Stimulation of human T-lymphocyte chemokinesis by arachidonic acid

Effects of Trypanosoma evansi on the output of cells from a lymph node draining the site of Pasteurella haemolytica vaccine administration

The prefemoral efferent lymphatics of sheep infected with Trypanosoma evansi and inoculated with P. haemolytica vaccine and of those given only the vaccine, were surgically cannulated to study the effects of the infection on the total cellular output and output of blast cells from the node in response to the vaccine. T. evansi delayed and depressed the increases in total cell and lymphoblast outputs. In uninfected sheep, the total cellular output increased and peaked at more than twice the prevaccination values on days 4 and 5 after primary vaccination, but the increases were smaller and peaked on days 6 and 8 after primary vaccination in the infected sheep. The output of lymphoblasts mirrored the total cell output, though it was suppressed to a greater degree by T. evansi. The output of blasts peaked at more than 8 and 14 times the prevaccination values in the uninfected animals after primary and secondary (booster) vaccinations, respectively; but in infected animals, it peaked at twice the prevaccination values after the primary vaccination and showed no increase after booster vaccination until 11 days later. It is concluded that the inhibition of total and blast cell outputs by T. evansi may limit the early systemic dissemination of antigen-specific cells, thus playing a role in the induction of immunosuppression by the parasite.

Effect of platelet activating factor (PAF) on the migration of human lymphocytes

BACKGROUND

There is growing evidence to suggest the importance of the lymphocyte in the pathogenesis of asthma, particularly in the late phase reactions and ongoing bronchial hyperreactivity. Platelet activating factor (PAF) has also been identified as a potentially important mediator in asthma.

METHODS

The migration of human peripheral blood lymphocytes obtained from normal volunteers in response to PAF and the effect of PAF antagonists was studied in a well standardised in vitro assay using nitrocellulose micropore filters in a microchemotaxis chamber.

RESULTS

PAF is a potent stimulus to in vitro human lymphocyte migration; at an optimal concentration of 1 nM it augmented lymphocyte chemokinesis to 310% (SE 33%) of control values. The response to PAF appears to be specific since lyso-PAF and other related membrane phospholipids had no effect. PAF-induced migration could be abrogated by specific PAF receptor antagonists such as WEB 2086 (100 nM), and was partially blocked by the cyclooxygenase inhibitor flurbiprofen at a concentration of 1 microM.

CONCLUSIONS

PAF stimulates the in vitro migration of human lymphocytes through a specific PAF receptor. Part of the response may be due to the generation of cyclooxygenase products. PAF may play a part in the recruitment of lymphocytes to asthmatic airways.

Phenotypic analysis of peripheral blood and bronchoalveolar lavage fluid lymphocytes in control and chronic obstructive pulmonary disease affected horses, before and after 'natural (hay and straw) challenges'

Phenotypic analysis of lymphocytes in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) of control and chronic obstructive pulmonary disease (COPD) affected horses, both before and after 'natural (hay and straw) challenge', were performed using immunofluorescent labelling with monoclonal antibodies and flow cytometry. BALF lymphocytes were shown to be predominantly EqCD5+ cells, approximately half of which were also EqCD8+, with a smaller proportion of B cells. In comparison with PB, BALF contained higher proportions of EqCD5+ cells and EqCD8+ cells and a lower proportion of B cells. Horses with asymptomatic COPD had a higher proportion of BALF B cells and a lower proportion of BALF EqCD5+CD8- cells (considered to be predominantly EqCD4+ cells) than controls. Hay and straw challenge increased the ratio of BALF EqCD5+CD8- cells and reduced the ratio of BALF EqCD8+ cells in COPD affected horses, but not in controls. This finding is similar to the pulmonary recruitment of CD4+ cells reported for human asthmatics following allergen challenges.

