Tuberculin response of lymphocytes from human skin test nonreactors; evidence for in vitro primary sensitization of T lymphocytes.

Tuberculin-purified protein derivative (PPD) is a B-lymphocyte mitogen in a variety of experimental animals. Although peripheral blood mononuclear cells (PB MNC) from healthy human tuberculin responders consistently responded to PPD by increased incorporation of [³H]thymidine, cell fractionation studies showed this to be due to T-lymphocyte rather than B-cell blastogenesis. Moreover, utilizing thymidine suicide experiments, the T-lymphocyte response could be categorized as antigenic rather than nonspecific mitogenic reactivity. Kinetic studies revealed a delayed peak of PPD-induced thymidine incorporation in PB MNC from tuberculin skin test-negative as compared to skin test-positive donors. This suggested in vitro primary sensitization of T lymphocytes to PPD, which was corroborated in experiments demonstrating tuberculin reactivity of human umbilical-cord blood lymphocytes.     

Allergy to insect stings. IV. Diagnosis by radioallergosorbent test (R.A.S.T.)

Radioallergosorbent tests (RAST(s)) have been developed and assessed for the diagnosis of insect hypersensitivity by using a purified allergen from honeybee venom, phospholipase A, and crude yellow jacket venom. Sera from 193 patients positive both by history and skin test to one of these insects were compared with various groups of control sera. Eighty percent of sera from skin test-positive patients were RAST positive; positive RAST were found in 16% of sera tested from skin test-negative patients. A highly positive RAST correlates well with a positive skin test and clinical sensitivity, but serum IgE is not measurable in many patients with mast cell or basophil bound antibody. Since biologically important reactions of antigen with IgE require that the antibody be cell bound, skin testing would be preferred to RAST if one were limited to a single test for the diagnosis of insect allergy.     

Cellular immunity to Coccidioides immitis: In vitro lymphocyte response to spherules,arthrospores, and endospores

In vitro stimulation of incorporation of tritiated thymidine by human peripheral lymphocytes in response to two soluble antigens and three different intact but nonviable fungal forms of Coccidioides immitis was studied. Lymphocytes were obtained from three groups of subjects: healthy skin test positive, healthy skin test negative, and disseminated disease. Dose-response relationships to the intact forms (endospores, arthrospores, and spherules) were determined. Responses of lymphocytes from healthy skin test-positive subjects and subjects with disseminated disease were similar. Ranking of antigens by “potency” gave the following results: endospores = spherulin > mycelial filtrate > arthrospores = spherules. Endospores were the most potent of the intact forms in 10 of 11 subjects. The clear superiority of endospores over spherules is not due to differences in the total particle surface area available for presentation to the leukocytes. All antigens tested except spherules could discriminate between skin test-positive and skin test-negative subjects in this in vitro system. A T-cell-enriched, B-cell- and mono-cyte-depleted cell population demonstrated an active response to spherulin and to endospores. The variance of these finding with animal studies demonstrating spherules to be immunogenically superior when compared to endospores is discussed. This may have importance in future studies in humans of vaccines to C. immitis.     

Induction of premature chromosome condensation by a phosphatase inhibitor and a protein kinase in unstimulated human peripheral blood lymphocytes: a simple and rapid technique to study chromosome aberrations using specific whole-chromosome DNA hybridization probes for biological dosimetry

