The role of lymphokines in delayed-type hypersensitivity reactions

Changes in the immune system during and after spaceflight

The results of immunological analyses before, during and after spaceflight, have established the fact that spaceflight can result in a blunting of the immune mechanisms of human crew members and animal test species. There is some evidence that the immune function changes in short-term flights resemble those occurring after acute stress, while the changes during long-term flights resemble those caused by chronic stress. In addition, this blunting of the immune function occurs concomitant with a relative increase in potentially infectious microorganisms in the space cabin environment. This combination of events results in an increased probability of inflight infectious events. The realization of this probability has been shown to be partially negated by the judicious use of a preflight health stabilization program and other operational countermeasures. The continuation of these countermeasures, as well as microbial and immunological monitoring, are recommended for continued spaceflight safety.

An essential role for macrophage migration inhibitory factor in the tuberculin delayed-type hypersensitivity reaction

30 years ago, investigations into the molecular basis of the delayed-type hypersensitivity reaction (DTH) provided evidence for the first lymphokine activity: a lymphocyte-derived mediator called macrophage migration inhibitory factor (MIF), which inhibited the random migration of peritoneal macrophages. Despite the long-standing association of MIF with the DTH reaction and the cloning of a human protein with macrophage migration inhibitory activity, the precise role of MIF in this classic cell-mediated immune response has remained undefined. This situation has been further complicated by the fact that two other cytokines, interferon gamma and IL-4, similarly inhibit macrophage migration and by the identification of mitogenic contaminants in some preparations of cloned human MIF. Using recently developed molecular probes for mouse MIF, we have examined the role of this protein in a classical model of DTH, the tuberculin reaction in mice. Both MIF messenger RNA and protein were expressed prominently in DTH lesions, as assessed by reverse transcription polymerase chain reaction, in situ hybridization, and immunostaining with anti-MIF antibody. The predominant cellular origin of MIF appeared to be the monocyte/macrophage, a cell type identified recently to be a major source of MIF release in vivo. The administration of neutralizing anti-MIF antibodies to mice inhibited significantly the development of DTH, thus affirming the central role of MIF in this classic immunological response.

Induction of urinary interleukin-1 (IL-1), IL-2, IL-6, and tumour necrosis factor during intravesical immunotherapy with bacillus Calmette-Guérin in superficial bladder cancer

To study the local immunological effects of intravesical bacillus Calmette-Guérin (BCG) therapy in superficial bladder cancer patients, the production of interleukin-1 (IL-1), IL-2, IL-6, tumour necrosis factor alpha (TNF alpha), and interferon gamma (IFN gamma) was investigated in the urine. Urine specimens were collected during the six weekly BCG instillations, before instillation, and 2, 4, 6, 8, and 24 h thereafter. Results were standardized to urine creatinine. In general, the concentration of IL-1 increased markedly during the first three BCG instillations, reaching a plateau from instillations 3 to 6. IL-2 was not detected after the first BCG instillation, but from the second instillation onwards the mean IL-2 concentration increased rapidly. With respect to IL-6, patients had relatively high levels in the urine after the first BCG instillation. A relatively moderate increase of the IL-6 concentration was observed during the following weeks. Like IL-2, TNF alpha was only detected after repeated BCG instillations. Generally the highest TNF levels were found after BCG instillation 5. The presence of IFN gamma could not be demonstrated. With respect to the occurrence of the cytokines during the first 24 h after the BCG instillation, TNF, IL-2, and IL-6 were detectable 2 h after the instillation. In contrast, IL-1 seemed to appear later, i.e. from 4 h onwards. TNF decreased most rapidly; it was nearly absent in 6-h samples. Generally IL-2 was not detectable in the 8-h samples, whereas IL-1 and IL-6 were present up to 8 h after instillation of BCG. The presence of TNF was found less frequently than the presence of IL-1, IL-2, and IL-6. Neutralization experiments indicated that most of the IL-1 present in the urine after BCG treatment was IL-1 alpha. In conclusion, activation of BCG-specific T cells was indicated by the detection of IL-2. The presence of IL-1, IL-6, and TNF alpha might suggest activation of macrophages by intravesically administered BCG, although production by other cell types cannot be excluded. It is suggested that these cytokines, in combination with the leucocytes that are known to be recruited to the bladder in reaction to the BCG treatment, may play an important role in the antitumour activity of BCG against bladder cancer. For monitoring purposes, collection of urine might be performed during the first 6 h after BCG instillations 4-6.(ABSTRACT TRUNCATED AT 400 WORDS)

