Cellular recognition by mouse lymphocytes in vitro. I. Definition of a new technique and results of stimulation by phytohemagglutinin and specific antigens

Characterization of primary and memory CD8 T-cell responses against ranavirus (FV3) in Xenopus laevis

In mammals, resistance to primary and secondary viral infections critically involves major histocompatibility complex class I-restricted cytotoxic CD8+ T lymphocytes (CTLs). Although many gene homologues involved in CTL function have been identified in all vertebrate classes, antiviral CTL responses have been poorly characterized for ectothermic vertebrates. Because of the threat of emerging wildlife viral diseases to global biodiversity, fundamental research on comparative viral immunity has become crucial. Ranaviruses (family Iridoviridae) are double-stranded DNA viruses possibly implicated in the worldwide decline of amphibian populations. We used the frog Xenopus laevis as a model to evaluate adaptive immune responses to the ranavirus frog virus 3 (FV3). FV3 infects the kidneys of adults but is cleared within 4 weeks, with faster clearance upon secondary infections. In vivo depletion of CD8+ T cells markedly decreases the survival of adults after viral infection. To further investigate the involvement of anti-FV3 CD8+ T-cell effectors in host resistance in vivo, we determined the proliferation kinetics of CD8+ T cells in the spleen by bromodeoxyuridine incorporation and their infiltration of kidneys by immunohistology. Upon primary infection, CD8+ T cells significantly proliferate in the spleen and accumulate in infected kidneys from day 6 onward, in parallel with virus clearance. Earlier proliferation and infiltration associated with faster viral clearance were observed during a secondary infection. These results provide in vivo evidence of protective antigen-dependent CD8+ T-cell proliferation, recognition, and memory in fighting a natural pathogen in Xenopus.

Detection of novel carbohydrate binding activity of interleukin-1

Tamm-Horsfall glycoprotein (THGP) and the oligosaccharide fraction liberated from THGP by hydrazinolysis inhibited tetanus toxoid-induced T cell proliferation. Intact THGP showed approximately 100-fold more inhibitory activity than the free oligosaccharides. After fractionating the oligosaccharides by anion-exchange column chromatography, the inhibitory activity could be detected in a sialidase-resistant acidic oligosaccharide fraction (fraction AR). The inhibitory activity of fraction AR was not observed when the fraction was added to the T cell culture medium 24 h after the addition of tetanus toxoid. Increased concentration of interleukin (IL) 1beta and decreased concentration of IL-2 were observed in the T cell culture medium after the addition of fraction AR. The oligosaccharides in fraction AR also inhibited the growth of an IL-1-dependent cell line, D10-G4. These results strongly suggested that the oligosaccharides in fraction AR bind to IL-1beta and suppress its cytokine activity. IL-1beta actually bound to the fraction AR immobilized on an amino-bonded thin layer plate. Fractionation of the oligosaccharides indicated that only oligosaccharides containing an N-acetylgalactosamine residue and a sulfate residue bound specifically to IL-1beta. Removal of either the sulfate residue or the N-acetylgalactosamine residue from the oligosaccharides abolished both the proliferation-inhibition and IL-1beta binding activities. Since IL-1beta did not bind to thyroid-stimulating hormone, which has the sulfate group at C-4 of the N-acetylgalactosamine residue in its N-linked sugar chains, the binding of IL-1beta toward oligosaccharides in fraction AR was considered to be highly specific.

Mitogen-activated Xenopus laevis lymphocytes produce a T-cell growth factor

Mitogen-free and serum-free supernatants (SNs) from cultures of phytohaemagglutinin (PHA)-stimulated Xenopus splenocytes, co-stimulated thymocytes, induced proliferation of splenic and thymic lymphoblast and supported growth of alloreactive T-cell lines. These SNs had no effect on 'resting' splenocytes, as measured by uptake of tritiated thymidine ([3H]TdR). Growth-promoting activity was also detected in SNs of cultures containing alloreactive T-cell lines and either PHA or irradiated stimulator cells that expressed the original priming alloantigens. Thus, T lymphocytes appear to be involved in producing, as well as responding to, a Xenopus T-cell growth factor (TCGF). TCGF activity could be absorbed from these active SNs with PHA-activated splenic blasts. No functional cross-reactivity among different mammalian interleukin-2 (IL-2) and Xenopus TCGF preparations was detected.

