Primary antibody response in organ cultures

Establishment and characterization of a cell line from the Chinese soft-shelled turtle Pelodiscus sinensis

The establishment and partial characterization of Pelodiscus sinensis continuous cell line is described here. A novel P. sinensis fibroblast cell line, designated PSF, was established from heart tissue by the semi-digestion explant culture technique. Since its initiation in July 2013, the cell line has been subcultured at 30°C in minimal essential medium (MEM) containing 15% (v/v) fetal bovine serum for more than 50 passages. The growth curve of the cell line revealed the population doubling time was 51.1 h. Karyotyping analysis indicated the modal chromosome number was 66, and no microbial contamination was detected. The PSF cell line produced significant fluorescent signals after transfection with plasmid pEGFP-C3. Analysis of mitochondrial cytochrome D-loop sequences revealed 96% identity among other Chinese turtle subspecies. Several cell line characterizations included morphological analysis and immunocytochemistry, which revealed the origin of the PSF cell line was fibroblast-like cells. Measurement of the isoenzymes lactic dehydrogenase and malic dehydrogenase showed no cross-contamination of this cell line with other species. This newly established cell line will be a valuable tool for transgenic and genetic manipulation studies and will act as an efficient instrument for studies of the viral diseases of the soft-shelled turtle.

Reactivation in vitro of immunocompetence in irradiated mouse spleen

The restoration of immunological competence to irradiated adult mouse spleen was studied using an in vitro assay system. Competence of the spleen to evoke a graft versus host reaction in vitro was lost upon sublethal irradiation (550 R). Regeneration of immune competence occurred when such spleens were grown for 2–3 days in the presence of thymus tissue, but not when grown in the presence of a variety of other tissues. This thymic activity was demonstrated to occur across an intervening Millipore filter barrier. When lethal doses of irradiation were used, reactivation of immune competence did not occur unless both thymus and bone marrow were present. In this experimental situation the bone marrow appeared to supply the immunocompetent cells.

Immunization and culture of rainbow trout organ sections in vitro

Splenic and anterior kidney sections or whole organs were excised from large (1 kg) or small (200 g) rainbow trout (Salmo gairdneri) and placed in sterile 60 mm plastic plates containing 10 ml of Eagle's minimal essential medium (EMEM) supplemented with normal or fetal calf serum for in vitro culture. The organ samples were immunized in vitro by direct injection or by mixing in the medium Yersinia ruckeri O-antigen or dinitrophenyl-Ficoll. The medium was changed once during the 10-day incubation at 15 C. The passive hemolytic plaque assay demonstrated antibody production from the plaque-forming cells (PFC); passive hemagglutination was used to measure antibody titers in the media. High numbers of PFC occurred in cultures of either kidney or spleen, demonstrating that these organs can function independently for antibody production. Splenic sections from large fish produced more PFC than comparable whole organs from small fish. EMEM supplemented with 2% normal calf serum was a satisfactory culture medium. 2-hydroxyethyl-mercaptan an ingredient used in mammalian cell culture, inhibited antibody production in trout cells. These techniques are being used in the culture of organs and cells to elucidate pathways and sequences of antigen uptake and delivery of the immunopoietic tissues in trout.

Preferential production of IgA antibodies by spleen fragments immunized and maintained in vitro

Primary immune responses were induced with a hapten conjugate of Ficol (NIP38-Ficoll) in cultures of mouse spleen fragments. The production of anti-NIP antibodies and mouse immunoglobulins IgA and IgG was monitored by solid-phase radioimmunoassays. Cultures produced IgA and IgG without any stimulation. IgA at a rate of c.60ng/mg of wet tissue per day throughout the 10-day culture period. Background production of IgG gradually declined from almost 1000 ng/mg/day at the beginning to 100 ng/mg/day at the end. Immunization modestly reduced the decline of the IgG production. It increased the production of IgA fourfold between days 6 and 8. It induced an antibody production that had its peak between days 6 and 8. Up to 50 ng of anti-NIP antibody was produced during this period per mg of wet tissue per day. Of this antibody 75-90% was IgA. When the same antigen was injected into mice, more than 75% of anti-NIP antibodies detected in their sera on day 8 were IgG. One cause of the high ratio of IgG/IgA antibodies detected in their sera on day 8 were IgG. One cause of the high rate of IgG/IgA antibodies in vivo is the efficient elimination of oligomeric IgA by the liver. Another possible cause is that the production of IgA is less sensitive than the production of IgG to the adverse conditions of the culture.