Regulation of lymphocyte motility by macrophages: characterization of a lymphocyte migration inhibitory factor derived from a macrophage-like cell line

An inhibitory factor on lymphocyte migration was detected using a capillary random migration assay in the culture supernatant of peritoneal exudate macrophages cultured at concentrations greater than 8 x 10(6) cells/ml. After examining different macrophage-like cell lines, J774A.1 cells were found to produce this inhibitory factor, which was termed lymphocyte migration inhibitory factor (LMIF). The inhibitory effect of LMIF on the migration of spleen lymphocytes, thymocytes, and bone marrow cells was determined. The migration of thymocytes was more sensitive to LMIF than was the migration of spleen lymphocytes and bone marrow cells. Interestingly, when the effect of LMIF was tested on the migration of spleen T cells and B cells, T cells were more sensitive than B cells. When the thymocytes were separated by peanut agglutinin into mature and immature thymocytes, the migration of mature thymocytes was more sensitive than that of immature thymocytes, the migration of mature thymocytes was more sensitive than that of immature thymocytes to the effect of LMIF, suggesting that the greatest effect of LMIF was on the migration of mature T cells. Partial purification of LMIF by ion-exchange and gel-filtration chromatography revealed that it is approximately 14,000 in molecular weight and could exist in either monomeric or dimeric forms. The possible role of this factor in an immune response is discussed.

Modulation of lymphocyte motility by beta-endorphin and met-enkephalin

The opioid peptides, beta-endorphin and met-enkephalin, have been shown to affect the immune system, resulting in either enhancement or suppression of immune response. However, the mechanism of the immunomodulatory effects and the immune cells that are affected by the opioid peptides are unclear. Early studies have provided evidence for their influence on granulocytes, monocytes and lymphocytes. In this study, the effect of beta-endorphin and met-enkephalin on the motility of lymphocyte subpopulations was examined. beta-Endorphin, depending on the concentration tested, has only slight enhancing or inhibitory effect on the motility of spleen lymphocytes; interestingly, met-enkephalin inhibited their motility. However, both beta-endorphin and met-enkephalin have a similar effect on the motility of separated spleen T and B lymphocytes, in that the motility of B lymphocytes was enhanced by both opioid peptides whereas the motility of T lymphocytes was inhibited. In contrast to the inhibitory effect of beta-endorphin and met-enkephalin on mature spleen T lymphocytes, the motility of thymocytes was enhanced by both opioid peptides. The results from this study suggest that the interaction of beta-endorphin and met-enkephalin with lymphocytes is complex and intricate.

Rat lymphokines control the migration of nonsensitized lymphocytes

We investigated whether mediators released from rat splenic mononuclear cells could control the in vitro migration of nonsensitized resting rat lymphocytes. Rat splenocytes stimulated with concanavalin A, other mitogens, or histamine release three lymphokines that alter rat lymphocyte migration. A positive chemokinetic factor, termed lymphocyte chemoattractant factor (LCF), has a molecular weight (MW) between 50 and 70 kDa. Two negative chemokinetic lymphokines can also be identified; lymphocyte migration inhibitory factor (LyMIF, MW 25-45 kDa) and a high MW inhibitor (HWMI, MW greater than 70 kDa). Lymphokines were destroyed by heat as well as by treatment with neuraminidase and trypsin. The action of LCF and LyMIF was prevented by phenylmethylsulfonylfluoride, a specific serine esterase inhibitor, and the action of LyMIF was also blocked by alpha-L-fucose. The discovery of these mediators provides the opportunity to study the importance of such chemokinetic lymphokines in animal models of disease.