Basal and lipopolysaccharide-inducible membrane alkaline phosphatase of lymphoid cells from mice with immune system dysfunctions

The expression of membrane alkaline phosphatase (mAlPase) activity is an enzymatic marker of activated but not resting B cells which can be used on unseparated lymphoid cell suspensions. It is higher in lymphoid cell suspensions from mice with higher proportions of B cells (athymic mice) or with more activated B cells (autoimmune mice) than in those of control mice.

Cellular immune mechanisms in thermally injured mice

An attempt was made to establish an animal model for analysing the cellular immune alterations following thermal injury and to correlate the results with those obtained in humans. A standard burn involving 20 per cent of the body surface area was established in C57 black mice (b1). The results revealed a loss of total T cells until post-burn day 10 and an increase in B cells only during post-burn day 1. The lymphocyte proliferative response to PHA was elevated with the appearance of null cells on post-burn day 10. This observation revealed a generalized depression in the immune responses which was significant until post-burn day 10. However, the results were not comparable with the human studies.

Functional disability of rat splenocytes provoked to lipid peroxidation by cumene hydroperoxide

Rat splenocytes were provoked to lipid peroxidation in a dose-dependent manner by cumene hydroperoxide. After exposure to cumene hydroperoxide, formation of high molecular weight protein, presumably through cross-linking of lower molecular weight protein, was stimulated in splenocytes as well as in erythrocyte ghosts. The mitogenic response to concanavalin A of splenocytes was remarkably depressed by addition of cumene hydroperoxide to cultures. This depression was due rather to failures of splenocytes in responding to concanavalin A than deactivation of concanavalin A molecules. It is notworthy that the viability of splenocytes was unaffected by cumene hydroperoxide under the culture conditions where the mitogenic response was depressed. The addition of alpha-tocopherol or thiourea could block the depression of mitogenic response by cumene hydroperoxide, indicating that the depressed response to concanavalin A was related to radical formation. Overall evidence suggests that the function of immunocompetent cells can be depressed through lipid peroxidation-associated mechanisms without suffering from lethal damage.

During frog ontogeny, PHA and Con A responsiveness of splenocytes precedes that of thymocytes

The in-vitro proliferation of splenocytes and thymocytes from Xenopus laevis-gilli (hybrid clone LG-15) to the T cell mitogens, concanavalin A (Con A) and phytohaemagglutinin-P (PHA), were examined at specific stages of larval development (stages 51-66 of Nieuwkoop & Faber, 1967) and at 2 months post-metamorphosis. The responses of splenic lymphocytes to each mitogen were significant at all stages with stimulation indices ranging from 1.9 to 50.5 and 2.6 to 45.5 for PHA and Con A, respectively. Stage-related differences in responses of splenocytes to both mitogens suggest two waves of emergence of proliferative activity during development, divided by periods of diminished responsiveness during the metamorphic crisis. In contrast to the responses observed with splenocytes, proliferation of thymocytes cultured with either mitogen was barely detectable, with stimulation indices ranging from 1.2 to 6.9 and 1.4 to 2.9 for PHA and Con A, respectively. These minimal responses were observed only when thymocytes were cultured at relatively high cell density (5 X 10(5) cells/ml); they were not improved by increased or decreased concentrations of mitogen or by increased concentrations of fetal calf serum (5 or 10%) in the medium. Co-culture of larval thymocytes with autologous splenocytes and each mitogen did not consistently increase thymocyte responses suggesting that the defect in thymocyte responsiveness is not due to lack of accessory cells. These findings suggest that if PHA- and Con A-reactive cells are present in the thymus, they are present in relatively low numbers at all stages of larval development. The pattern of early mitogen responsiveness in the spleen at a time when the thymus is unresponsive contrasts with that observed in mammalian development in which thymocytes become responsive to mitogens in fetal stages and mitogen responsiveness appears in the spleen only around the time of birth. The apparent inactivity of larval thymocytes may reflect a population of cells that can become tolerant to those neo-self-antigens that arise during and after metamorphosis. If so, the larval amphibian thymus may provide a model to study the early events of thymocyte 'education' and differentiation in a broader time framework than is possible with fetal mammals.

