Role of interleukin 1 in anti-immunoglobulin-induced B cell proliferation

In this report we describe conditions for polyclonal activation of small numbers of highly purified mouse B lymphocytes. Three signals are required for induction of DNA synthesis by the particular subset of small B lymphocytes investigated: a signal delivered by antibodies specific for the IgM receptor expressed on the B cell membrane; a signal delivered by a T cell-derived factor (B cell growth factor [BCGF]); and a signal delivered by the macrophage-derived factor interleukin 1 (IL-1). The conclusion that IL-1 has B cell co-stimulator activity is based on the findings that highly purified preparations of mouse and human IL-1 have the capacity to cause proliferation in B cells treated with anti-IgM and BCGF. Such cultures show an absolute dependence on exogenously added IL-1 when 2-mercaptoethanol is omitted from the medium. BCGF and IL-1 each act in a non-antigen-specific, non-H-2-restricted, synergistic manner. Their requirement is not observed when B cells are cultured at high density, presumably reflecting accessory cell contamination and endogenous factor production under these conditions. The B cell activation induced by these three signals is restricted to proliferation without the production of antibody-forming cells.

Soluble factors involved in B cell differentiation: identification of two distinct T cell-replacing factors (TRF)

Highly purified B lymphocytes cultured with affinity-purified goat anti-mouse IgM antibodies and B cell growth factor (BCGF) proliferate but fail to differentiate into immunoglobulin-synthesizing cells during 4-day cultures. Induction of immunoglobulin (Ig) synthesis depends on the presence of two additional T cell-derived factors (T cell-replacing factors [TRF]). One TRF, designated B15 1K 12-TRF, is found in the supernatant of B15 1K 12 T hybridoma cells. It is required relatively early in these cultures and appears to cause an increase in cell yield as well as Ig synthesis. The second factor, designated EL-TRF, is found in PMA-induced EL-4 supernatant. It appears to be different from both BCGF and IL 2 in that it can be separated from the former by isoelectric focusing and from the latter by phenyl-Sepharose chromatography. EL-TRF is still active if added on the last day of a 4-day culture. A model for the action of anti-IgM and these three T cell-derived factors in B cell activation and differentiation is proposed.

Soluble factors involved in B cell differentiation: identification of two distinct T cell-replacing factors (TRF)

Highly purified B lymphocytes cultured with affinity-purified goat anti-mouse IgM antibodies and B cell growth factor (BCGF) proliferate but fail to differentiate into immunoglobulin-synthesizing cells during 4-day cultures. Induction of immunoglobulin (Ig) synthesis depends on the presence of two additional T cell-derived factors (T cell-replacing factors [TRF]). One TRF, designated B15 1K 12-TRF, is found in the supernatant of B15 1K 12 T hybridoma cells. It is required relatively early in these cultures and appears to cause an increase in cell yield as well as Ig synthesis. The second factor, designated EL-TRF, is found in PMA-induced EL-4 supernatant. It appears to be different from both BCGF and IL 2 in that it can be separated from the former by isoelectric focusing and from the latter by phenyl-Sepharose chromatography. EL-TRF is still active if added on the last day of a 4-day culture. A model for the action of anti-IgM and these three T cell-derived factors in B cell activation and differentiation is proposed.

Regulation of B-cell growth and differentiation by soluble factors

The B-lymphocyte family of cells presents one of the most remarkable opportunities for the detailed study of regulation of growth and differentiation. Some members of this cell population have the property that they may be stimulated by ligand-receptor interactions, together with the sequential action of a series of lymphokines, to progress from the resting state, through several rounds of proliferation, and then to differentiate to immunoglobulin secretion. Other cells in this group participate in cognate cellular interactions with helper T cells in which the recognition of both antigen and a class II MHC molecule on the B-cell surface is key to activation. The differentiation of these cells is also controlled by soluble products. We have reviewed our developing knowledge of the biochemistry and mode of action of the lymphokines that act upon B cells. These include distinct growth and differentiation factors. Among these are the BCGFs of mice and humans and the various TRFs, which include molecules often described as differentiation factors. The next several years should witness major progress in understanding the physicochemical properties of the B cell-specific factors, their time and nature of action, and the nature of their receptors. In addition, we can anticipate a major effort to understand the intracellular events that flow from the action of specific growth and differentiation factors that act upon B cells. Such information should lead to a new physiologically-based pharmacology for manipulation of antibody responses in human disease and in responses to vaccines. In addition, the fuller understanding of the nature and mode of action of the various growth and differentiation factors should make long-term growth of cloned B cells a procedure that can be routinely used in immunological laboratories for the precise study of the biology of responses by homogeneous populations of B lymphocytes.

