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A mean of 6.9 per cent of small lymphocytes in peripheral blood preparations and between 1.8 and 2.4 per cent of small lymphocytes in lymph node, spleen, bone marrow and thymus preparations from unimmunized guinea-pigs bound 125I-labelled purified protein derivative of mammalian tuberculin (mammalian PPD). The percentage of these cells fluctuated but did not alter substantially after immunization with BCG or with BCG emulsified with human thyroglobulin (HTg) in Freund's incomplete adjuvant (FIA). Blocking experiments indicated that the binding of 125I-labelled mammalian PPD was specific and there was tentative evidence that the lymphocyte receptors may be IgG. A comparison is drawn between the observed time course of 125I-labelled mammalian PPD- binding small lymphocytes and the response of lymphocytes sensitive to strong histocompatibility antigens, and it is proposed that the propensity of certain anti- gens to induce a delayed hypersensitivity-type response is related to the presence of substantial numbers of antigen-binding cells in unimmunized animals. A noteworthy incidental finding was an unexplained depression in the cellular and humoral responses to mammalian PPD in guinea-pigs that had been immunized with HTg-BCG-FIA emulsion. [ABSTRACT FROM AUTHOR]

The restorative action of developmental hormones, mainly somatotropic hormone, and of lymphnode lymphocytes on the immunologically crippled hypopituitary Snell-Bagg dwarf mouse is evaluated. The hormonal treatment can completely reconstitute the structure of the thymus and of the peripheral lymphoid tissues. Both hormones and mature lymphocytes restore the impaired capacity of the dwarf mouse to propuce antibody and to reject skin allografts. Normal donor thymocytes and bone marrow cells alone or in combination fail to produce the same effect in absence of a hormonal treatment. The action of hormones is not exerted if dwarf mice are thymectomized in adult age. This and other evidence shows that the action of hormones is mediated through the thymus and leads to the formation of longliving lymphocytes. [ABSTRACT FROM AUTHOR]

The article informs that the there are no reliable quantitative indices of the "functional capacity" of the immunological system in man. The occurrence of infections, the levels of immunoglobulins, the elicitation of coetaneous delayed hypersensitivity reactions, and the antibody response to various vaccine antigens have all been used, but standard routine methods have not been developed. This paper describes an attempt lo use antibody production to flagellin as one index of the functional capacity of the immune system, and describes the response in subjects considered to have a normal antibody-producing system.

Highly purified blood lymphocytes from treated and untreated patients with plasmacell myeloma were tested for the presence of *EAC lymphocytes carrying the C3 receptor surface marker using a rosette-technique and for thymus-derived (T) lymphocytes as judged by spontaneous rosette formation with sheep red blood cells. The treated patients were tested 5 weeks after a standardized 4-day treatment with melphalan and prednisolone. Untreated patients had 40-65% EAC-lymphocytes in peripheral blood while the EAC-cell level in treated patients was < 20%. A non-myeloma control group had 20-40%. The percentage of EAC-lymphocytes was correlated with different in vitro functional tests: lymphocyte-mediated lysis of target cells (Chang cell line or chicken red blood cells) treated with rabbit antibody correlated with the percentage of EAC-lymphocytes. DNA synthesis induced in lymphocytes by pokeweed mitogen (PWM) showed a biphasic dose response curve which may indicate activition of two populations of lymphocytes. A correlation was found between EAC-lymphocytes and DNA synthesis induced by a low concentration of PWM (0.1 μg/ml). The results support observations by other investigators which suggest that antibody-induced cytotoxicity requires cells in the non-T-lymphocyte population and the assumption that PWM is in part a mitogen for human bone marrow-derived lymphocytes. [ABSTRACT FROM AUTHOR]

Bone marrow cells and thymus cells were observed in cell transfer expehments to collaborate in the production of anti-BSA antibodies. The target cells for tolerance induction either with a 'low dose' of antigen (100 µg of deaggregated BSA once a week × 5) or with a 'high dose' (a single injection of 5000 µg) were identified by the same technique. In 'low dose' tolerance, some indication was obtained that thymus-derived cells in peripheral lymphoid systems were the target cells; bone marrow-derived cells appeared not to be so susceptible, and the cells residing in thymus or bone marrow seemed to remain unimpaired, in contrast, the injection of a 'high dose' of tolerogen rendered both types of cells in spleen, thymus cells and bone marrow cells, unresponsive or hyporesponsive in parallel with one another. [ABSTRACT FROM AUTHOR]

