[Interleukins as highly informative markers of the activity of the inflammatory process of the adnexa uteri]. / Interleikiny--vysokoinformatyvni markery aktyvnosti zapal'noho protsesu v prydatkakh matky.

Interleukins are highly informatively markers of the activity of the inflammatory process in the uterine appendages. Interleukin-6 and tumornecrotic factor allow to diagnose chronic inflammation in uterine appendages without clinical manifestation.

Cytokine modulation of the immunosuppressive phenotype of pulmonary alveolar macrophage populations.

Under steady-state conditions, T-cell activation in the lung is tightly controlled by lymphocytostatic signals from resident pulmonary alveolar macrophages (PAM). The present study focuses upon the mechanism of suppression in the mouse, and how it is bypassed during local inflammatory challenge. Reactive nitrogen intermediates such as nitric oxide (NO) are shown to play a central role in the process as the expression of lymphocytostatic activity by resident murine PAM was abrogated by the NO synthetase inhibitor N-monomethyl-arginine. Overnight pretreatment of resident PAM with granulocyte-macrophage colony-stimulating factor (GM-CSF) abrogated lymphocytostatic activity, with a concomitant small decrease in NO production; this effect was markedly amplified by tumour necrosis factor-alpha (TNF-alpha), but the latter was ineffective alone. The cytokines were inactive if added singly or in combination to fresh PAM:T-cell co-cultures. If GM-CSF plus TNF-alpha exposure of PAM was prolonged beyond 48 hr, both lymphocytostatic and NO-producing capacity were spontaneously re-established. Transforming growth factor-beta (TGF-beta) also inhibited both NO production and lymphocytostatic activity of PAM, but in contrast to GM-CSF and TNF-alpha, TGF-beta was only active if present throughout the PAM:T-cell coculture period. Additionally, monocytes recruited into the lung by a sterile inflammatory stimulus are shown to be initially stimulatory towards T-cell activation, and to progressively develop both T-cell suppressive- and NO synthetic-capacity as they mature into mature PAM in vivo. Thus, during acute lung inflammation, a series of overlapping mechanisms are potentially available to bypass local immunosuppression: secretion of cytokines which are capable of temporarily abrogating the immunosuppressive activity of resident PAM, and the recruitment of permissive monocytes which exhibit potent accessory cell activity, the net result being the creation of a transient 'window' for induction of local T cell-mediated immunity.

Alveolar macrophages from humans and rodents selectively inhibit T-cell proliferation but permit T-cell activation and cytokine secretion.

Alveolar macrophages (AM) are thought to play a key role in the regulation of immune responses within the lung. While it is well established that AM inhibit T-cell proliferation in vitro, it is unclear whether other aspects of the T-cell activation process are also inhibited. The present study demonstrates that AM from rat, mouse and human differ markedly in the potency with which they inhibit mitogen-induced T-cell proliferation, although in humans the degree of inhibition approaches that observed in the animal systems, if antigen (as opposed to mitogen) is employed as the T-cell activating agent. Rodent and human AM also differ in the mechanisms employed to achieve this inhibition; rodent AM appear to utilize reactive nitrogen intermediates, while this does not appear to be the case for human AM. Despite these differences, T cells stimulated in the presence of AM display a similar phenotype in all species examined, i.e. CD3 down-modulation, up-regulation of interleukin-2 receptor (IL-2R) expression and IL-2 production, but inability to respond to IL-2. Thus, AM appear to allow T-cell activation and expression of T-cell effector function, while selectively inhibiting T-cell proliferation.

Inhibition of the immunosuppressive activity of resident pulmonary alveolar macrophages by granulocyte/macrophage colony-stimulating factor.

Resident pulmonary alveolar macrophages (PAM) play an important role in the maintenance of immunological homeostasis in the lung via downmodulation of local T cell responses in the steady state. The present study demonstrates that this pathway for T cell suppression is reversible via granulocyte/macrophage colony-stimulating factor (GM-CSF). Thus, freshly isolated PAM strongly inhibit mitogen-induced T cell proliferation, and pretreatment of the PAM with cytokine-rich lung-conditioned medium (LCM) generated by exposure of lung to bacterial lipopolysaccharide (LPS) abrogated this suppressive activity. LCM from lungs of normal and athymic nude mice exhibited identical activity. Moreover, the PAM-modulating activity of LCM was inhibited by blocking antibody specific for GM-CSF, and the activity of LCM could be reproduced by recombinant GM-CSF. This suggests that secretion of GM-CSF by mesenchymal cells and/or macrophages under stimulation from agents such as LPS provides a potential mechanism for upregulation of local T cell responsiveness during acute inflammation. In addition, experiments with a range of cytokines indicated that interleukin 4, transforming growth factor beta 1 and tumor necrosis factor alpha (TNF-alpha) exhibited weaker (but significant) modulatory effects on PAM, and (in the case of TNF-alpha) amplified the effects of GM-CSF.