Non-specific immunosuppression by Cryptococcus neoformans infection

Cryptococcus neoformans-infected animals were found to be immunosuppressed when tested by a variety of assays for immune competence. Primary humoral immune responses and delayed-type hypersensitivity reactions to sheep erythrocytes were suppressed in animals which had been infected for two weeks. Lymphocyte proliferation (LP) assays to sRBC stroma were also significantly diminished at two weeks of infection. Spleen cells of infected mice suppressed the LP response of sRBC immunized, normal mice in vitro. At least a part of the suppression could be attributed to a nylon wool non-adherent cell. Suppressor cells continued to be present in spleen cell suspensions following treatment with anti-T cell serum or anti-immunoglobulin and complement. When infected spleen cells were separated by adherence to plastic, both the adherent and non-adherent fractions exhibited suppressive activity. Incubation of infected spleen cells in tissue culture for 48 hr resulted in the elaboration of soluble immunosuppressive factors into the tissue culture medium. These data indicated that immune suppression in cryptococcosis can occur as a result of infection with Cryptococcus neoformans, and that at least one mechanism involved is the induction of adherent and non-adherent suppressor cells in the spleens of infected mice.

In vitro viability of lymphoid cells from lines of mice genetically selected for high or low responsiveness to phytohemagglutinin

The kinetics of viability of lymph node and spleen cells of mice genetically selected for "high" or "low" in vitro lymphocyte responsiveness to PHA were studied in PHA or PPD-stimulated short-term cultures. Lo/PHA cells were found to be less viable than Hi/PHA cells in unstimulated control cultures. PHA improved the viability of Lo/PHA cells while inducing proliferation of Hi/PHA cells with the appearance of more and larger lymphoblasts in the latter. PPD only improved the viability of spleen cell cultures, more so for the Hi/PHA line. The interline difference in thymidine uptake was smaller after PPD than after PHA stimulation. Modifications of culture conditions designed to decrease the interline difference in cell viability lessened but did not abolish the separation between the two lines for the PHA response as measured by thymidine uptake.

The effect of tri-iodothyronine on the phytohaemagglutinin response of T lymphocytes

Tri-iodothyronine has been shown to affect murine lymphocyte responses to phytohaemagglutinin in vitro. These results coupled with previously obtained results on the effect of thyroid hormone on humoral responses suggest a possible novel approach to immunization.

Human lymphocyte transformation induced by mitogens and antigens in a serum-free tissue culture system

The use of serum to supplement lymphocyte tissue culture media introduces uncontrolled variables; different serum sources, lots and concentrations can produce variability in experimental results, serum can stimulate or inhibit lymphocytes, and components of serum can react with substances whose effects on lymphocytes are being studied. To avoid these problems, we studied the ability of human peripheral mononuclear cells to survive and to respond to stimulation in an entirely synthetic medium, RPMI-1640 supplemented with L-glutamine, gentamicin, HEPES buffer and magnesium. Optimal cell concentration in this serum-free RPMI-1640 was 2.5 x 10(6) cells/ml, whereas optimal cell concentration in serum containing RPMI-1640 was 1 x 10(6) cells/ml. In this serum-free RPMI-1640, 50% of the cellular input was recovered as viable cells after 7 days of culture, which was similar to results in serum containing RPMI-1640. Mononuclear cell transformation transformation was induced by phytohemagglutinin, concanavalin A, pokeweed mitogen, streptolysin O and candida. Optimal doses of stimulants and the kinetics of the responses were similar in serum-free and serum containing RPMI-1640. This system can be used to avoid the problems inherent in systems which supplement tissue culture media with serum.

Immune response to chemically induced tumours: correlation of responding cell class with in vivo inhibition of tumour growth

Lymphoid cells stimulated by soluble tumour antigens in the MCA-induced murine fibrosarcoma system have been identified by subclass and protective capacity in adoptive syngeneic hosts. Lymph-node or spleen cells taken at weekly intervals after inoculation of syngeneic chemically induced fibrosarcomas were enriched by 3 methods in T, B, and "null" cell subclasses, and assayed for proliferative kinetics in response to soluble membrane antigens. The stimulated subpopulations were found to be heterogeneous, their composition varying with time and tumour burden. Initial proliferative responses after tumour inoculation were limited to the T-enriched subpopulation. Later during tumour growth, T, B and null cell fractions were vigorously and equally stimulated by tumour antigen. The ability of the same T, B or null-cell subpopulations to inhibit tumour growth was measured in adoptive hosts by a modified Winn assay. Only the T-cell subpopulation responding to tumour antigen in vitro effectively and consistently retarded tumour growth in vivo. In contrast to the shared specificities on syngeneic tumours identified by the proliferative assay, tumour-growth inhibition was limited to the specific tumour borne by the cell donor.