Modulation of lymphocyte motility by macrophages

Motility of lymphocytes plays a significant role in their functions. Because macrophages frequently associate with lymphocytes in lymphoid tissues and inflammatory sites, they are likely to be important in regulating lymphocyte motility. In this study, we identified a chemokinetic activity in macrophage culture supernatants. Interestingly, this activity could be detected by the capillary migration assay but not by the more commonly used Boyden chamber chemotaxis assay. Colchicine, on the other hand, was chemokinetic for lymphocytes in the Boyden chamber chemotaxis assay but not in the capillary migration assay. Both these observations and previous studies on the morphology of motile lymphocytes on two-dimensional (2-D) surfaces (capillary migration assay) and in 3-D matrices (Boyden chamber chemotaxis assay) suggest that lymphocytes possess more than one motility mechanism--one for 2-D surfaces and one for 3-D matrices. We propose that the macrophage-derived chemokinetic activity described herein only affected the motility mechanism on 2-D surfaces. In addition, we also observed that the chemokinetic activity was produced by "resting" macrophages and could not be augmented by further activation. Finally, the effect was greatest on mature T cells. We propose that this factor plays an important role in facilitating cell interactions within lymphoid tissues and inflammatory sites.

Effects of proglumetacin maleate and its major metabolites on allergic air pouch inflammation in rats

The mechanism of the anti-inflammatory effect of proglumetacin maleate, a novel indomethacin derivative, was examined in vivo in an allergic air pouch inflammation model in rats. Proglumetacin maleate did not affect the volume of pouch exudate 6 h after immunological challenge, irrespective of whether it was administered orally or locally, but it caused dose-dependent inhibition 24 h after challenge. It also caused dose-dependent reduction of leukocyte migration into the pouch exudate both 6 and 24 h after challenge. It markedly decreased the prostaglandin E2 content of the pouch exudate, but tended to increase the leukotriene B4 content. The main metabolites of proglumetacin maleate, desproglumideproglumetacin maleate and indomethacin, had effects similar to those of proglumetacin maleate on these four parameters on an equimolar dose basis. Unlike these three drugs, dexamethasone decreased the leukotriene B4 content of the pouch exudate. These results suggest that the action of proglumetacin maleate is qualitatively the same as that of indomethacin in vivo; that is, it inhibits cyclo-oxygenase in inflammatory sites.

Alteration of lymphocyte functions by 8-methoxypsoralen and longwave ultraviolet radiation. I. Suppressive effects of PUVA on T-lymphocyte migration in vitro

We investigated the influence of 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet radiation (PUVA) on lymphocyte migration in vitro. Nylon wool-purified, mouse splenic T lymphocytes showed locomotive responses to casein, normal mouse serum (NMS), and zymosan-activated mouse serum (ZAS). Migratory responses to casein and NMS, and to ZAS were remarkably suppressed in lymphocytes exposed to 0.5 J/cm2 UVA plus 0.1 micrograms/ml 8-MOP and to 0.8 J/cm2 UVA plus 8-MOP, respectively. The PUVA treatment used in the present study had no effect on random movement and lymphocyte viability. T lymphocytes cultured in the absence of mitogenic agent for 24 h demonstrated a greater increase in their migration activity than noncultured cells, while lymphocytes cultured after 1.0 J/cm2 PUVA pretreatment remained low. These findings suggest that the therapeutic effect of PUVA on inflammatory skin disorders may be due in part to the suppression of lymphocyte migration.

Modulation of human lymphocyte function by C3a and C3a(70-77)

Human C3a and the synthetic octapeptide C3a (70-77), which retains the activities of an anaphylatoxin, inhibit in a concentration-dependent manner the generation of leukocyte inhibitory factor (LIF) activity by human mononuclear leukocytes and T lymphocytes cultured with the mitogens phytohemagglutinin (PHA) or concanavalin A (Con A) or the antigen streptokinase-streptodornase (SK-SD). The generation of LIF activity was inhibited by 50% by 10(-8) M C3a or C3a(70-77) with PHA or Con A as the stimulus, whereas a more than 10-fold higher concentration of C3a(70-77) than C3a was required to achieve the same level of suppression with SK-SD as the stimulus. Similar concentrations of C3a(70-77) inhibited to the same extent the migration of T lymphocytes stimulated by alpha-thioglycerol of Con A. Neither C3a nor C3a(70-77) altered significantly the uptake of [3H]thymidine by human mononuclear cells exposed to PHA, Con A, or SK-SD. The capacity of C3a(70-77)-Sepharose,m but not Sepharose alone, to adsorb or inactivate mononuclear leukocytes required for the generation of LIF activity established a direct interaction. Analysis of the lymphocytes in the effluent from C3a(70-77)-Sepharose columns, using monoclonal antibodies to surface antigens, showed a selective depletion of the helper/inducer population of lymphocytes. C3a might represent an important mediator of the functionally selective regulation of human T lymphocyte activities by the complement system.