Relapsing encephalomyelitis following transfer of partial immunity to JHM virus

Mice infected with the JHM strain mouse hepatitis virus (JHMV) develop a fatal encephalomyelitis with evidence of demyelination. It has previously been shown that the adoptive transfer of 5 x 10(7) nylon wool adherent (NWA) spleen cells from immunized donors to lethally infected recipients clears virus from the central nervous system (CNS) and prevents demyelination. Adoptive transfer of a smaller number (1 x 10(7] of NWA spleen cells from immunized donors also protects from death but does not significantly alter virus replication in the CNS during the acute phase of the infection. Moreover, these mice develop a transient non-fatal encephalomyelitis which occurs approximately 3 weeks post-infection. This delayed encephalomyelitis is associated with a mononuclear cell infiltration into the CNS but little or no evidence of virus replication or increased viral antigen. A virus-specific delayed-type hypersensitivity (DTH) response precedes this delayed onset of disease by 24 to 48 h. Resolution of disease correlates with a selective and permanent suppression of the JHMV-specific DTH reactivity. In addition, no virus-specific DTH is detected following adoptive transfer of viral-specific DTH effectors derived from immunized donors. In contrast, these mice respond to a heterologous antigen, KLH, suggesting that the resolution of the encephalitis is accompanied by a profound suppression in viral-specific DTH response.

T cell mediated induction of bronchial hyperreactivity

Inadequate reactions of the immune system, i.e. allergic or hypersensitivity reactions, can lead to lung tissue injury. We investigated the relationship of type IV hypersensitivity, as an example of IgE independent hypersensitivity, with the induction of airway hyperreactivity. After antigen challenge (picrylsulphonic acid (PSA] in picrylchloride (PCl) sensitized mice, peribronchial and perivascular accumulation of mononuclear cells was found that was maximal 48 h after challenge. At several time points after challenge, changes in smooth muscle tone of mouse isolated tracheas were measured isometrically. In sensitized mice the response to carbachol was increased, reaching a maximum 48 h after challenge. This hyperreactivity was not found in athymic (nude) mice. We concluded from these data that airway hyperreactivity can be immunologically induced other than by IgE.

The effect of dual inhibitor, SK&F 86002, on helper T cell functions

SK&F 86002, a mixed cyclooxygenase-lipoxygenase inhibitor, was examined for its effects on helper T cell functions. The drug was found to inhibit concanavalin A-induced mitogenesis of splenic T cells (IC50 = 13 microns), the mixed lymphocyte response (IC50 = 16 microM), and proliferation of antigen specific T cells (cloned line, IC50 = 11 microM; uncloned line, IC50 = 13 microM). In contrast, another mixed cycloxygenase-lipoxygenase inhibitor, BW775c, did not have such effects at non-cytotoxic levels. These T cell functions are believed to be dependent on the effects of elaborated IL-1. SK&F 86002 has been shown to inhibit the production of mature IL-1 (IC50 = 1 microM), possibly accounting for the anti-inflammatory effects of the drug in rheumatoid arthritis models. In an in vivo model of contact sensitivity, SK&F 86002 was able to inhibit mouse footpad swelling, demonstrating additional anti-inflammatory activity. As an inhibitor of IL-1 synthesis or release, SK&F 86002 may be useful for the treatment of T cell-dependent inflammation.

Macrophages: current views on their differentiation, structure, and function

Macrophages are large mononuclear phagocytes that represent the major differentiated elements of the mononuclear phagocytic system. They arise from distinct progenitors in the bone marrow, and their immediate precursors, the monocytes, emigrate from the vascular compartment into many tissues and organs where they develop into mature macrophages. The latter display diverse morphological and functional characteristics, depending on the environmental stimuli that they receive. This phenotypic heterogeneity is, therefore, the final consequence of a series of down-regulation of some cellular processes and the up-regulation of others. The kinetics of the production of macrophages and their participation in various physiological and pathological phenomena is the subject of this review.