We developed a simple and rapid method to study chromosome aberrations involving specific chromosomes using unstimulated human peripheral blood lymphocytes (HPBL). Premature chromosome condensation (PCC) was induced by incubating unstimulated HPBL in the presence of okadaic acid (OA, a phosphatase inhibitor), adenosine triphosphate (ATP), and p34(cdc2)/cyclin B kinase [an essential component of mitosis-promoting factor (MPF)], which eliminated the need for fusion with mitotic cells. OA concentration and duration of incubation for PCC induction was optimized using mitogen-stimulated HPBL; a final concentration of 0.75 microM incubated for 3 h was optimum, resulting in approximately 20% PCC yield. In unstimulated HPBL, PCC was induced by the addition of p34(cdc2)/cyclin B kinase at concentrations as low as 5 units/ml to a cell culture medium containing OA. Increases in the concentration of p34(cdc2)/cyclin B kinase from 5 to 50 units/ml resulted in a concentration-dependent increase in PCC yield (30% to 42%). We demonstrate that this technique of inducing PCC in unstimulated HPBL is suitable for studying radiation-induced aberrations involving a specific chromosome (chromosome 1) after 24 h repair using a whole-chromosome in situ hybridization probe and chromosome painting. Cells with aberrant chromosome number 1 are characterized with more than two chromosome spots. The frequency of cells with aberrant chromosome 1 increased with 60Co gamma-radiation doses in the region 0-7.5 Gy. The observed dose-effect relationship for the percentage of cells with aberrant chromosome 1 (Y) was explained by using both a linear [Y=(2.77+/-0.230)D+0.90+/-0.431, r(2)=0.966] and a nonlinear power [Y=(5.70+/-0.46)D((0.61+/-0.05)), r(2)=0.9901) model. This technique can be applied to biological dosimetry of radiation exposures involving uniform whole-body low linear energy transfer (LET) exposures.     

Specific activation of human T lymphocytes by Robinia pseudoacacia seeds' lectin.

Human peripheral blood and tonsil lymphocytes were fractionated into T and B cells by centrifugation after rosetting with native sheep erythrocytes and tested with Robinia pseudoacacia lectin. The purity of B- and T-enriched populations was checked by E-rosette formation or heterologous antisera specific for B or T lymphocytes. The proliferative response of T cells to Robinia lectin from all the donors tested was not found to differ from that of unfractionated cells, whereas no response of highly purified B cells could be observed to the lectin even with different concentrations of the lectin and different culture periods. B cells, however, were found to bind as much ³H labeled Robinia lectin as unfractionated lymphocytes. In addition, treatment of cells by antihuman T-lymphocyte antigen (HTLA) serum and complement before addition of Robinia lectin completely abolished their response, whereas similar treatment by antihuman B lymphocyte and monocyte antigen (HBLMA) serum did not prevent the T cells from incorporating thymidine. The Robinia lectin, like the other phytomitogens, thus appears to be a specific T-cell activator.     

The effect of hyposensitization on alternaria-induced lymphocyte blastogenesis

Twenty-one atopic children were treated with alternaria hyposensitization therapy. Leukocytes from these children were cultured with and without alternaria and phytohemagglutinin prior to treatment, and after 6 and 12 months of treatment. Patients demonstrating positive immediate cutaneous hypersensitivity showed significant lymphocyte transformation prior to hyposensitization whereas the skin test-negative patients did not. The skin test-negative patients developed significant lymphocyte transformation after 6 months of hyposensitization. Twelve months after the initiation of therapy both skin test-negative and skin test-positive patients showed a decreased lymphocyte reactivity, and there was no longer any significant change in the concomitant phytohemagglutinin responses indicating that hyposensitization had a specific effect on alternaria-induced in vitro lymphocyte reactivity. Plasma factors were found to have modulating effects on the lymphocyte reactivity of hyposensitized patients.     

Studies on the relationship between cell proliferation and cell death: opposite patterns of SGP-2 and ornithine decarboxylase mRNA accumulation in PHA-stimulated human lymphocytes.

To assess the relationship between cell proliferation and cell death, the mRNA accumulation of ornithine decarboxylase (ODC) and sulfated glycoprotein 2 (SGP-2) were measured in human peripheral blood lymphocytes (HPBL) 2-6 hours after stimulation with phytohemagglutinin (PHA). ODC is the rate limiting enzyme of polyamines biosynthesis and its early induction in mitogen-stimulated lymphocytes has been reported. On the other hand, SGP-2, a glycoprotein present in most mammalian tissues, is induced in classical models of apoptosis, such as dexamethasone-treated thymocytes. Indeed, a consistent amount of SGP-2 mRNA in quiescent HPBL, an early and progressive decrease of SGP-2 mRNA and a parallel increase of ODC mRNA accumulation, were observed, in PHA-stimulated HPBL, suggesting that concomitant repression of SGP-2 and induction of ODC genes contribute for the cell entering the cell cycle.     