Peritoneal exudate lymphocytes (PEL) of guinea-pigs injected with Freund's complete adjuvant (FCA) were capable of liberating skin reactive factor (SRF) and macrophage migration-inhibitory factor (MIF) when cultured for 24 hours in the presence of sheep red cells (SRC) preincubated with lymph node cells (LNC) of guinea-pigs immunized with SRC in FCA. Similar release of soluble mediators was found in the following situations: (a) incubation of non-immune PEL with SRC sensitized with the exclusion peak of Sephadex G-200 fractionated immune LNC supernatant; (b) incubation of non-immune LNC with complexes of SRC and anti-SRC IgG, prepared from serum of animals immunized with SRC in CFA, and (c) incubation of non-immune LNC with a mixture of SRc urea extract and anti-SRC IgG. SRC incubated for 24 hours with immune LNC and freed of lymphocytes by selective filtration through a Millipore filter, were able to provoke an inflammatory reaction in the skin of normal guinea-pigs, which was delayed in character. These findings are interpreted as suggestive evidence for the non-identity of the mediator-producing and antigen-reactive cells and as support for the hypothesis that a complex composed of antigen and an antibody-like material, secreted by stimulated antigen-reactive lymphocutes, is responsible for the release of soluble mediators in cell-mediated immune reactions. [ABSTRACT FROM AUTHOR]

Bone marrow-thymus cooperation experiments were carried out in lethally irradiated mice with sheep red blood cells (SRBC) as the antigen and direct plaque-forming cells (PFC) as the end point. Various parameters were altered, with the following results: (1) Above 800 rad, the response by marrow cells alone, as well as the increase due to added thymus cells, was independent of irradiation dose. (2) The response of marrow cells was greatest at high SRBC concentrations, but the co-operative effect of thymus cells was most evident at lower SRBC levels, and completely absent at high levels. (3) Increasing the number of marrow cells, without thymus, gave increasing numbers of PFC, but the dose-response curve did not suggest cell synergism. (4) Thymectomy and antithymocyte serum treatment of host or donor did not prevent the response by marrow cells alone. It was concluded that this was a true IgM response by antibody-forming precursors from the marrow, unaided by thymus-derived cells. [ABSTRACT FROM AUTHOR]

Lymph node tissue from guinea-pigs immunized against one of several antigens was cultured in different media in order to determine conditions under which maximal amounts of antibody are formed in vitro. The amounts of antibody formed were variable and bore no relation m the level of serum antibody in the tissue donor. Heterologous sera of several origins, when included in the culture medium, varied very markedly in their capacity to support antibody production in vitro. [ABSTRACT FROM AUTHOR]

Immunological competence in sarcoidosis was measured by in vivo and in vitro immunological testing of eighteen subjects who had never been treated with prednisone, and eleven subjects treated with prednisone. Three of the latter group had been studied before steroid therapy. Cutaneous delayed hypersensitivity was assessed by intradermal skin testing with five antigens. Thymus-derived 'T' lymphocytes and bone marrow-derived 'B' lymphocytes were enumerated and the ability of lymphocytes to respond to stimulation with phytohaemagglutinin (PHA), Candida albicans and allogeneic irradiated lymphocytes (mixed lymphocyte reaction) was measured and compared to results obtained with lymphocytes from healthy subjects. The non-steroid-treated and the steroid-treated groups did not respond as well as a control group to intradermal challenge. The responses of lymphocytes from patients with untreated sarcoidosis to PHA and Candida albicans was normal but the response to allogeneic lymphocytes was reduced. In comparisons stimulation indices for lymphocytes from the group who were receiving steroids were significantly reduced, with eight of eleven individuals having abnormal responses. Significant reduction in T lymphocytes was observed in only three of eleven of the non-steroid-treated subjects and five of ten of the steroid-treated subjects that were studied. Studies on patients before and after steroid therapy suggest that steroid therapy and not sarcoidosis was responsible for the poorer responses of the steroid-treated group. The most striking findings of this study was the marked disparity between the cutaneous reactivity to Candida albicans, which was abnormal, and the in vitro lymphocytes response to this antigen which was normal. This suggest that the anergy of sarcoidosis cannot be attributed to an inherent lymphocyte dysfunction or to a depletion of these cells. [ABSTRACT FROM AUTHOR]