The rapid induction by interleukin-2 of pulmonary microvascular permeability

The clinical use of interleukin-2 (IL-2) is limited by severe cardiopulmonary dysfunction. This study examines the mechanism of respiratory failure related to IL-2, using sheep with chronic lung lymph fistulae. Awake animals were infused with an intravenous (I.V.) bolus of IL-2 10(5) U/kg (n = 5) or its excipient (EXC) control (n = 3), every 8 hours for 4 to 5 days. Cardiopulmonary function was monitored daily for at least one 8-hour period. Within 2 hours after each IL-2 administration, mean pulmonary arterial pressure (MPAP) rose. On Day 1, the mean rise was from 13 to 26 mmHg (p less than 0.05), and on Day 5, to 29 mmHg (p less than 0.05). MPAP returned to baseline levels after 2-3 hours. Pulmonary arterial wedge pressure was unchanged from 4 mmHg. There were transient falls in arterial oxygen tension, from 88 to 77 mmHg on Day 1 and to 73 mmHg (p less than 0.05) on Day 5. Lung lymph flow (QL) rose from 2.4 to 6.8 ml/30 minutes (p less than 0.05) on Day 1, and from 4.7 to 10.2 ml/30 minutes (p less than 0.05) on Day 5, whereas the lymph/plasma protein ratio increased on Day 1 from 0.69 to 0.83 (p less than 0.05) and from 0.63 to 0.71 (p less than 0.05) on Day 5. This documents an increase in pulmonary microvascular permeability. Thromboxane (Tx)B2 levels increased transiently after each IL-2 injection in plasma from 195 to 340 pg/ml (p less than 0.05) and in lung lymph from 222 to 772 pg/ml (p less than 0.05) on Day 1, and to similar levels on Day 5. There was a progressive rise in cardiac output from 5.7 to 8.6 1/minute (p less than 0.05) during the 5 days of infusion. Systemic blood pressure did not change. Temperature rose from 39.1 to 41.2 C (p less than 0.05), and shaking chills were common. There was a progressive fall in leukocyte count, from 8.4 to 3.2 X 10(3)/mm3 (p less than 0.05) by Day 5, reflecting a 77% fall in lymphocytes. Lung lymph lymphocyte counts rose, and lymphocyte clearance increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined effects of interferon alpha and interleukin 2 on the induction of a vascular leak syndrome in mice

Immunotherapy with interleukin 2 (IL-2) alone or in combination with lymphokine-activated killer cells can mediate tumor regression in mice and in man. Further dose escalation of IL-2 along with lymphokine-activated killer cells has been prevented by the development of a vascular leak syndrome produced by IL-2. Because we have found that interferon alpha (IFN-alpha) or tumor necrosis factor (TNF-alpha) has synergistic antitumor effects when administered together with IL-2, we have tested the vascular leakage induced by these lymphokine combinations. We used a murine model to quantify vascular leakage by measuring the extravasation of 125I-albumin from the intravascular space as well as the wet and dry lung weights after treatment with different cytokines. Cytokines (or Hanks balanced salt solution) were administered to C57BL/6 mice and 4 h after the last injection the vascular leak was quantified. IFN-alpha alone did not cause extravasation of radiolabel or increase in wet lung weights, though when given in combination with IL-2, significantly greater extravasation (P less than 0.01) as well as increase in lung water weights (P less than 0.05) was observed compared to the response in mice treated with IL-2 alone. IFN-alpha in combination with IL-2 induced significant vascular leakage earlier than the response induced by IL-2 alone. For example treatment with IFN-alpha and IL-2 induced accumulation of 14,674 +/- 605 cpm in the lungs at day 1 while IL-2 alone induced 12,340 +/- 251 cpm. The degree of vascular leakage was highly related to the dose of IFN-alpha administered along with IL-2 and increased vascular leak syndrome was evident even at low doses (5000 units) of IFN-alpha. Immunosuppression of mice by pretreatment irradiation (500 rad) markedly decreased the development of vascular leak syndrome induced by IL-2 and IFN-alpha. Interestingly IFN-gamma and TNF-alpha did not induce vascular leakage in the lungs when given alone, and did not add or synergize with IL-2 in causing the syndrome. Thus the administration of IFN-alpha in combination with IL-2 produces a dose-limiting vascular leakage that is more severe than that caused by IL-2 alone, and may be mediated, directly or indirectly by host radiosensitive cells.