Differences in mitogenic responses of murine T cells to two distinct phytohemagglutinin (PHA) subcomponents

Two distinct mitogenic subcomponents of phytohemagglutinin (PHA)--leucoagglutinin (LA) and "purified" PHA--apparently stimulated different subpopulations of murine T cells. In the DBA/2J strain, the mitogenic responses of splenic lymphocytes to LA reached maximal levels after 24 to 36 hr exposure and almost completely disappeared by 48 hr, whereas maximal responses to PHA were maintained after 48 hr incubation. The levels of LA-responding T cells were highest in DBA/2J spleens at 5 weeks of age but markedly declined by 9 weeks of age, whereas thymic levels of LA-responding T cells reached a maximum at 9 weeks of age and remained maximal past 15 weeks of age. PHA-responding cells, in contrast, reached maximal levels in both the spleen and thymus of DBA/2J mice at 9 weeks of age. In C57BL/6J mice, splenic and thymic lymphocytes responded similarly to both components, except that the response of splenic lymphocytes to PHA reached a maximum after shorter incubation time and declined sooner than their response to LA. The mitogenic responses of C57BL/6J thymocytes to both components were already at their peak by 5 weeks of age and almost totally disappeared by 9 weeks, whereas the responses of splenic lymphocytes were maximal at 9-15 weeks of age. The responses of DBA/2J splenocytes to LA was significantly augmented by PHA, but LA markedly suppressed the proliferative responses to PHA.

Cytotoxicity of Echinococcus granulosus cyst fluid in vitro

In a cytotoxicity assay, using rat spleen cells as target cells, Echinococcus granulosus cyst fluid from cattle exerted a marked degree of cytotoxicity in vitro. When trypan blue exclusion or [3H]thymidine incorporation by concanavalin A stimulated spleen cells was used as a measure of cell viability, dialyzed cyst fluid showed maximum cell destruction up to a 1:8 dilution. The effect was dose and time dependent, cells being affected by 24 h after exposure to cyst fluid. The components responsible for cytotoxicity of cyst fluid were heat stable and could be recovered using gel chromatography on Sephadex G 50 and G 15 as a single low molecular weight fraction. It is assumed that the toxic products released by the living parasite can readily penetrate through the cyst wall into the surrounding host tissue. The interference of such substances with immunocompetent cells might account for the long-term survival of the parasite in the intermediate host.

Immunological evaluation of the tumorigenic response to implanted polymers

This short report concentrates on a close look at the immunological status of experimental animals which were implanted with a known dose of tumor and polymer implant. The implanted polymers used represented the most common biocompatible materials employed in current surgery. The immunological studies all were done in vitro on the cellular level. The studies suggested that there is a noticeable change of the immune system when inorganic biocompatible polymers are used in experimental animals.

Protease potentiation of thymocyte blastogenesis

When rat thymocytes were cultured with concanavalin A (con A), addition of trypsin increased the incorporation of [³H]-thymidine (³H-TdR) several fold over that observed with mitogen alone. The potentiating effect of trypsin was greatest with suboptimal concentrations of mitogen, less with optimal, and least with superoptimal concentrations. Trypsin also increased blastogenesis and stimulated [³H]-leucine incorporation into thymocyte proteins. Thymocytes cultured with trypsin in the absence of mitogen sometimes showed increased ³H-TdR incorporation but the increase was usually small and not consistent. The potentiating action of trypsin is due to its proteolytic activity since it was completely blocked by soybean trypsin inhibitor. Elastase, α-chymotrypsin, and subtilisin also potentiated the action of con A, while papain, collagenase, thrombin, and plasmin had either very little or no effect. Trypsin potentiated ³H-TdR incorporation into thymocytes cultured in serum-free or serum-supplemented media, but its effects were usually greater in media supplemented with 5% autologous serum. Although heating serum at 56° for 0.5 or 2 h markedly reduced stimulation by con A, the effects of trypsin were relatively greater in media supplemented with heated serum. The possible physiological significance of the results was discussed with respect to protease secretion by macrophages and lymphocyte—macrophage interactions.