Identification of a T cell-derived b cell growth factor distinct from interleukin 2

We report here a factor (B cell growth factor) found in induced supernatants of the mouse thymoma EL4 that co-stimulates with anti-IgM antibodies in short-term cultures of purified B lymphocytes to induce polyclonal B cell proliferation but not antibody-forming cell production. The factor is not mitogenic for resting B cells and interacts with anti-IgM-activated B cells in a non-H-2-restricted manner. Absorption studies and molecular weight analysis reveal the factor is distinct from interleukin 2. This factor synergises with antigen, interleukin 2, and an interleukin 2-free, B cell growth factor-free T cell supernatant that contains T cell-replacing factor to produce erythrocyte-specific plaque-forming cells in cultures of highly purified B cells.

Long-term culture of normal mouse B lymphocytes

A procedure is described for the preparation of long-term lines of normal mouse B lymphocytes. Surface immunoglobulin-bearing splenic B lymphocytes were purified with the fluorescence-activated cell sorter and then cultured with lipopolysaccharide for 1-4 wk. The cells were then transferred into medium supplemented with a T-hybridoma-derived supernatant containing interleukin 2 (IL2). Continuous feeding with this supernatant led to the establishment of cell lines that also could be propagated to IL 2-free medium containing interleukin 1 but not in culture medium alone. Cell lines have been propagated in this manner for as long as 10 mo. The cells in these lines have the appearance for small, dense lymphocytes, which all bear surface IgM detectable by immunofluorescence, rosetting, and surface radiolabeling and immunoprecipitation. The cells express Ia and lack Thy 1. These cultured B lymphocytes are unresponsive to lipopolysaccharide but can be activated to become more rapidly dividing, immunoglobulin-secreting cells by exposure to culture supernatants containing both T-cell-replacing factor and IL 2.

Glucocorticoid-induced elevations of C1-esterase inhibitor: a mechanism for protection against lethal dose range contrast challenge in rabbits

Rabbits pretreated with methylprednisolone acquired significant protection against an intravenous challenge of meglumine iodipamide. In comparison to controls, the pretreated rabbits showed moderate elevations of Factor XII, and rather striking elevations of C1-esterase inhibitor. Treated rabbits also showed significantly less granulocytosis. It is believed that the protective effect can be ascribed to the modulation of acute phase reactants by increased concentrations of C1-esterase inhibitor.

Activation systems in contrast idiosyncrasy

Both animal and human data suggest the possibility that the C1 esterase inhibitor may play an important controlling role in contrast media systemic reactions. This critical controlling protein has a major inhibitory effect on C1, kallikrein, activated factor XII of the intrinsic coagulation system, and on plasmin. In addition, it probably has other inhibitory effects not so well documented. Any circumstance that contributes to a continuing activation of the complement, coagulation, kinin, or fibrinolytic systems may result in partial consumption of the inhibitor and predispose the individual to adverse reactions to contrast challenge.

Analgesic nephropathy induced by common proprietary mixtures

Renal papillary necrosis has been induced in 36.4% to 75% of rats which were gavage-fed with analgesic mixtures containing proprietary combinations of aspirin, paracetamol, phenacetin, phenazone, salicylamide and caffeine. These findings support the recent recommendations of the National Health and Medical Research Council which suggest that the free availability of analgesic mixtures be restricted.

Towards an interactive high visual complexity animation system

A computer animation system is discussed which employs interactive techniques and presents a unified approach to the graphical display of complex three dimensional data. The system facilitates the generation, manipulation and display of highly detailed data with the aid of interactive devices and a video interface to a standard color TV monitor. The system enables the animator to create a variety of objects (including texture) and to specify the necessary transformations for animation sequences. A run length processing technique combined with a brute force Z-buffer algorithm has been newly designed and implemented that can handle the intersection of several million faces, lines and points. This makes possible a full range of visual cues to simulate fire, smoke, water and complex 3-D texture such as grass, hair and bark. Basic concepts and approaches are described. The display algorithm and the procedure model to generate texture are presented and the implications of the system for computer animation are discussed. Extensions to the system are outlined which include a unique graphics display processor currently under construction that includes a partial implementation of the display algorithm in hardware.