Leukocyte procoagulant activity in man: an in vitro correlate of delayed-type hypersensitivity

Human mononuclear leukocytes generate cell-bound procoagulant activity (LPCA) after incubation with an antigen (mumps or tuberculin) to which the donor was previously sensitized. An inhibitor of coagulation appears to be liberated into the extracellular culture fluid during incubation of leukocytes with the sensitizing antigen. Removal of this activity before measuring LPCA resulted in a reliable test that correlated directly with delayed skin reactivity. The assay was particularly sensitive in that cells from weakly sensitized donors who reacted only to high doses of tuberculin (100 TU) in the delayed skin tests produced detectable LPCA in vitro. By contrast cells from weakly sensitized donors did not react to PPD in the lymphocyte blast transformation test or the direct macrophage migration inhibition factor test. The LPCA assay correlated closely with the blast transformation and MIF tests in which cells were used from more strongly sensitized donors who reacted in skin tests with lower doses of tuberculin (1 or 10 TU). The assays were antigen-specific in that cells from donors sensitive to mumps antigen but not to tuberculin reacted only to mumps antigen in vitro. The assay was extremely reproducible; cells from individual donors reacted to the same extent over a period of 8 mo). We propose that the assay system reported here represents an improved method for the measurement of cell-mediated immunity in vitro because it requires fewer donor cells, is technically simpler, and is more sensitive than previously described methods.     

Activity and Properties of Macrophage Migration Inhibitory Factor produced by Mixed Lymphocyte Cultures

THE macrophage migration test is an in vitro demonstration of delayed hypersensitivity. Supernatant fluids of sensitive lymphocytes cultured for 24 h in the presence of specific antigen contain migration inhibitory factor (MIF) that arrests the migration of macrophages of unsensitized animals in vitro¹,². In vivo, it induces delayed skin reactions³. The use of the macrophage migration test, based on differences of transplantation antigens in donor and recipient, to show histocompatibility has been suggested⁴. The test was also recommended as an indicator of immunological reactivity after organ transplantation, to demonstrate impending rejection⁵. It can demonstrate homograft sensitivity, for migration of peritoneal exudate cells (containing lymphocytes and macrophages) of CBA mice previously sensitized by grafts from A/Jax donors was inhibited when they were mixed with peritoneal exudate cells of the donor strain. However, histocompatibility was not demonstrated, for mixtures of peritoneal exudate cells of ungrafted CBA mice and A/Jax mice migrated regularly during the 24 h test⁶.     

Age-dependent decline in rejoining of X-ray-induced DNA double-strand breaks in normal human lymphocytes

Unstimulated human peripheral blood lymphocytes (HPBL), separated by density centrifugation from anticoagulated whole blood, were X-irradiated (30 Gy) on ice and incubated in medium at 37 degrees C for repair times of 15, 30, and 120 min. Blood donors were 18 normotensive, non-smoking Caucasians aged 23-78, free from overt pathology and not taking any medications. Neutral filter elution was used to assay DNA double-strand break (DSB) induction and completeness of DSB rejoining (plus rejoining of any X-ray-induced alkali-labile sites converted to DSBs in vitro at pH 9.6). After 30 or 120 min repair incubation, the percentage of DSBs rejoined by cells from older donors (aged 66-78 years) was less than half the percentage of DSBs rejoined by cells from younger donors (aged 23-39 and 42-57). When data from the 3 age groups were pooled, the age-related decline in percent DSBs rejoined was significant for repair times 30 min (r = -0.63, p less than 0.005) and 120 min (r = -0.64, p less than 0.005) but not for 15 min (r = -0.04). These age-related declines were observed even though DNA from older donors sustained fewer strand breaks as demonstrated by the negative correlation between donor age and DSB induction (r = -0.65, p less than 0.005). These results suggest that the efficacy of X-ray-induced DSB repair diminishes with in vivo age in unstimulated HPBL.     

Proliferation of murine thymic lymphocytes in vitro is mediated by the concanavalin A-induced release of a lymphokine (costimulator).