Microcirculatory changes in livers of mice infected with murine hepatitis virus. Evidence from microcorrosion casts and measurements of red cell velocity

Hepatitis has been considered, classically, as a diffuse hepatocellular necrosis, and little attention has been paid to the relationship of lesions to the microvasculature. In livers of mice (Balbc/J) infected with murine hepatitis virus (MHV-3), microcorrosion casts showed spherical cavities where casting compound was unable to fill sinusoids. At 48 hr postinfection such "lesions" had a mean diameter of 83 micron +/- 26 (SD) and their number/mm2 (at the surface of casts) was 0.95 +/- 1.3. Blind-ended sinusoids formed a distinct boundary between perfused and nonperfused areas, and concave impressions at their ends indicated cells blocking the lumen. In vivo microscopy of transilluminated livers in infected mice showed localized rounded areas without flow, corresponding to lesions seen in casts. RBC velocity measurements in sinusoids adjacent to lesions demonstrated that velocities fall from normal values to zero over a narrow border zone. Beginning with the most proximal sinusoid with visible flow and moving outward from the lesion to the second and third sinusoids, mean RBC velocities (micron/sec, +/- SD) were 17.4 +/- 6.7, 33.9 +/- 8.7, 66.6 +/- 27.3, respectively; this last value was not significantly different from velocities in normal liver (69.2 +/- 30.6). Transmission electron microscopy of livers of infected mice confirmed the presence of sinusoidal lumens blocked by protruding lining cells, RBCs, platelets, swollen hepatocytes, and cellular debris. This study demonstrates that the lesions are focal in origin, microvascular blockage leading to gradually increasing necrosis in all directions.

Delayed-type hypersensitivity response in the central nervous system during JHM virus infection requires viral specificity for protection

The JHM strain of mouse hepatitis virus (JHMV) elicits an I-A-restricted delayed-type hypersensitivity (DTH) response mediated by a Thy-1+, Lyt-1+, and CD4+ T cell. Adoptive transfer of these polyclonal CD4+ T cells from immunized mice prevents death in lethally infected recipients without significantly reducing virus titer in the central nervous system (CNS). These observations raise the possibility that the recruitment of mononuclear cells into the CNS may play a critical role in survival from a lethal CNS infection. Transient DTH response to nonviral antigens induced an accumulation of monocytes in the CNS that was maximal at 48 h post-challenge and virtually resolved by 5 days post-challenge. By contrast the induction of prolonged DTH responses resulted in the accumulation of a large number of monocytes that persisted in the CNS for at least 5 days post-challenge. Neither type of DTH reaction suppressed virus replication or prevented death from concomitant lethal JHMV infection.

Clinical assessment of host defense

Host defense mechanisms are a determinant of infection. Anergy in surgical patients is a signal of broadly based immune deficits, which include abnormalities in specific and local nonspecific antibacterial defenses and related life-threatening sepsis. Analysis of these abnormalities and other risk factors allows us to generate a long-predictive equation of individual probability of death.

Current trends in research on the etiology and pathogenesis of byssinosis

The features of the cotton dust syndrome which need to be considered when formulating a hypothesis on mechanism(s) are: 1) the presence of fever, 2) the "Monday effect," 3) the slow onset of forced expiratory volume in 1 second (FEV1) changes, and 4) the presence of bronchitis in chronic sufferers but the absence of emphysema or fibrosis. The main hypotheses concerning the mechanisms are direct release of histamine triggered by cotton dust components, immune reactions (principally antibody mediated) to cotton dust antigens, and inflammatory response(s) triggered by endotoxins released from bacterial contaminants on the dust. While histamine release and immune reactions may occur as a result of cotton dust inhalation, it is suggested that they are of secondary importance in comparison to inflammation. Evidence is reviewed that implicates bacterial lipopolysaccharide (LPS) present in the dust as the principal etiologic agent in this process. It is postulated that LPS inhalation stimulates a secretory response by lung macrophages, involving the release of effector molecules which trigger coagulation, bronchoconstriction, fever, and mucus production. LPS-induced macrophage secretory products also promote the local sequestration and activation of both neutrophils and platelets, which serve to amplify the inflammatory response. Evidence is presented implicating both interstitial and alveolar macrophages in this process. The problems associated with the identification of "high risk" groups of cotton workers will be discussed, from a number of viewpoints; consideration will be given to the role of a variety of environmental factors (including tobacco smoking) in this context, as well as possible genetic factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of macrophage procoagulant activity in murine systemic lupus erythematosus