Some limits to post-antigen generation of diversity: failure to detect variants in clones of hapten-specific antibody-forming cells (AFC) developing in culture from direct AFC-progenitor B cells

A search was made for variants in clones of hapten-specific antibody-forming cells (AFC) arising by stimulation of mature B cells with either thymus-independent hapten-POL (polymerized bacterial flagellin) conjugates, or the polyclonal activator lipopolysaccharides. Enriched, hapten-binding B cells or unfractionated spleen cells were cultivated for 3-4 days at limiting dilution in the presence of thymus filler cells, and the AFC in each microculture well were then assayed for plaque formation on various hapten-sheep red cell monolayers. No variants were found from (4-hydroxy-3-iodo-5-nitrophenyl) acetyl (NIP) to 2,4-dinitrophenyl specificity, nor from fluorescein (FLU) to NIP specificity. No variants were found in avidity for FLU hapten. All 374 clones examined, including clones of up to 300 AFC, appeared to be homogeneous in antibody specificity and plaque morphology under our conditions. These results differ from published findings using erythrocytes as antigens. Reasons for this discrepancy are discussed, including differences in sensitivity differences in immunological similarity between the test antigens, and in the particular B cell subsets involved.

Antigen-Initiated B Lymphocyte Differentiation

Both primary IgM and secondary IgM and IgG adoptive immune responses to the thymus-independent antigen NIP-POL were found to proceed in two stages. The first 3 to 4 days of these responses required a stimulus, but this could be provided by an unrelated antigen such as HRC. Only the second 3- to 4-day stage of the response, leading to an AFC peak at day 8, required the specific antigen NIP-POL. This novel priming schedule of nonspecific followed by specific antigenic stimulation in fact produced a significantly greater AFC response than the standard specific immunization procedure. With the schedule of nonspecific, then specific antigen injection, the primary IgM response was T cell independent. Two sequential injections of specific antigen also gave an elevated adoptive response from the same B cell subset, but this time the increased component of the response was T cell dependent.

The results corroborate earlier work, and support a model of two sequentially related and “antigen”-responsive subsets of both primary and secondary B cells, termed “pre-progenitors” and “direct AFC progenitors”. Responses to antigens are thus two-tiered. In the first stage, all “pre-progenitor” subsets are nonspecifically activated to proliferate and differentiate into “direct-progenitor” B cells. This stage is different from “pre-B” to B cell development. Although it may occur continuously at a lower level in normal animals, it requires an environmental or experimentally introduced stimulus, and is probably triggered via macrophage activation. In the second stage the conventional rules apply, and antigens specifically stimulate antigen-restricted clones of direct-progenitor B cells to produce AFC.

Bleeding vascular malformations of the intestine

Thirty-nine patients with bleeding vascular malformations were evaluated. The age range was from 3 to 78 years, with a bimodal age distribution. The younger patients had no associated diseases, while those in the older category invariably had an associated cardiac lesion (aortic stenosis in 12 patients and severe atherosclerotic disease in 11 patients). With experience, colonoscopy has become a valuable adjunct to arteriography with the lesion visualized in 12 patients. Arteriography is the most useful study being diagnostic in 35 of 38 cases. Exploration alone was diagnostic in only one of 39 patients. The most common site of bleeding was the cecum (21 patients) followed by the proximal small intestine (eight patients), terminal ileum (seven patients), and ascending colon (five patients). The lesions in the proximal small bowel were much more common in the younger patients and were believed to be congenital. Resection controlled the bleeding in the majority of patients, although four recurrences have been noted. All have been documented angiographically to have been from a new lesion and two were controlled with reoperation. The key elements to control of these patient's bleeding include: (1) systematic work-up with a team approach emphasizing careful visceral angiography, and (2) the avoidance of a premature laparotomy prior to complete evaluation.