A Y chromosome associated factor in strain BXSB producing accelerated autoimmunity and lymphoproliferation

Strain BXSB/Mp mice develop a spontaneous lupus-like syndrome which is strikingly accelerated in males. The accelerated autoimmune disease occurs in male F1 hybrids with strains NZB/BINJ, SJL/J, and C57BL/6J when the male parent is BXSB but not in the reciprocal hybrid male nor in females. The pattern is similar in F2 hybrids with strains NZB and SJL. The accelerated disease in males occurs only when the Y chromosome is derived from recombinant inbred strain BXSB and ultimately from strain SB/Le.

Deficient cutaneous response to PHA-P in healthy puppies from a kennel with a high prevalence of demodicosis

Intradermal injection of phytohemagglutinin was used to evaluate the integrity of cell-mediated immunological reactions in Doberman puppies thought to be predisposed to demodicosis. Results indicate a statistically significant deficiency of cutaneous delayed response in these dogs when compared with age matched Beagles, adult Dobermans or random control dogs of various ages and breeding. The high prevalence of demodicosis in the kennel of origin may have been due to the observed deficiency of cutaneous immune function.

Differences in [3H]-thymidine uptake of lymph node cells stimulated by Con A and PHA in H-2 congenic mouse strains

The genetic control of the lymphocyte responsiveness to Con A and PHA-P has been studied by using inbred, H-2 congenic mouse strains. Segregation studies were carried out on F1 and backcross mice of a high and a low responder strain. According to the results, there is a strong correlation between the responsiveness of lymph node cells to mitogens and H-2 haplotypes in different H-2 congenic strains of mice and in different backcross generations. High responsiveness to PHA-P is associated with H-2b, while low responsiveness with H-2a or H-2k haplotypes, but the correlation is the inverse in response to Con A, in the parental strains and backcross mice as well. The magnitude of the responses to both Con A and PHA-P was found to be intermediate in F1 heterozygotes of a low and high responder parental strain. The effect of other non H-2 genes on the responsiveness to these mitogens has also been demonstrated.

Laboratory studies on the immune effects of halogenated aromatics

The effects of TCDD exposure on the developing immune system were investigated in Wistar/Fischer hybrid or Fischer rats. Fetal and neonatal rats were exposed to TCDD through maternal dosing (5 muk/kg) on day 18 of gestation and on days 0, 7, and 14 of postnatal life (group 1). Another group of neonatal rats was exposed to TCDD through maternal dosing on days 0, 7, and 14 of postnatal life only (group 2). Variable but significant effects on body weights and thymus/body weight ratios were found up to 133 days of age. Cell mediated immune functions were depressed up to 133 days of age in both groups but less severely in animals exposed only postnatally. Furthermore, TCDD suppressed cell-mediated immune functions without affecting humoral immune function. Adoptive cell transfer studies indicated suppression of T-cell functions was selective in that "helper" cell function was not suppressed. In other studies, the effects on lymphocyte function following brief exposure of spleens from B6C3F1 mice to TCDD in dimethylsulfoxide (DMSO) were investigated. DNA, RNA and protein synthesis were inhibited at concentrations less than 2 X 10(-7) M TCDD in DMSO. This concentration accounted for approximately 0.2 ng TCDD uptake per spleen. The structurally related chemicals 3,4,3',4'-tetrachlorobiphenyl and 1-amino, 3,7,8-trichlorodibenzop-p-dioxin did not show significant lymphocyte effects even at two-fold higher concentrations. The ability of lymphocyte mitogens to bind to their cell surface receptors was not affected by TCDD treatment. TCDD was slightly cytolytic to lymphocytes after 48 hours of culture. DMSO treatment alone was also slightly toxic to lymphoid cells as indicated by a 10--20% loss of cell viability, although this occurred within 4 hours after DMSO exposure. Studies were performed to investigate the effects of 2,3,7,8-tetrachlorodibenzofuran (TCDF) on immune function in adult Hartley guinea pigs. Animals received 6 weekly doses of either 0, 0.05, 0.17, 0.5 or 1.0 microgram TCDF/kg body weight. TCDF slightly depressed cell-mediated immune functions, particularly at the higher dose levels as indicated by decreased lymphocyte blastogenesis, delayed hypersensitivity reactions, and production of macrophage inhibitor factor. Additionally, thymus-to-body-weight ratios were slightly reduced in the 0.5 and 1.0 microgram dosage groups. Serum IgG levels and antibody titer to BGG did not differ from controls. These results indicate that TCDF-induced immunosuppression is similar to that of TCDD.