Separation of normal mature bone marrow plasma cells

A three-phase purification process for the separation of normal bone marrow plasma cells is described. Material was obtained from haematologically normal humans and baboons. Known monoclonal and polyclonal B cell activators were avoided both in vivo and in vitro. In Phase I, bone marrow fragments were separated from cell suspensions by buoyant density methods. Marrow fragments were shown to be richer in plasma cells than the corresponding marrow cell suspensions. Phase II consisted of culturing fragments by a simple suspension method in which a selective affinity of plasma cells and marrow stromal cells resulted in further concentration of plasma cells with discharge of haemopoietic elements. Maximum concentration of plasma cells occurred within 7 d. In phase III, fragments were disaggregated with trypsin, and the marrow stromal cells were removed by their adherence properties. The resulting non-adherent fraction comprised approximately 85% plasma cells. The process allows for direct quantitative evaluation of normal plasma cell physiology in vitro.

Immune reactivity during aging. I. T-helper dependent and independent antibody responses to different antigens, in vivo and in vitro

The immunological status during aging was assessed by measuring the antibody response of the long-lived (C3H/eb X C57Bl/6J)F1 mice to various antigens in vivo and in vitro. In vivo, a decrease in antibody production to DNP and NIP haptenic determinants coupled on to BGG, as well as the response to SRBC, was observed. The decline was more pronounced in the IgG as compared to IgM antibodies. The results were recorded when various parameters such as antigen dose and kinetics of the response, were considered. Reduction of the antibody response was also noted when PVP was employed as immunogen. Similar results were noted when the responses to SRBC and DNP--polylysine were induced and followed in spleen organ cultures. In all of these experimental systems, the peak response was observed in mice 6--12 months old. From then on a gradual decrease was manifested, mice 30--36 months old producing significantly low responses. The results demonstrate that decrease in antibody production is expressed in the isolated spleen tissue in the same manner as in the intact animal. Furthermore, they were interpreted as indicating that the lesion may be at the T helper and the B cell compartments.

Autoagglutinin produced by organ fragment cultures of mouse spleen

Mouse spleen fragment microcultures produced a heat-labile substance which agglutinated syngeneic erythrocytes. The substance reacted with an antigen present on some strains of mouse erythrocytes and on rat erythrocytes, but absent from other strains of mouse erythrocytes and from guinea pig, rabbit or sheep erythrocytes. Agglutination was inhibited by antisera to mouse immunoglobulins except for antisera specific to mouse IgM which enhanced agglutination. The agglutinin sedimented with 19 S Ig on ultracentrifugation and was destroyed by pretreatment with mercaptoethanol. Using a rosette assay increased numbers of cells, specifically binding syngeneic erythrocytes by means of a surface Ig receptor were demonstrated in spleen fragment microcultures. It is considered that the agglutinin is a noncomplement-activating IgM autoantibody and that the precursors of the cells producing the autoantibody are detected by the rosette assay.

Conditions for the development of IgM- and IgG-antibody-secreting cells from primed mouse splenocytes in vitro

A modified Marbrook chamber has been devised and manufactured which will fit inside a standard tissue culture Petri dish. A comparison has been made between Mishell-Dutton and modified Marbrook culture systems with respect to their ability to support an immune response by quiescent memory cells exposed to antigen in vitro. Good culture conditions are maintained for considerably longer in the modified Marbrook cultures and it seems that as a consequence these cultures support a large and reliable IgG response, normally absent or very small in cultures of the Mishell-Dutton type. Ease of manipulation and convenient size make the modified Marbrook system a good prospect for future long-term experiments.