To explore the induction of monocyte/macrophage procoagulant activity in autoimmune disease, the BXSB murine model of systemic lupus erythematosus was studied. Splenic macrophage procoagulant activity rose coincident with age and the development of glomerulonephritis from 38 +/- 6 mU/10(6) macrophages at 1 mo to a maximum of 29,000 +/- 15,000 mU at 4 mo. Macrophages from 1-mo-old mice could be induced to express a 1,000-fold increase in monocyte/macrophage procoagulant activity when incubated with lymphocytes or lymphocyte supernatants from 5-mo-old mice. Plasma from 5-mo-old but not from 1-mo-old mice was able to induce the production of the lymphokine by cells from 1-mo-old animals. This lymphokine was not interleukin 1,2, or gamma interferon. We conclude that induction of monocyte/macrophage procoagulant activity parallels disease development in the male BXSB mouse, is dependent on the interaction between lymphocytes and plasma factors, and may be important in mediation of injury in lupus nephritis.

Measurement of skin swelling in the tuberculin test by ultrasonography

A new method is described for non-invasive measurement of the thickness of the skin at the site of a skin test from the echo pattern of a pulsed ultrasonic (15 MHz) A-mode scanner. In tuberculin tests on normal volunteers, the skin thickness increased rapidly during days 1 and 2 and was usually greatest at day 4. The echogram measurements can be used to calculate the increase in skin volume and this is disproportionately greater than would be expected from measurements of the diameters of erythema and induration.

Generation of procoagulant activity by mononuclear phagocytes: optimisation of an in vitro assay

Leucocyte procoagulant activity (PCA) has previously been advocated as a useful measurement of cell-mediated immune reactivity. The assay is, however, susceptible to inter- and intra-experimental variation. This investigation identifies several factors which influence the stability and reproducibility of the test. Major factors which affect the recalcification time of plasma, include plasma lability, medium/buffer pH and both the nature and concentration of the indicator cells used in the assay. C. parvum-induced mouse peritoneal exudate cells have been used as a novel source of mononuclear phagocytes in the generation of PCA. Their sensitivity as indicator cells has been demonstrated by their responsiveness to stimulation by phytomitogen, endotoxin, and lymphokine (macrophage procoagulant-inducing factor). A simple test based on antigen-induced PCA of these cells, has provided an in vitro index of in vivo sensitisation to sheep red blood cells. Optimisation and standardisation of conditions detailed in this report for estimating PCA, renders the assay of value in monitoring lymphocyte and macrophage activation.

Acute and chronic changes in the microcirculation of the liver in inbred strains of mice following infection with mouse hepatitis virus type 3

The acute and chronic effects of mouse hepatitis virus type 3 on the microcirculation of the liver in both semisusceptible C3HeB/FeJ and fully resistant A/J mice were studied. In the C3HeB/FeJ mice, abnormalities of microcirculatory flow were noted as early as 12 hr after infection and by 24 hr, localized avascular foci appeared. Disturbances were characterized by granular blood flow, sinusoidal microthrombi, distortion of sinusoids by edematous hepatocytes and necrotic lesions. Following the acute infection, Day 10, two patterns of chronic disease were observed. Eighty percent of the mice developed chronic granulomatous hepatitis whereas in the remaining 20% a more severe chronic aggressive hepatitis was observed which was characterized by ongoing hepatocellular necrosis and a marked mononuclear cell infiltrate. In both cases, in vivo microcirculatory abnormalities were found predominantly around visible lesions. Onset of the microcirculatory abnormalities was found to be concomitant with a rise in monocyte related procoagulant activity. Procoagulant activity rose acutely and remained elevated throughout the chronic phase but was higher in animals with severe disease. In contrast to the above, normal blood flow and histology were seen in the resistant A/J mice at all times following infection, and procoagulant activity remained at basal levels despite active viral replication as demonstrated by immunofluorescence studies and recovery of infectious virus. These observations suggest a role for monocyte procoagulant activity in the development of microcirculatory abnormalities following mouse hepatitis virus type 3 infection which may be important in the pathogenesis of the disease.