Influence of supernatants from polymorphonuclear leucocytes on blastogenesis of syngeneic and allogeneic murine splenocytes

Supernatant was produced from activated peritoneal polymorphonuclear leucocyte-rich cell populations from different strains of mice. These supernatants were studied for their ability to modify spontaneous and mitogen-induced blastogenesis of syngeneic and allogeneic splenocytes. Our results indicate that polymorphonuclear leucocyte-rich cell cultures from two strains of mice, A/J and BALB/c, produced a supernatant that could enhance PHA-induced blastogenesis of syngeneic and allogeneic splenocytes. Cells from a third strain C57B1/6, did not produce an active supernatant. In general, the response by splenocytes from these three strains paralleled the production of active supernatant that we observed. The response to the active supernatant was dependent upon the mitogen stimulation of the splenocytes, the mitogen dilution and the supernatant activity. These functions are believed to be genetically determined.

Development of antigen-induced proliferative responsiveness by murine lymph node cells. I. Identification of differences in the in vitro proliferative responses during a first and a second period of responsiveness

The development and course of antigen-induced proliferative responsiveness by murine lymph node cells (LNC) was observed for 16 weeks post-immunization. The initial phase of responsiveness was characterized by antigen-induced proliferative responsiveness in vitro which reached a maximum 3-5 weeks post-immunization and then declined to low levels by 6-8 weeks. Without injection of additional antigen, the initial phase of responsiveness was followed by the development of a second phase of antigen-induced proliferative responsiveness 10-12 weeks post-immunization. These findings suggest that the in vivo development of lymph node lymphocytes capable of a proliferative response to antigen is under some type of modulation which is maximal 6-8 weeks post-immunization. Early in the first phase the proliferative responses to higher concentrations of antigen peaked early in the culture period (days 3-4), whereas responses to the lower concentrations of antigen were optimal after 5-6 days of culture. During the latter half of the first phase, however, peak proliferative responses were made to all the concentrations of antigen on the same day of culture (day 6). In contrast, the responses detected at the beginning and throughout the second phase of responsiveness were characterized by maximum proliferation to all the concentrations of antigen late in the culture period (day 7). These results delineate the temporal requirements for maturation of antigen-induced proliferative responsiveness of murine LNC post-immunization and indicate the time interval when optimal responses may be detected.

The immunosuppressive and mitogenic effects of Trypanosoma musculi

In CD-1 mice infected with Trypanosoma musculi, the production of IgM and IgG antibodies in response to sheep erythrocytes (SRBC) was significantly suppressed when mice were immunized with SRBC once high parasitaemias had developed. In infected mice which were not immunized with SRBC, background plaque-forming responses of spleen cells to SRBC were significantly higher than in uninfected, unimmunized mice. Factors derived from T. musculi were found to be mitogenic in vitro for spleen cells taken from CD-1 mice. The mitogenic response to these factors by spleen cells from athymic mice was highly significant, whereas the response of spleen cells taken from CD-1 mice which had been pre-treated with cyclophosphamide was much less, suggesting that the B cell was the major target of the trypanosome-derived mitogen. In this paper we discuss the possible relationship of T. musculi-induced mitogenesis to the immunosuppression and non-specific antibody formation associated with T. musculi infections.