Mitogen-induced proliferation of lymphocytes may in theory result directly from the interaction of mitogen with the cells, or indirectly as a result of the mitogen-stimulated release of lymphokines. In the case of murine thymic lymphocytes exposed to concanavalin A (Con A) in tissue culture, we have determined that mitogenesis depends upon a lymphokine. Interaction of the thymic lymphocytes with lectin is necessary, but not sufficient, for mitogenesis. A lymphokine, or costimulator for mitogenesis, is released by normal spleen or thymus cells during the first 16 hr of their exposure to Con A, and in the presence of a phytomitogen it stimulates thymic mitogenesis. Under conditions of low costimulator levels, no mitogenesis follows the interaction of Con A with cells. The response of adult CBA/J mouse thymocytes to phytohemagglutinin (PHA) is very low, compared to their response to Con A. When costimulator is added to PHA, the cells respond as well as they do to Con A. Costimulator does not act through Con A-binding sites on thymus cells. Its production is dependent on both cells carrying omega surface antigen (T lymphocytes) and adherent cells of the macrophage-monocyte series. The adherent population, but not the T cells, may be heavily irradiated without affecting production of costimulator. Costimulator is not a mitogen on its own.     

Estimation of the relative sensitivity of the comparative tuberculin skin test in tuberculous cattle herds subjected to depopulation

Bovine tuberculosis (bTB) is one of the most serious economic animal health problems affecting the cattle industry in Great Britain (GB), with incidence in cattle herds increasing since the mid-1980s. The single intradermal comparative cervical tuberculin (SICCT) test is the primary screening test in the bTB surveillance and control programme in GB and Ireland. The sensitivity (ability to detect infected cattle) of this test is central to the efficacy of the current testing regime, but most previous studies that have estimated test sensitivity (relative to the number of slaughtered cattle with visible lesions [VL] and/or positive culture results) lacked post-mortem data for SICCT test-negative cattle. The slaughter of entire herds ("whole herd slaughters" or "depopulations") that are infected by bTB are occasionally conducted in GB as a last-resort control measure to resolve intractable bTB herd breakdowns. These provide additional post-mortem data for SICCT test-negative cattle, allowing a rare opportunity to calculate the animal-level sensitivity of the test relative to the total number of SICCT test-positive and negative VL animals identified post-mortem (rSe). In this study, data were analysed from 16 whole herd slaughters (748 SICCT test-positive and 1031 SICCT test-negative cattle) conducted in GB between 1988 and 2010, using a Bayesian hierarchical model. The overall rSe estimate of the SICCT test at the severe interpretation was 85% (95% credible interval [CI]: 78-91%), and at standard interpretation was 81% (95% CI: 70-89%). These estimates are more robust than those previously reported in GB due to inclusion of post-mortem data from SICCT test-negative cattle.     

Culture conditions affecting induction and release of lymphocyte produced proliferation inhibitory factor (PIF)

Studies on the factors affecting the production of a proliferation inhibitory factor (PIF) by human lymphocytes are presented. Maximal PIF production occurred with mitogen stimulation of blood lymphocytes cultured at 1 × 10⁶/ml. Optimal cultures contained 10% fetal calf serum, but PIF could be produced in the absence of serum, and after only a 6-hr pulse exposure to PHA. PIF production was found to correlate with lymphocyte activation in response to the mitogen PHA but was not related to lymphocyte proliferation (DNA synthesis). Inhibitory activity could be detected as early as 3 hr after mitogen addition, long before DNA synthesis occurs. The mitogens Con A and PWM initiated different intensities of DNA synthesis in these cultures, but similar quantities of PIF. Antigenic stimulation of sensitive human peripheral lymphocyte populations resulted in the release of PIF. Cells from donors that gave a strong positive skin test to tuberculin (PPD) responded in tissue culture to PPD by producing PIF, while the cells from skin test negative donors did not. A small quantity of PIF was also evident in the supernatants from cultures with no known stimulus (“unstimulated”), this was found to result from activation of the lymphocytes by nonlymphoid elements and by fetal calf serum. An investigation of the PIF-producing capabilities of other lymphoid tissues showed that lymph node cells produced this humoral factor, whereas thymus cells did not. Thymus cell supernatants, in fact, were found to contain an extremely labile cytotoxin which degraded rapidly upon storage.     

