supernatant factor(s) which are mitogenic for mouse thymocytes and which potentiate their responses to PHA or concanavalin A (Con A), The term LAF (lymphocyte-activating factor) is proposed for this activity. LAF not only enhances the mitotic responses of the less dense thymus subpopulations (A, B, and C) separable on discontinuous bovine serum albumin (BSA) gradients but also gives substantial responses in the otherwise inert cells of the denser fractions D and P. LAF does not exert a potentiating stimulatory effect on the responses of unfractionated mouse spleen cells, but does act synergistically with PHA on nonadherent spleen cells and on spleen cells of mice of several strains 5 days after irradiation and injection of thymocytes. Similarly LAF, which has no visible effect on unfractionated human peripheral blood cells, strongly potentiates the PHA response of column-purified lymphocytes, when these are cultured at low concentration. We conclude that LAF stimulates both central and peripheral T lymphocytes and enhances their responses to other stimulants.

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Potentiation of the t-lymphocyte response to mitogens : i. the responding cell

Effective supernatants (SUP), which potentiate mouse T-cell responses to phytohemagglutin (PHA), are obtained from cells of several species (human, rabbit, rat, mouse) and indeed from syngeneic spleen, thymus, or bone marrow cells. Unstimulated cells release some SUP activity but more is produced after stimulation. Lipopolysaccharide (LPS) produced very active SUP in all cultures tested. PHA was similarly active on human leukocytes only, whereas concanavalin A (Con A) gave highly efficient SUP only with mouse spleen cells. SUP production is not correlated with a mitotic response of the donor cells and is observed in cultures unable to respond mitotically to the stimulant. Adherent mouse spleen cell populations, consisting largely or entirely of macrophages, produce active SUP, while nonadherent cells do not. Similarly, purification of human peripheral leukocytes on nylon columns, with removal of macrophages and other adherent cells, destroys their ability to produce SUP. The importance of indirect effects in stimulating mitotic responses of T cells is emphasized by the fact that the mitotic response of mouse thymocytes to LPS and its ability to potentiate the response of these cells to PHA disappears with removal of adherent cells from the thymocyte population. Conversely the production of SUP from spleen cells stimulated by Con A requires the presence of T cells.

https://rupress.org/jem/article-pdf/136/1/143/1084773/143.pdf

Potentiation of the t-lymphocyte response to mitogens ii. the cellular source of potentiating mediator(s)

The cytopathic effect of lymph node cells from tuberculin-sensitized rats on rat embryo fibroblasts in the presence of PPD was not enhanced by admixture of normal (nonsensitized) lymph node cells. Preincubation studies showed that this in vitro response is initiated by the reaction of lymphocytes with specific antigen, beginning within 30 min, rather than uptake of antigen by the fibroblasts. The supernatant fluids from suspensions of sensitized cells incubated with PPD for 17 hr or more possessed cytotoxic activity. The target fibroblasts showed a marked increase in acid phosphatase content within 48 hr after the addition of sensitized lymph node cells and antigen.

/pdf/cytotoxicity-mediated-by-soluble-antigen-and-lymphocytes-in-5d1mz099os.pdf

Cytotoxicity mediated by soluble antigen and lymphocytes in delayed hypersensitivity : iii. analysis of mechanism

In the presence of specific antigen, lymph node cells from inbred rats with delayed hypersensitivity to tuberculoprotein, bovine gammaglobulin, and egg albumin produced progressive destruction of monolayers of rat embryo fibroblasts in tissue culture, first apparent at 48 hr and maximal at 72 hr. The effect was specific and did not depend on a genetic difference between the lymph node cells and target cells. It required antigen concentrations equal to or greater than 1.25 µg/ml and lymphocyte: target cell ratios of approximately 10 or 20:1. It could be evaluated both by a plaquing technique and by cell enumeration with an electronic particle counter.

https://rupress.org/jem/article-pdf/128/6/1237/1392257/1237.pdf

Byron H. Waksman

Papers

Potentiation of the t-lymphocyte response to mitogens : i. the responding cell

Potentiation of the t-lymphocyte response to mitogens ii. the cellular source of potentiating mediator(s)

Cytotoxicity mediated by soluble antigen and lymphocytes in delayed hypersensitivity : iii. analysis of mechanism

Cytotoxicity mediated by soluble antigen and lymphocytes in delayed hypersensitivity. I. Characterization of the phenomenon.

On soluble mediators of immunologic regulation