Injection of neonatal Balb/c or C57B1/6 mice with (C57B1/6x Balb/c)F1 lymphoid cells leads to transient chimerism and runting, and to splenomegaly, deficient T-cell function and a gradual replacement of lymphoid organs with abnormal reticular cells. Activated MuLV can be isolated from such mice. It is proposed that either graft-versus-host or host-versus-graft allogeneic reactivity activates endogenous MuLV virus, which then causes functional and morphological abnormalities in the lymphoid organs. [ABSTRACT FROM AUTHOR]

Fourteen days after injection with Detroit-6 cells (a human cell line) rats have high titres of antibody capable of inducing cytotoxicity towards Detroit-6 cells in normal spleen cells. At the same time, the spleen cells from the injected rats are cytotoxic for Detroit-6 cells in vitro. However, killing by allergized spleen cells is apparently not entirely antibody induced, since heterologous anti-thymocyte sera (absorbed with rat bone marrow cells) inhibit target cell killing by spleen cells from injected rats but do not appreciably inhibit killing of antibody-coated target cells by normal spleen cells. Wistar spleen cells 'activated' by transfer into irradiated August rats are cytotoxic for August hepatoma cells. This cytotoxicity is also inhibited by the absorbed anti-thymocyte sera. It is suggested that the cytotoxicity of spleen cells in vitro, in both these allogeneic and xenogeneic systems, is mediated by thymus-derived (T) cells. [ABSTRACT FROM AUTHOR]

Newly synthesized DNA has been shown to be released by immunized rabbit spleen tissue cultured in vitro. This DNA was mainly double-stranded, showed a large spread in buoyant density, and was in the molecular weight range 50,000-500,000. Rabbit spleen tissue and human peripheral blood lymphocytes in active DNA synthesis, also took up bacterial DNA into their nuclei. After short periods of culture this DNA had a buoyant density of the bacterial DNA employed. Upon prolonged incubation, the DNA was of mammalian density. Evidence was obtained, in the case of the blood lymphocytes, for the appearance in the cells of a DNA of intermediate buoyant density. The possible relevance of the loss and reutilization of DNA to lymphoid cell function is discussed. [ABSTRACT FROM AUTHOR]

The functional integrity of the mononuclear phagocytic system (MPS) in mice infected with Trypanosoma brucei was investigated with regard to its possible significance in the aetiology of the immunosuppression characteristic of this disease. in infected mice the spleens and lymph nodes were grossly enlarged, and on histological examination it was shown that the MPS of the liver, lymph nodes, spleen and bone marrow was markedly expanded. Macrophages presented an active appearance and often contained cellular debris. Clearance of intravenously injected sheep red blood cells (SRBC) was increased, in that 1 hour after injection, 2-6 times more 51Cr-labelled SRBC had disappeared from the circulation of infected, compared to uninfected mice; this was due largely to an increased uptake by the expanded phagocytic system of the liver. The intrinsic immunogenic potential of individual macrophages appeared to be unimpaired as judged by the ability of SRBC-containing macrophages from infected mice to elicit a response in syngeneic normal recipient mice. It was concluded that the only evidence that immunosuppression might be associated with an altered activity of the MPS was an increased hepatic uptake of particulate antigen with a relative failure of splenic uptake. Together these might be responsible for a reduction in the concentration of antigen in the tissues of an enlarged spleen below the level necessary to initiate the formation of antibody. [ABSTRACT FROM AUTHOR]