In vitro activation of the in vivo colony-forming units of the mouse yolk sac

Experiments were performed to investigate the presence of colony-forming units (CFU) in the mouse embryonic yolk sac during the developmental period in which the yolk sac is the sole hemopoietic organ. Injection of yolk sac cell suspensions from normal embryos into syngeneic, lethally irradiated adult recipients evoked a very low number of spleen colonies. However, prior cultivation of yolk sacs in vitro caused a dramatic increase in the spleen colony-forming capacity--as high as 84-fold--following 48 hours in culture. The yolk sac origin of the spleen colonies was confirmed by: (a) Chromosomal marker analysis; (b) dose-response analysis; (c) demonstrating that the above colonies were not of endogenous origin induced by the mere injection of grafted cells. We conclude that the yolk sac contains many precursors of colony-forming cells which though undetectable by immediate grafting apparently become activated in culture by an as yet unknown induction process.

B-memory cells can be stimulated by antigen in vitro to become IgG antibody-secreting cells

Whereas DNP-KLH primed mouse spleen cells fail to show the high IgG anti DNP levels characteristic of an anamnestic immune response when cultured for 5 days under Mishell-Dutton conditions, we show here that such a response can be observed after 8--10 days in vitro using modified Marbrook culture vessels. The kinetics of this secondary response in vitro resemble that described elsewhere for the adotpive secondary immune response in irradiated recipients, and show that insignificant numbers of IgG PFC can be expected before 6 days of culture. This timing is governed by the maturation state of B cells at the start of culture, and was not accelerated by the addition of recently boosted carrier primed spleen cells. We conclude that the deficit in IgG PFC numbers that characterizes Mishell-Dutton cultures of cells primed 2--4 months previously is due to the shortage of time during which such cultures can maintain lymphocyte division and maturation.

Immune responses to hapten conjugates in vitro

Several functions of the animal body can take place in cell or tissue cultures with almost unreduced efficiency and precision. Functions, where only one cell type is involved, often do so, but also some differentiation steps where interactions between two or more cell types are clearly needed can take place in tissue culture (Saxén et al. 1968).

Most immune responses require collaboration between two or more cell types (Claman, Chaperon & Triplett, 1966; Miller & Mitchell, 1968; Feldmann & Nossal 1972c). Some of them can be easily induced in vitro but others cannot. Even when antibody responses can be induced in vitro their intensity varies a great deal. With some antigens and under some circumstances a response in vitro can be nearly as strong as one in vivo. A crude comparison can be derived from responses in vitro and in vivo to the same antigen, conjugate of hapten NIP and pneumococcal polysaccharide type III (NIP-SIll, Nakamura, Ray & Mäkelä, 1973).

Tolerance to heterologous erythrocytes

Injection of a water-soluble nonantigenic fraction obtained from lysed sheep red blood cells virtually abolishes the subsequent immune response to the red cells. The suppression is systemic and appears to be serum mediated.

Thymus-derived lymphocytes: humoral and cellular reactions distinguished by hydrocortisone

Lymphocytes derived from the thymus (T cells) take part in the induction of humoral antibody and also effect cell-mediated graft-versus-host reactions. Preliminary treatment of mice with hydrocortisone caused an inhibition of T-cell function in humoral immunity, while enhancing the graft-versus-host reactivity of the same population of spleen cells. This suggests that different types of T cells participate in cellular and humoral immune reactions.

The secondary immune response to a hapten in vitro. Antigen concentration and the carrier effect

The in vitro secondary stimulation of the production of anti-hapten antibody has been analyzed with a view to elucidating the role of the carrier molecule and cell-to-cell interactions in this response. Stimulation was carried out on fragment cultures of the spleens of irradiated BALB/c mice which had been reconstituted with 3-4 x 10(7) spleen cells from isologous mice previously immunized with DNP-Hy. The results indicated that the response was maximized by stimulation with DNP-Hy, the homologous complex, however anti-DNP antibody production could be obtained by stimulation with DNP on several nonhomologous carriers including poly-D-lysine, a poor immunogen. The results also indicated that while DNP-Hy and DNP-nonhomologous-carrier complexes were stimulatory at equally low DNP concentrations, at DNP concentrations over 10(-6)M DNP-Hy was stimulatory, while DNP on nonhomologous carriers was inhibitory. The results are interpreted as indicating that: (a) the affinity of the antigen-cell interaction is more likely determined by multivalent binding than by carrier recognition, (b) that a stimulatory interaction of a polyvalent antigen with a B-lymphocyte cannot be excluded, (c) that if cell-to-cell interaction is necessary for stimulation, then both cells may recognize the same determinant, and (d) that the marked enhancement of antigenic stimulation attributable to carrier recognition may result from stimulatory interactions of cells recognizing different antigenic determinants. A mechanism is postulated whereby stimulation is dependent on the formation of stable complexes resulting from two cells sharing in the binding of numerous antigen molecules. Cells recognizing carrier determinants would increase the probability of such interactions particularly at high antigen concentrations.