Stereospecific chemoattraction of lymphoblastic cells by gradients of lysophosphatidylcholine

Human plasma contains chemoattractant activity for cultured cells from the mouse thymic lymphoma 6C3HED and also for lymphoblasts from concanavalin A-stimulated mouse spleen cells. A major portion of the attractant activity for both cell types could be attributed to plasma lysophosphatidylcholine. Studies on synthetic lysophosphatides showed that polar head group structure, acyl chain length, and stereochemical configuration are important determinants for attractant activity.

Concanavalin A-induced chemiluminescence in rat thymus lymphocytes. Its origin and role in mitogenesis

1. The luminol-dependent chemiluminescence of rat thymocytes responding to concanavalin A can be resolved into glucose-dependent and glucose-independent portions. 2. The glucose-dependent portion, supported by D-glucose and D-mannose oxidation, is inhibited by catalase (200 microgram/ml), amobarbital (1 mM) and hexose analogues that block D-glucose uptake. Thus concanavalin A may activate, transiently, an NAD(P)H oxidase that utilizes reducing equivalents derived from the oxidation of exogenous glucose to give dismutation products of O2- (including H2O2) as its major products. 3. The glucose-independent portion is inhibited by eicosa-5,8,11,14-tetraynoic acid but not by indomethacin. It may therefore be associated with the conversion of hydroperoxy intermediates of arachidonic acid metabolism to hydroxy products by the lipoxygenase pathway. 4. Preincubation of thymocytes for 18 h in serum-free medium enhances the subsequent chemiluminescent response to concanavalin A severalfold and evokes the response at a lower threshold concentration. The incorporation of [3H]thymidine by preincubated cells is similarly enhanced at low doses of concanavalin A, whereas the response to optimal doses is unaltered. 5. Catalase does not inhibit the enhanced incorporation of [3H]thymidine obtained in response to concanavalin A, but instead amplifies the response to low doses in the same manner as preincubation.

Suppression of human lymphocyte migration by PGE2

Prostaglandin (PG) E2 markedly inhibits casein- and C5a-stimulated lymphocyte migration in a concentration-dependent manner. Inhibition is observed with as low as 10(-9) M PGE2 and requires that PGE2 be present during cell locomotion. Studies with PGE1, PGF1 alpha, PGF2 alpha and PGA1 indicate that only PGE1 and PGE2 inhibit lymphocyte migration. These studies indicate that PGE2 may play a role in the regulation of the immune response at the level of lymphocyte locomotion.

The effects of non-steroid anti-inflammatory drugs on leukocyte migration in carrageenin-induced inflammation

Some non-steroid anti-inflammatory drugs which inhibit arachidonate cyclo-oxygenease have been examined for their effects on leukocyte migration, prostaglandin production and oedema formation in carrageenin-induced inflammation in the rat. At doses which inhibited oedema, all the drugs tested caused a dose-dependent reduction in numbers of leukocytes and prostaglandin concentrations in 24-h inflammatory exudates. At lower doses, indomethacin, aspirin, sodium salicylate, flurbiprofen and phenylbutazone significantly potentiated leukocyte migration by 20-70%. Ibuprofen, naproxen and BW755C reversed the indomethacin-induced increase in leukocyte accumulation. BW755C inhibits the generation of chemotactic lipoxygenase products and it is possible that the effects of all these drugs on leukocyte migration are mediated through the lipoxygenase pathway of arachidonic acid metabolism.