The response of mouse spleen cells to the T cell-independent antigen dinitrophenylated polymer of flagellin (DNP-POL), has been studied using an adoptive transfer system, and compared with the response of bone marrow cells. Spleen cells showed a complex cell dose-response relationship, with a markedly discontinuous curve, for assays performed before day 9 after transfer and antigen challenge. This discontinuity could be explained by a delay in attainment of the peak response for lower cell inocula. The curve became linear on a log-log scale when spleens were harvested on days 9 and 10 post-transfer. Bone marrow cells gave a lower response than would be expected from their lymphocyte content. This response increased progressively with a delay before antigen challenge in the irradiated recipient or in tissue culture prior to cell transfer, suggesting a functional maturation in this cell population, whereas the performance of spleen cells fell off under similar circumstances. The findings were consistent with, but could not prove, the hypothesis that the immediate precursors of anti-DNP antibody-forming cells in bone marrow were high surface immunoglobulin density small lymphocytes that had arisen locally from precursors lacking detectable surface immunoglobulin, by a non-mitotic maturation. [ABSTRACT FROM AUTHOR]

The influence of the route of priming and the dose of sheep red blood cells (SRBC) on the IgM, IgG and IgA-plaque-forming cell (PFC) activity in mouse bone marrow during the secondary response to SRBC was studied. After intraperitoneal and subcutaneous priming the number of IgM, IgG and IgAPFC during the secondary response increased with the number of SRBC used for priming. After intravenous (i.v.) priming the priming dose—secondary response relationship was found to be an optimum curve for IgM-PFC as well as for IgGand IgA-PFC. A peak secondary response in the bone marrow was found after priming with 107 and with 108 SRBC i.v. The appearance of IgG- and IgA-memory cells in the bone marrow after i.v. immunization with SRBC was shown to be dependent on the priming dose: the appearance of IgG-memory cells required a higher dose of SRBC than the appearance of IgM-memory cells, and the appearance of IgA-memory cells required even more antigen.The effect of the booster dose upon the PFC activity was studied in mice primed with 107 SRBC i.v. and boosted with 104, 106, or 109 SRBC i.v. 2 months later. IgM-PFC as well as IgG- and IgA-PFC were present in spleen and bone marrow at each booster dose tested. In each group of mice the PFC activity in the bone marrow rose to a level which surpassed the level in the other lymphoid organs between the 7th and 10th day after the booster injection. Thus, independently of the booster dose, mouse bone marrow is the major source of PFC during the late phase of the secondary response to SRBC. Mice boosted with 109 SRBC i.v. showed a prolonged presence of IgM-, IgG- and IgA-PFC in the thymus. Light and electron microscopic studies revealed the presence of plasma cells and macrophages studded with phagocytosed material in the thymic medulla of these mice, thus providing evidence for a real PFC response within the thymus. A thymic PFC response was absent in mice boosted with either 104 or 106 SRBC i.v. Therefore the thymic PFC activity during the secondary response to SRBC does depend on the booster dose. [ABSTRACT FROM AUTHOR]

When mouse haematopoietic cells are incubated in vitro in appropriate dilutions of horse anti-mouse thymocyte serum or globulin (HAMTS or HAMTG), the number of in vitro colonies formed by such cells is increased. There was a good correlation between the immunosuppressive potency and the colony-enhancing property of a given serum preparation. Correlation between the thymocytotoxicity titre and the colony enhancing property of the sera was poor. For colony enhancement, it was found necessary to have an added source of colony stimulating factor in the medium, whether in the form of mouse serum or human urine. Unlike the effect produced by exposure of bone marrow cells to certain antigens, HAMTG or HAMTS enhanced colonies in the absence of the alpha-globulin component of mouse serum. Thymus-derived immunocompetent cells are not involved in enhancement since this effect was also observed using foetal liver cells. It appears likely that the interaction of an antibody on the surface of some cell or cells involved in vitro colony formation permits a larger fraction of the colony-forming cells to proliferate in vitro. [ABSTRACT FROM AUTHOR]