Chemical markers of transplantation individuality solubilized with sonic energy

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In vitro and in vivo studies of the immune response to sheep erythrocytes using partially purified cell preparations

The BSA density-gradient technique for separating mouse spleen cells into partially purified populations has been used to compare the responsiveness of such populations to SRBC using in vivo and in vitro techniques. Two major populations were distinguished, one of which responded very well in vivo with an exponential dose response and poorly in vitro (fraction 3), and another which responded in vivo and in vitro with a linear dose response (fraction 2). A light density, radiation-resistant component was identified which markedly stimulated the response of fraction 3 in vitro, and a density gradient profile was obtained for this cell which did not correspond with a macrophage profile. A high density, radiation-sensitive cell was identified which stimulated the response of PFC precursors in lighter regions of the gradient. The activity of this cell could be replaced using thymus cells. A density profile for the PFC precursor cell was obtained by assaying small numbers of spleen cell fractions in the presence of an excess of the two auxiliary cell types.

In vitro induction of a primary response to the dinitrophenyl determinant

Primary antibody response against the dinitrophenyl group has been elicited in vitro after the stimulation of normal mouse spleen explants with 2,4-dinitrophenyl (DNP)-hemocyanin or alpha-DNP-poly-L-lysine (PLL). Antibodies were detected in the culture medium by the inactivation of DNP-T4 phage. The specificity of the reaction was manifested by the lack of the capacity of the medium to inactivate the unmodified bacteriophage and by the inhibition of the inactivation of DNP-T4 with DNP-lysine.

Maturation of hemolysin-producing cell clones. I. The kinetics of the induction period of an in vitro hemolysin response to erythrocyte antigen

INVESTIGATIONS OF THE INDUCTION PERIOD OF AN IN VITRO HEMOLYSIN RESPONSE TO SHEEP ERYTHROCYTE ANTIGEN REVEALED THE FOLLOWING: 1. After antigen stimulation precursors of plaque-forming cells rapidly maturate to the point of hemolysin production. 2. Initial maturation probably occurs in the absence of cell division. 3. After initial maturation, a latent period of about 12 hr occurs before the first doubling of PFC. 4. At least the first three cell doublings are synchronous, with a generation time of 7-8 hr. 5. Synchronous cell division implies that all precursor cells are at the same point in the cell cyde when they are initially stimulated.

Immune responses in vitro. I. Cellular requirements for the immune response by nonprimed and primed spleen cells in vitro

A cell suspension culture system combined with a procedure which separates most macrophages from lymphoid cells was used to investigate some of the cellular requirements for direct and indirect plaque-forming cell responses by nonprimed and primed mouse spleen cells in vitro. The plaque-forming cell response to heterologous erythrocytes in cultures of nonprimed spleen cells required both macrophages and lymphoid cells for its development. A significant indirect plaque-forming cell response did not develop in cultures of nonprimed spleen cells. In contrast, cultures of separated or macrophage-poor lymphoid cells from primed mice exhibited increasing responses relative to the response of unseparated spleen cells as the interval after priming increased. The cultures of separated lymphoid cells were not entirely free of phagocytic cells. Despite some evidence which suggests that these phagocytic cells had little function in the response, one cannot ascertain whether the lymphoid cells were responding directly to a second contact with antigen or whether the few contaminating phagocytic cells were performing a function essential to the response by the lymphoid cells. Physiologically different populations of cells appear to develop after priming and are able to respond in vitro in a macrophage-poor culture. Some of the properties of these populations suggest that they are "memory cell" pools containing precursors of direct and indirect plaque-forming cells highly susceptible to a second antigenic stimulus.