PPD-induced immunoglobulin production in human peripheral blood lymphocytes. II. Separation of PPD-reactive helper T cells from PWM-reactive helper T cells in polyclonal immunoglobulin production of human peripheral blood lymphocytes.

We investigated the relationship bewteen PPD-reactive helper T cells and PWM-reactive helper T cells in polyclonal Ig production of human PBL. Elimination of PPD-reactive T cells by BUdR + light treatment resulted in a loss of helper function in PPD-induced Ig production, but had no effect on helper function in PWM-induced Ig production. On the other hand, elimination of PWM-reactive T cells resulted in a loss of helper function in both PPD-induced Ig production and PWM-induced Ig production. A blast cell-enriched fraction that was generated by PPD and separated by the velocity sedimentation method contained helper function in both responses. On the other hand, blast cell-depleted fractions did not contain PPD-reactive helper function, although the PWM-reactive helper function was evident. These results strongly suggest that PPD-reactive helper T cells are included in PWM-reactive helper T cells.     

Stimulation of human peripheral blood lymphocytes by a sodium periodate (NaIO4) induced growth factor

Sodium periodate treated lymphocytes engage in cell to cell interaction and also yield a soluble growth factor that stimulates DNA synthesis when added to naive autologous cells. Adherent cells enhance the factor mediated activity. Sodium periodate stimulated lymphocytes, treated with mitomycin C, produced no growth factor activity. Partial characterization of the factor indicates that it is non-dialyzable, resistant to ribonuclease, and sensitive to heat, trypsin, and papain.     

Subpopulations of human peripheral blood lymphocytes.

Multiple staining protocols have been developed for the classification of subpopulations of human peripheral blood lymphocytes. Of the non-T (E^?) cells, roughly half (10–20% PBL) have receptors for complement components as detected with complement-coated zymosan particles, but do not show Fc receptors as detected with Ripley IgG-coated human RBC. The other half are C^?, Fc⁺, with a small percentage possessing both receptors. The C⁺, Fc^? cells can be subdivided into cells which are IgM⁺ (75%) or IgM^?. Cells with Fc receptors detected with aggregated IgG were IgM⁺.     

Recombinant interleukin-2-induced polyclonal proliferation of in vitro unstimulated human peripheral blood lymphocytes

Human peripheral blood mononuclear cells as well as T-cell-enriched or T-cell-depleted populations were found to proliferate in response to recombinant interleukin-2 (IL-2) in vitro in the absence of a lectin preactivation signal. This proliferative response was detected at Day 2, peaked at Day 5, and was dependent on the concentration of IL-2 used. At the initiation of culture, these cells did not appear to be activated as determined by the expression of Tac antigens. In cultures of unfractionated T-cell-enriched suspensions, high concentrations of IL-2 resulted in preferential expansion of the OKT8+ population, although both OKT4+ and OKT8+ cells proliferated in response to IL-2 when cultured alone. These studies demonstrate that human lymphocytes obtained by standard fractionation procedures from peripheral blood are capable of proliferation in response to IL-2 without in vitro preactivation signals given by the addition of mitogens or antigens to cultures. These findings suggest that in vivo IL-2, in the absence of other exogenous stimuli, may directly influence immune responses and thus may have a potential role as a clinical immunopharmacologic agent.     

Detection of 6-thioguanine resistance in human peripheral blood lymphocytes (PBL) of industrial workers and lung cancer patients

Human peripheral blood lymphocytes (PBL) were selected for 6-thioguanine (6-TG) resistance in short-term (42-h) cultures in 110 high-cancer-risk industrial workers, 131 primary lung cancer patients and 96 low-risk controls. The lymphocytes were cultured and stimulated by phytohemagglutinin (PHA). A labeling index (LI) was scored using light microscope autoradiography, based on the lymphocyte's ability to incorporate tritiated thymidine with or without selective agent 6-TG. The number of 6-TG-resistant cells increased in the high-occupational-cancer-risk group of vinyl chloride- and mixed organic industrial dust (MOID)-exposed workers as well as in primary lung cancer patients. The results were compared with the low-occupational-cancer-risk groups and with samples taken from the 70 healthy individuals and 26 hospitalized, non-cancerous controls. In both risk-exposed groups the frequency of 6-TG-resistant lymphocytes was significantly higher (P < 0.01) than in the controls. These results suggest that the original Strauss and Albertini (1977, 1979) method can be used to study qualitative risk assessment in carcinogen- or mutagen-exposed occupational groups.     

Targeted cytotoxic cells in human peripheral blood lymphocytes.