Effect of concurrent cytomegaloviral infection and undernutrition on the growth and immune response of mice

Mice were inoculated with murine cytomegalovirus (MCMV) passaged in cell cultures within 24 h of birth and subsequently fed an adequate or a low-protein diet after weaning; increases in body weight, the blastogenic response of lymphocytes to T and B cell mitogens, and the capability to produce antibodies to T or B cell-dependent antigens were observed for the first 28 to 42 days of life. Neonatal infection resulted in immunosuppression and retarded physical growth through the first 4 weeks of life. After weaning (3 weeks), the effect of MCMV infection of well-nourished mice paralleled the effect of undernutrition in uninfected animals. Undernutrition and MCMV infection functioned synergistically.

Optimal macroculture method for studying mitogenic stimulation of turkey lymphocytes

This report describes a method for culturing turkey lymphocytes in disposable, unwashed glass test tubes with Morton closures and for recovering lymphocytes on fiber glass filters with a cell harvester made of common laboratory equipment for assay of mitogenic stimulation. Optimal conditions for culture were established.

Mitogenicity of autolysates of Trypanosoma congolense

Autolysates of Trypanosoma congolense, in subcytotoxic amounts, were found to be highly mitogenic in vitro for the spleen cells of normal mice. Significant amounts of [3H]-thymidine were also incorporated by the responding spleen cells of nu/nu (athymic) mice. In contrast, the spleen cells of cyclophosphamide-treated mice were unresponsive. The findings suggest that a potent B-cell-mitogen is generated by the autolysing T. congolense organism.

Mitogenic activity of bacterial lipopolysaccharides in vivo: morphological and functinal characterization of responding cells

The in vivo effect of bacterial lipopolysaccharides (LPS) on mouse spleen cell subpopulations was investigated. Intravenous administration of LPS resulted in marked enlargement of the spleen, accompanied by increased cellular proliferation and enhanced nucleated cell recoveries. At least two morphologically distinct cell types appeared to be targets for LPS. Polymorphonuclear leukocytes accumulated rapidly with a relatively minor degree of cell division. In contrast, a substantial proportion of splenic lymphocytes transformed into large lymphocytes and blast cells which actively incorporated [3H]thymidine. Proliferating cells were identified as bone marrow-derived (B) lymphocytes by their ability to form C3-dependent rosettes and to synthesize immunoglobulin. These cellular responses were not antigenically induced, since LPS derived from mutants lacking the polysaccharide moiety gave similar results. Thus, splenic B lymphocytes appear to interact and respond to LPS in vivo in the same manner as observed in vitro. These data suggest that the capacity of LPS to directly activate B lymphocytes, initiate cellular proliferation, and induce immunoglobulin production by bone marrow-derived cells in vivo may contribute to its adjuvant activity.

An endotoxin induced serum factor that causes enhancement of antibody response to heterologous erythrocytes

The sera obtained from blood of the mice, which had been intravenously injected with LPS several hours in advance, contained some active substance capable of enhancing anti-sheep red blood cell (SRBC) antibody responses in mice. Activity of the sera was still retained after passage through a rabbit anti-LPS antibody-coated Sepharose 4B column, but greatly reduced by passage through a rabbit anti-mouse thymocyte antibody-coated Sepharose 4B column. The active substance in the sera was eluted through a Sephadex G-200 column at the same position as the serum albumin. The addition of this substance to B cell rich spleen cell cultures in vitro in the presence of SRBC generated tremendous numbers of antibody forming cells 4 days after the incubation, suggesting that this substance was able to take over the helper function of T cells in thymus dependent antibody responses. However, this substance was not capable of stimulating 3H-thymidine-uptake into cultured spleen cells. The possible role of this substance in the adjuvant effect of LPS is discussed.

Impairment of thymus-dependent immune functions by exposure of the developing immune system to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

The effects of TCDD exposure on the developing immune system were investigated in F344 rats. Fetal and neonatal rats were exposed to TCDD through maternal dosing (5 microgram/kg) on day 18 of gestation and on days 0, 7, and 14 of postnatal life (group I). Another group of neonatal rats was exposed to TCDD through maternal dosing on days 0, 7, and 14 of postnatal life only (group II). Body weights and thymus/body weight ratios were found to be suppressed up to 145 days of age in group I, but only up to 39 days of age in group II. Parameters of cell-mediated and humoral immune function were investigated. TCDD suppressed cell-mediated immune function without affecting humoral immune function. Suppression of T-cell function was selective in that "helper" cell function was not suppressed.