The time course of the relative distribution of small lymphocytes binding 125I-labelled human thyroglobulin (HTg) in cell suspensions from the peripheral blood and various lymphoid organs was studied in guinea-pigs at progressive intervals up to 28 days after immunization with an emulsion of HTg and BCG in Freund's incomplete adjuvant (FIA). Small lymphocytes binding 125I-labelled HTg were first detected in peripheral blood, popliteal (draining) lymph node, spleen and bone marrow preparations on the 10th day, and in mesenteric (distant) lymph node and thymus preparations on the 14th day after primary immunization. In general, the percentage of these cells increased progressively thereafter until the end of the period of study. Blocking experiments with unlabelled antigens indicated that the binding of 125I-labelled HTg by small lymphocytes was specific. An anti-HTg antibody cytophilic for guinea-pig small lymphocytes was demonstrated by the passive transfer of antigen-binding capacity to lymphocytes of unimmunized animals with hyperimmune guinea-pig serum. It is proposed that, in these experiments, anti-HTg cytophilic antibody was bound first to small lymphocytes in tile tissues participating actively in the immune response (popliteal node, spleen and bone marrow) before spilling over into the general circulation to coat lymphocytes at other sites (mesenteric node and thymus). [ABSTRACT FROM AUTHOR]

Supernatants were obtained from cultures of keyhole limpet haemocyanin (KLH) primed mouse spleen cells, and also from cultures of KLH-educated, thymus-derived lymphocytes (T cells) after re-exposure of cells to the original priming antigen, KLH. These supernatants were able to facilitate the immune response of bone marrow-derived lymphocytes (B cells) to sheep erythrocytes (SRBC). Certain physical and biological properties of such supernatant activities are described. [ABSTRACT FROM AUTHOR]

The changes that take place in the peripheral lymphoid tissues of congenitally athymic nude mice after stimulation with Pneumococcus polysaccharide and after thymus grafting are described. We have found that after antigen stimulation there is an increase in the cellularity of the primary nodules and changes in the endothelial wall of the post-capillary venules suggestive of an increased cell traffic into the lymph nodes. No germinal centres were observed in nude mice subjected or not to deliberate antigen stimulation. After thymus grafting a slow infilling of the thymus-dependent areas by lymphocytes took place, in addition, the presence of germinal centres was noticed. A number of possible explanations for the findings described is put forward and discussed. [ABSTRACT FROM AUTHOR]

Mouse bone marrow as a source of plaque-forming cells (PFC) was studied by single and multiple intravenous injections of sheep erythrocytes (SRBC). In the primary response a great number of PFC appeared in the spleen while only a few showed up in the marrow. In the secondary response there is a clear PFC- response in both the spleen and the bone marrow. The spleen contains the majority of PFC until about 9 days after the second injection. In the course of the reaction, however, the number of PFC in the bone marrow rises to a level which surpasses the level in the spleen. IgM-PFC as well as IgG-PFC and IgA-PFC could be demonstrated in the marrow. In the lymph nodes and Peyer's patches the number of PFC did not increase above the normal background level at any time after the primary or secondary immunization. In order to test whether the bone marrow PFC-response is caused by a migration of PFC from the spleen or by development in situ, mice were splenectomized shortly before the second injection of SRBC. It could be shown that splenectomy does not prevent the bone marrow PFC-response. Because no activity in the other lymphoid organs was observed, it is concluded that the PFC activity of the marrow is caused by development in situ. [ABSTRACT FROM AUTHOR]

Normal human lymphoblasioid cell lines, growing in continuous suspension culture, produce inhibitors of in vitro lymphocyte blastogenesis. The inhibitor reduces human lymphocyte blastogenic responses to phytohaemagglutinin, slreptolysin-O and the mixed lymphocyte culture 90-99%, is non-cytotoxic and can inhibit both newly initiated and on-going responses. The inhibitor is heat-stable at 80°C but labile at 100°C, non-dialysable and degraded by pronase but not DNase or RNase. It is species- and tissue-specific and does not inhibit the proliferation of mouse lymphocytes, human melanoma cells or human bone marrow in vitro colony-forming cells. Inhibitor was produced only under very specific conditions of crowding. Thus, maximal inhibitor production occurred at 5 × 106 lymphocytes per cm" culture surface area while only 0-5%, of the maximal amount was produced at 106 or 5 &tiems; 107 lymphoblasts per cm102. This data is relevant to the nature of feedback control of immunological reactions and may guide the development of new classes of immunosuppressants. [ABSTRACT FROM AUTHOR]