We have isolated subsets of cells from human PBL and have investigated their abilities to mediate lysis targeted by bispecific antibodies. Targeted cytotoxic cells were divided into two distinct types based on buoyant density. The low buoyant density fraction contained all of the targetable cytotoxic activity in unstimulated PBL, including both T and K cells targeted with anti-CD3 and anti-Fc gamma RIII (CD16) containing bispecific antibodies, respectively. Both types of targetable cytotoxic cells required IL-2 for maintenance of cytotoxic activity, expressed the CD56 (NKH1) marker, and mediated MHC-unrestricted lysis. The targetable T cells in low density PBL were exclusively CD8+ and represented only about 2% of the total PBL. The high buoyant density lymphocytes, depleted of NK cells, had no targetable activity, but were able to generate over several days, targetable T cell activity in the presence of a TCR cross-linking signal plus IL-2. Unlike the low-density cells, the activated high buoyant density effector T cells did not express CD56, consisted of both CD4+ and CD8+ cells, and did not mediate MHC-unrestricted lysis. These cells proliferated more rapidly and generated more total lytic activity than the low-density fraction. Our studies show that targetable cytotoxic activity in human PBL is mediated by several subsets of cells with different activation requirements. Presumably all of these activities could be directed against unwanted cells in clinical or preclinical studies involving targeted cytotoxic cells.     

Lectin-dependent cytotoxicity of human peripheral blood lymphocytes

The evaluative technique of lymphocyte cytolytic activity in human peripheral blood has been designed. The target cells, lectin (Con A) concentration and incubation time for measuring cytolytic activity of lymphocytes pre-purified from adherent cells have been selected. The mean values of lectin-dependent cytotoxicity in peripheral blood of 50 healthy donors are presented.     

Immunoglobulin properties of Epstein-Barr virus transformed human umbilical cord and adult peripheral blood lymphocytes

We have observed that a subset of E+ cells bind human monomeric IgG (FcR-IgG). In the present study, we have separated the E+, FcR-IgG+ cells by flow cytometry and tested their NK activity against the tumor KS62 using the chromium-release assay. Virtually all the NK activity residing within the E+ subset was mediated by E+, FcR-IgG+ cells. These findings are discussed in relation to the cellular lineage of the human NK cell.     

Comparative intracellular cytokine production by in vitro stimulated T lymphocytes from human umbilical cord blood (HUCB) and adult peripheral blood (APB).

To date over 400 HUCB transplants have been reported from different centers. It has been suggested that there is a reduced graft-versus-host-disease (GVHD) with HUCB compared to bone marrow transplantation. Since cytokine production by a cell is an indication of the cells function it is important to determinate the differences between APB and HUCB with respect to production of these soluble factors. Our aim was to analyse the intracellular cytokine production by HUCB and APB T lymphocytes with and emphasize on their possible role in GVHD. Heparinized HUCB samples from 8 normal full-term deliveries and 10 normal blood donors were stimulated 4 hours at 37 degrees C and 5% CO2 with phorbol 12-myristate 13-acetate (PMA) and lonomycin in the presence of brefeldine. Afterwards cells were stained with CD3, CD4 or CD8 in different combinations. Finally, after cell permeabilization, cells were stained with Il-2, Il-4 or IFN-gamma. Data acquisition was performed on a FACScan flow cytometer. Compared to APB, HUCB T lymphocytes produced less Il-2, Il-4 and IFN-gamma. In HUCB, Il-2, Il-4 and IFN-gamma were produced predominantly by CD4+ T cells. In APB, Il-2 and Il-4 were also produced predominantly by CD4+ cells compared with CD8+ T lymphocytes, however, IFN-gamma was produced by both CD4+ and CD8+ T cells. These results indicate that there are clear differences in the cytokine profile between T cells in APB and HUCB.     

Activation of human B lymphocytes. IV. Regulatory effects of corticosteroids on the triggering signal in the plaque-forming cell response of human peripheral blood B lymphocytes to polyclonal activation.

In vitro hydrocortisone in physiologic and pharmacologically attainable concentrations caused a marked enhancement of the PWM-induced PFC response of normal human peripheral blood B lymphocytes. This effect was seen only when hydrocortisone was added within the first 24 hr of culture and only when hydrocortisone and PWM were present together in cultures. Only suprapharmacologic concentrations of hydrocortisone (10(-3) M) were capable of suppressing early B cell activation. Late stages of antibody production and secretion were resistant to suppression by even these extraordinarily high concentrations. Hydrocortisone did not replace the T cell requirement of PWM-induced PFC responses. A single dose of in vivo hydrocortisone (400 mg) to normal adult volunteers did not produce this enhancing effect when PFC responses were measured in vitro in the absence of hydrocortisone. The data strongly suggest that the enhancing effect of hydrocortisone was due not to elimination of naturally occurring suppressor cells, but to a modulation of the triggering signal either directly on the B cell itself or via the balance of positive and negative T cell regulation of B cell activation.     