Downregulation of the antigen presenting cell function(s) of pulmonary dendritic cells in vivo by resident alveolar macrophages.

Class II major histocompatibility complex (Ia)-bearing dendritic cells (DC) from airway epithelium and lung parenchyma express low-moderate antigen presenting cell (APC) activity when freshly isolated. However, this function is markedly upregulated during overnight culture in a manner analogous to epidermal Langerhans cells. The in vitro "maturation" process is inhibited by coculture with pulmonary alveolar macrophages (PAM) across a semipermeable membrane, and the degree of inhibition achieved can be markedly increased by the presence of tumor necrosis factor alpha. In addition, PAM-mediated suppression of DC function is abrogated via inhibition of the nitric oxide synthetase pathway. Functional maturation of the DC is accompanied by increased expression of surface Ia, which is also inhibited in the presence of PAM. Prior elimination of PAM from DC donors via intratracheal administration of the cytotoxic drug dichloromethylene diphosphonate in liposomes, 24-72 h before lung DC preparation, achieves a comparable upregulation of APC activity, suggesting that (consistent with the in vitro data) the resident PAM population actively suppresses the APC function of lung DC in situ. In support of the feasibility of such a regulatory mechanism, electron microscopic examination of normal lung fixed by intravascular perfusion in the inflated state (which optimally preserves PAM in situ), revealed that the majority are preferentially localized in recesses at the alveolar septal junctions. In this position, the PAM are in intimate association with the alveolar epithelial surface, and are effectively separated by as little as 0.2 microns from underlying interstitial spaces which contain the peripheral lung DC population. A similar juxtaposition of airway intraepithelial DC is demonstrated with underlying submucosal tissue macrophages, where the separation between the two cell populations is effectively the width of the basal lamina.

The surface phenotypic characterization of lung macrophages in C3H/HeJ mice.

We have investigated the surface phenotypic profile of murine lung macrophages in frozen tissue sections, in single-cell suspensions obtained by endobronchial lavage, and in collagenase digests of parenchymal lung tissue, using a panel of monoclonal antibodies directed against pan macrophage markers and antigens present on distinct lymphoid-associated macrophage subpopulations. Our results indicate that lung macrophages from specific pathogen-free (SPF), lipopolysaccharide (LPS) hyporesponsive C3H/HeJ mice are relatively homogeneous no matter what lung tissue compartment they are obtained from. Their predominant surface phenotype was F4/80weak, M1/70-, MOMA-2+, NLDC-145+, MOMA-1+, SER-4+, which resembles the pattern of expression by lymphoid macrophages rather than representative tissue macrophages such as those found in the peritoneal cavity. These results are consistent with the current paradigm that lung macrophages, like lymphoid macrophages, play an important immunoregulatory role within their microenvironment.

Immunoregulation of asthma: control of T-lymphocyte activation in the respiratory tract.

Allergic asthma results ultimately from inappropriate responses to non-pathogenic airborn antigens by the respiratory tract T-cell system. In order to understand how sensitization to inhaled antigens develops, it is necessary to precisely define the tissue microenvironments within which T-cells occur in the respiratory tract, and to analyse the factor(s) which regulate their local activation. This review focuses upon recent data on the distribution of T-cells and antigen presenting cells within the lung and airway tissues of man and experimental animals, and examines the available information on their responses to antigenic stimulation. We argue that in the steady state, respiratory tract T-cells are tightly regulated by a series of inherent and acquired immunosuppressive control mechanisms, which normally limit local T-cell activation to situations where antigenic exposure is accompanied by an inflammatory stimulus, such as the case with incoming pathogenic microorganisms.

In vivo arming of cutaneous mast cell receptors by IgE released from macrophages.