C3H mice immunized with rat erythrocytes developed autoimmune haemolytic anaemia which was very similar to the 'warm-type' autoimmune haemolytic anaemia of man. There was evidence of anaemia, reticulocytosis, shortened survival times of 51Cr-labelled erythrocytes in vivo, and a high incidence of positive direct Coombs' tests. There was no evidence of spherocytosis or of increased susceptibility to osmotically induced lysis. Bone marrow smears showed evidence of erythroid hyperplasia. Splenectomized mice were more severely affected than unsplenectomized mice. In these mice anaemia was more severe, individual positive direct Coombs' tests were stronger: 51Cr-labelled erythrocytes were cleared faster and the compensatory erythroid hyperplasia was less marked. After immunization was stopped both groups of mice quickly became haematologically normal. However, in mice in which immunization was continued, the blood pictures eventually reverted towards normal except for the persistent positive direct Coombs' tests. C57/B1 mice were also susceptible to the disease process but to a much lesser degree than C3H mice. [ABSTRACT FROM AUTHOR]

Splenic PEC dose-response curves were measured in normal mice and in mice of the autoimmune NZB strain for the thymus-independent antigens pneumococcal polysaccharide type 3 (SIII) and bacterial levan. There were differences between the strains in the maximal response achieved to each antigen, but the level at which high dose tolerance occurred was the same in all the strains. The splenic anti-sheep erythrocyte plaque-forming cell dose-response curve of lethally-irradiated, bone marrow restored NZB mice was compared with that of (C57/Bl × BALB,/c)F1, hybrid and (NZB × BALB/c)F1, hybrid mice. Although the dose-response curves of the two hybrid stains were less sharp than that of the NZB, the peak response occurred at the same dose of SRBC (108, i.v.), and reached the same level, tailing off at higher doses, These results indicate that the B cells of NZB mice display normal high-dose tolerance characteristics, at least to these three antigens. [ABSTRACT FROM AUTHOR]

ATP-dependent DNA ligase, which catalyses a covalent repair of phosphodiester breaks induced in DNA by DNAase I, was isolated from chromatin of bone marrow cells of rabbits and purified (more than 400 times against its original state). A major part of the chromatin DNA ligase represents an activated adenylate ligase · AMP complex. [ABSTRACT FROM AUTHOR]

When primed guinea-pig lymph-node cells are incubated in vitro with homologous antigen and 5-bromo-2-deoxy-[³H]uridine, a peak of intermediate density appears between hybrid and normal DNA. This peak does not result from the attachment of a low density substance to DNA, since it is still present in denaturation conditions or after extensive digestion by pronase or phospholipase. By contrast, it disappears after DNA breakage by sonication, indicating that it results from end-to-end joining of labelled and unlabelled DNA segments. [ABSTRACT FROM AUTHOR]

By selective nitration of egg-white lysozyme it is possible to obtain five lysozyme derivatives. Nitration of tyrosine 20 or tyrosine 23 slightly lowers the enzymatic activity and the thermal stability of the protein, modification of tyrosine 53 has a more drastic effect. Lysozyme nitrated on tyrosine 20 or tyrosine 23 loses one antigemc site. These two residues appear to belong to the same antigenic determinant, as lysozyme nitrated on these two tyrosines reacts with the same antibodies than the two former derivatives. Tyrosine 53 belongs to a second antigenic determinant of the enzyme, as it appears from the reaction between trinitrated lysozyme and the antilysozyme antibodies. [ABSTRACT FROM AUTHOR]

Data are presented indicating that the treatment of a monolayer of cells with a neutralized and noninfective mixture of virus and antibody brings about a state of immunity against a fresh dose of identical virus. The phenomenon has to be considered in the interpretation of virus neutralization experiments, as well as in the construction of theories of immunological phenomena. [ABSTRACT FROM AUTHOR]