Platelet-derived growth factor is not chemotactic for human peripheral blood monocytes

PDGF is a mitogenic protein stored in platelets and released upon platelet degranulation. Recent evidence indicates that PDGF plays an important role in both physiologic and pathophysiologic processes, particularly in tumorigenesis, wound healing, pulmonary fibrosis, and atherogenesis. In addition to its mitogenic potential, it has been reported that PDGF stimulates monocyte chemotaxis. Since the recruitment of monocytes from the peripheral vasculature is an important event in vivo, the potential role of PDGF as a monocyte chemoattractant has significant biologic implications. However, we now report that homogeneous human PDGF from platelets and a recombinant PDGF-2 homodimer do not stimulate monocyte chemotaxis. In contrast to previous reports these results indicate that PDGF is not a monocyte chemoattractant.     

Glucocorticoid receptors in purified subpopulations of human peripheral blood lymphocytes.

On the premise that the differential effects of glucocorticoids on various aspects of the immune response may be mediated by differences in the glucocorticoid receptors in the effector cells, subpopulations of human peripheral blood lymphocytes were examined for these receptors as well as for glucocorticoid responsiveness. Purified T and non-T lymphocytes, when studied by a sensitive whole cell assay technique, contained equivalent amounts of specific glucocorticoid receptor, which, by binding affinity and specificity measurements, were indistinguishable from each other. Furthermore, under in vitro incubation conditions, macromolecular synthesis in both of these cell populations was inhibited by glucocorticoid at concentrations which saturated the receptor sites. It is concluded that the putative differential effects of glucocorticoids on T and non-T lymphocyte-associated functions are probably not mediated by differences in the glucocorticoid receptors in these cell populations.     

Shared idiotypes of human peripheral blood B and T lymphocytes.

In a patient with an IgG lambda monoclonal serum component possessing anti-streptolysin O activity, we have demonstrated peripheral blood B and T lymphocytes with shared or similar idiotypes. The idiotypic T lymphocyte membrane structure was capable of binding the specific antigen (SLO). After radioiodination and subsequent detergent solubilization of the same T cell population, immunoprecipitation of the lysate by employing anti-idiotypic antibodies, resulted in the isolation of a polypeptide chain with a m.w. of 70,000 on SDS polyacrylamide gels under reducing conditions. The polypeptide expressed no isotypic immunoglobulin markers. Internal labeling experiments indicated that this membrane structure was actively synthesized by the T lymphocytes.     

Genotoxicity of pemetrexed in human peripheral blood lymphocytes

Pemetrexed (PMX) is an antineoplastic antifolate used in the treatment of non-small cell lung cancer, mesothelioma and several types of neoplasms. Its toxicity in tumor cells has been linked with the potent inhibition of thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase, and subsequent depletion of both purine and pyrimidine nucleotides. However, cytogenetic toxicity of PMX in non-diseased cells has not been adequately studied; despite the increasing data on the DNA-damaging potential of antineoplastic agents on normal cells. In the present study, the genotoxic potential of PMX was evaluated in peripheral blood lymphocytes obtained from healthy human subjects using chromosome aberration (CA), sister chromatid exchange (SCE) and micronucleus (MN) assays as the cytogenetic damage markers. Human peripheral blood lymphocytes were exposed to four different concentrations (25, 50, 75 and 100 μg/mL) of PMX for 24- and 48-h treatment periods. PMX significantly increased the formation of CA in 24-h treatment, but not in 48-h treatment. PMX did not increase the mean SCE frequency in 24- and 48-h treatment periods; however, there was a striking increase (although not statistically significant, p > 0.05) in the number of SCEs at 25 μg/mL (24- and 48-h treatment) and 50 μg/mL (24-h treatment) due to an increase of SCE at the single-cell level. Interestingly, PMX did not induce MN formation in either 24- or 48-h treatment periods. PMX strongly decreased the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) in 24- and 48-h treatment periods. Our results suggest that PMX has a potent cytotoxic effect against human peripheral blood lymphocytes at concentrations which are reached in vivo in the blood plasma.