Intracutaneous injection of purified peritoneal macrophages harvested from ovalbumin (OVA)-hypersensitive high-IgE-responder BN rats into naive animals sensitised the injection sites for subsequent OVA-specific passive cutaneous anaphylaxis (PCA) reactions. The underlying mechanism(s) were investigated using a macrophage cell line (WEHI 265.1), which exhibited comparable sensitising activity in rat or mouse skin, after initial pulsing in vitro with antiserum rich in OVA-specific IgE. Transfer of OVA-hypersensitivity by the cell line (1) was IgE-dependent and did not occur when the cells were pre-exposed to antiserum containing OVA-specific IgG alone, (2) was blockable by saturation of cell surface receptors in the recipient with myeloma IgE (but not myeloma IgG), and (3) did not occur in mast cell-deficient mice carrying the W/Wv mutation, in contrast to their normal heterozygous littermates which developed marked OVA-hypersensitivity at the injection site. These results are consistent with arming of IgE-receptors on cutaneous mast cells by IgE antibody released from macrophages, and hint at a possible role for phagocytes in amplifying IgE-mediated reactions in tissues.

Functional studies on macrophage populations in the airways and the lung wall of SPF mice in the steady-state and during respiratory virus infection.

Collagenase digestion of slices of lavaged and perfused murine lung from SPF animals yielded, on average, 104 x 10(6) mononuclear cells per gram tissue, including approximately 14% F4/80+ macrophages and 35% lymphocytes. The lung tissue-associated (digest) macrophage (LDM) population was 10-fold higher in number than the alveolar macrophage (AM) population recoverable by lavage. Comparative functional analysis of these populations was performed, employing assays for immune receptors (Fc and C3), complement-induced spreading, endogenous peroxidase, IL-1 secretion and tumour cytolysis; resident and activated peritoneal macrophages and blood monocytes were examined in parallel. The resident LDM population exhibited an activation status intermediate between blood monocytes and the relatively more activated AM from the airways. Murine lung macrophages were also examined during an acute influenza infection and LDM and AM recoveries increased significantly. The AM population exhibited activation during an acute infection. In contrast, LDM remained quiescent, despite the influx of a large number of T lymphocytes into the lung wall. These results suggest that LDM may be intrinsically resistant to the signals generated during T-cell-mediated eradication of influenza, or else local tissue factors modulate T-cell-derived activation signals.

Limiting-dilution analysis of T cells extracted from solid human lung tissue: comparison of precursor frequencies for proliferative responses and lymphokine production between lung and blood T cells from individual donors.

This study evaluates the frequency and functions of immunocompetent T cells at the clonal level in solid human lung tissue versus peripheral blood. Enzymatic digestion of slices of histologically normal human lung yielded 18-42 x 10(6) viable mononuclear cells per gram wet weight tissue, of which 60-72% were lymphocytes; based upon these recoveries and the known weight of adult lung, the (median) lung parenchymal lymphocyte population can be estimated as 6 x 10(9), being of the same order as the blood pool and 15-30-fold that recoverable by broncho-alveolar lavage. Flow cytometric analysis indicated that the bulk of these lymphocytes was OKT3+/T11+ (CD3/CD2) T cells. Purified blood and lung T cells from each subject were cultured at limiting dilution in the presence of PHA, irradiated feeder cells and recombinant human IL-2. The mean frequency estimates for PHA-responsive T cells in these populations were 1 in 1.23 (81%) and 1 in 3.22 (31%) for blood and lung, respectively. This difference was seen for T cells from each donor and was highly significant by paired t-test (P less than 0.002). Analysis of surface phenotypes and functions of individual blood and T-cell clones indicated comparable frequencies for OKT4 (CD4) and OKT8 (CD8) expression, TNF production and mitogen-induced cytotoxicity. However, a striking inverse relationship was observed between the overall frequency of IL-2-producing clones (79% for blood versus 47% for lung) and interferon-gamma (IFN-gamma)-producing clones (46% versus 87%). These differences were found for each subject, and both were highly significant (P less than 0.001) by paired t-test. The available literature suggests that the majority of these lung T cells represent transient immigrants derived from the blood. Accordingly, the functional differences we have observed suggest either selective trapping within the lung vascular bed of peripheral blood T cells of certain functional phenotypes or alternatively selection/modulation of T cells by lung-derived factors during their transit through the tissue.

Effect of influenza virus infection on allergic sensitization to inhaled antigen in mice.

Repeated exposure of healthy mice to an aerosol of ovalbumin (OA) leads to the development of IgE-isotype-specific immunological tolerance. However, when initial OA exposure occurs during the acute phase of influenza infection, tolerance does not occur, and the mice instead develop high titres of OA-specific IgE in response to subsequent challenge with the allergen.