Cellular requirements for lymphocyte restimulation after a first challenge in vitro.

Human peripheral blood lymphocytes from donors who were sensitized in vivo to bacterial antigens were stimulated by these antigens in vitro. When the cells from these first cultures were challenged with irradiated allogeneic lymphocytes, a proliferative response was obtained, the kinetics of which resembled those of a primary mixed lymphocyte reaction (MLR). On the other hand, the addition, under these conditions, of bacterial antigens never led to any second proliferative response. It was shown that: (1) the addition of irradiated autologous mononuclear cells, together with the bacterial antigens, led to a reconstitution of a proliferative response in second culture; (2) the cells capable of reconstituting the reactivity to tetanus toxoid could also be obtained from donors whose own cells did not respond to that antigen in primary cultures, and (3) the reconstituting activity in the second culture could not be provided by monocytes alone.     

Nonspecific enhancement of mouse antihapten IgE antibody response: Involvement of a T-cell subpopulation and its product for the potentiation

A concomitant administration of Nippostrongylus brasiliensis saline extract (Nb) with dinitrophenylated ovalbumin (DNP-Ov) significantly enhanced the anti-DNP IgE antibody response in mice which had been irradiated and given a combination of spleen and mesenteric lymph node cells from syngeneic, infected donors and cells from DNP-keyhole limpet hemocyanin (DNP-KLH)-primed donors. The treatment of lymphocytes from infected mice with anti-mouse brain-associated θ serum and C abrogated the enhancing activity. The potentiation occurred in mice receiving nylon wool-nonadherent cells but not in mice receiving adherent cells. Challenge with Nb plus DNP-Ov failed to induce potentiation in C3H mice which are known as nonresponders to low doses of Ov, whereas challenge with Nb plus DNP-bovine gamma globulin (BGG) potentiated the response. However, further increase of the enhanced response was not obtained by adding carrier (BGG or Ov)-primed cells to the transferred lymphocyte populations. When a T-independent antigen, DNP-Ficoll, was used for challenge concomitantly with antigen Nb, no potentiation occurred, even though DNP-Ficoll did not give any tolerogenic or suppressive effect on the IgE antibody response to DNP-Nb. An enhancing activity on the IgE class of antibody response but not on the IgG class was observed in supernatants of in vitro culture of lymphocytes from infected mice upon stimulation of the cells with 10 to 50 μg Nb. These results indicate that the potentiation is mediated by Nb specific T cells via a soluble factor(s) that enhances specifically the IgE class of antibody responses but nonspecifically in terms of antigens used for immunization. The results also suggest that the potentiating factor displays its activity in the presence of other T cells reactive to carrier determinants of the challenging antigen but not of cells which already have committed themselves to the carrier and differentiated as helper cells.     

Primary in vitro generation of cytotoxic cells specific for human minor histocompatibility antigens between HLA-identical siblings

A limiting dilution culture system was developed for the primary in vitro detection of human minor histocompatibility antigens by cytotoxic T lymphocytes (CTL). CTL were generated in primary in vitro culture between two HLA-identical sibling pairs and propagated as stable CTL lines. Population and family studies indicate that these CTL lines recognize minor histocompatibility antigens in an HLA-restricted manner. The antigen recognized by one CTL line is detected on six (out of 37) HLA-B7-positive donors but not on 32 HLA-B7-negative donors. The cytotoxicity of this CTL line is mediated by T3+, T8+ effector cells. The antigen detected by this CTL population is different from all known human minor histocompatibility antigens. The data of this study, like those in the mouse system, suggest that a suppressor cell is diluted out in a limiting dilution culture, which allows the activation of the CTL precursors.     

Induction of antigen-specific antibody response in human peripheral blood lymphocytes in vitro by a dog kidney cell vaccine against rabies virus (DKCV)

In the present report an in vitro method for obtaining a secondary human antibody response to a dog kidney cell vaccine against rabies virus (DKCV) is described. Cultures of peripheral blood mononuclear cells from normal rabies-immune and nonimmune donors were stimulated in vitro by DKCV. The production of virus-specific antibody in supernatant fluids was monitored by ELISA. Antibody was produced by lymphocytes from rabies-immune individuals, whereas those of nonimmune subjects consistently failed to produce anti-rabies antibodies after in vitro stimulation with DKCV. The generation of the anti-rabies virus antibody response of lymphocytes stimulated with DKCV was shown to be an antigen-dependent, as well as an antigen-specific process. Optimal antigen-specific responses were observed at relatively low concentrations of antigen (10(-1) to 10(-2) micrograms/culture). At increasing concentrations of antigen in culture (greater than 1 microgram/culture), the anti-rabies virus response was suppressed. Antibody produced upon stimulation was capable of neutralizing rabies virus. The response to rabies virus requires T cell help because lymphocytes depleted of SE rosetting cells did not respond to an antigenic stimulus. Studies in which the same individuals were followed over time showed a sequential development of circulating B cell subsets. The system may provide a model for the study of human B cell differentiation in vivo and in vitro and may be valuable for testing the potency of rabies vaccines in vitro.     

The alkaline single cell gel electrophoresis assay with mouse multiple organs: results with 30 aromatic amines evaluated by the IARC and U.S. NTP

The genotoxicity of 30 aromatic amines selected from IARC (International Agency for Research on Cancer) groups 1, 2A, 2B and 3 and from the U.S. NTP (National Toxicology Program) carcinogenicity database were evaluated using the alkaline single cell gel electrophoresis (SCG) (Comet) assay in mouse organs. We treated groups of four mice once orally at the maximum tolerated dose (MTD) and sampled stomach, colon, liver, kidney, bladder, lung, brain, and bone marrow 3, 8 and 24 h after treatment. For the 20 aromatic amines that are rodent carcinogens, the assay was positive in at least one organ, suggesting a high predictive ability for the assay. For most of the SCG-positive aromatic amines, the organs exhibiting increased levels of DNA damage were not necessarily the target organs for carcinogenicity. It was rare, in contrast, for the target organs not to show DNA damage. Organ-specific genotoxicity, therefore, is necessary but not sufficient for the prediction of organ-specific carcinogenicity. For the 10 non-carcinogenic aromatic amines (eight were Ames test-positive and two were Ames test-negative), the assay was negative in all organs studied. In the safety evaluation of chemicals, it is important to demonstrate that Ames test-positive agents are not genotoxic in vivo. Chemical carcinogens can be classified as genotoxic (Ames test-positive) and putative non-genotoxic (Ames test-negative) carcinogens. The alkaline SCG assay, which detects DNA lesions, is not suitable for identifying non-genotoxic carcinogens. The present SCG study revealed a high positive response ratio for rodent genotoxic carcinogens and a high negative response ratio for rodent genotoxic non-carcinogens. These results suggest that the alkaline SCG assay can be usefully used to evaluate the in vivo genotoxicity of chemicals in multiple organs, providing for a good assessment of potential carcinogenicity.     

Regulatory Factors of Lymphocyte-Lymphocyte Interaction: I. Con A-Induced Mitogenic Factor Acts on the Late G1 Stage of T-Cell Proliferation

DNA synthesis in murine lymphocytes was augmented by a soluble factor in the supernatant of serum-free cultures of syngeneic spleen cells activated with concanavalin A (Con A). This so-called mitogenic factor (MF), which is probably identical with interleukin II, partially purified by DEAE-cellulose and Sephadex G-75 chromatography, is a fairly homogeneous molecule of 17–25 × 10³ daltons. By using partially purified MF, the role of MF in lymphocyte proliferation was investigated. Pretreatment of lymphocytes with Con A for the first 3 hr of culture, which does not in itself induce cell proliferation, markedly augmented the effect of MF. The presence of MF, however, is necessary only in a restricted stage (s) of lymphocyte proliferation. The addition and removal of MF at various times during culture showed that MF exerts its effect on a process which occurs 3–6 hr before the beginning of DNA synthesis. These results strongly suggest that MF regulates the proliferation of mitogen-stimulated lymphocytes by acting on a restricted stage (s) of the cell cycle.