Tumor necrosis factor (TNF)-alpha is a key proinflammatory cytokine that is thought to be important in the development of pulmonary fibrosis, whereas its role in pulmonary emphysema has not been as thoroughly documented. In the present study, TNF-alpha was overexpressed in alveolar type II cells under the control of the human surfactant protein C promoter. In this report, we further characterized the pulmonary abnormalities and provided a physiological assessment of these mice. Histopathology of the lungs revealed chronic inflammation, severe alveolar air space enlargement and septal destruction, and bronchiolitis. However, pulmonary fibrosis was very limited and only seen in the subpleural, peribronchiolar, and perivascular regions. Physiological assessment showed an increase in lung volumes and a decrease in elastic recoil characteristic of emphysema; there was no evidence of restrictive lung disease characteristic of pulmonary fibrosis. In addition, the mice raised in ambient conditions in Denver developed pulmonary hypertension. Gelatinase activity was increased in the lavage fluid from these lungs. These results suggest that in these mice TNF-alpha contributed to the development of pulmonary emphysema through chronic lung inflammation and activation of the elastolytic enzymes but by itself was unable to produce significant pulmonary fibrosis.

The biological role of cells bearing the gamma delta T-cell antigen receptor (TCR) is as yet unclear. Although there are indications that some gamma delta+ cells can mediate cytotoxicity, their antigen-related functions have not yet been defined. In the mouse, gamma delta+ cells constitute 1-3% of T cells in lymphoid organs. Intestinal intraepithelial lymphocytes (IELs) and dendritic epidermal cells (DECs) also appear to carry the gamma delta TCR. The strategic locations of DECs and IELs have led to the suggestion that gamma delta+ cells could constitute a first line of defence in the vicinity of large surfaces of contact with the environment. We report here that an estimated 8-20% of resident pulmonary lymphocytes (RPLs) are CD3+ alpha beta TCR-, and presumably gamma delta TCR+. Furthermore, mice exposed to aerosols containing a Mycobacterium tuberculosis extract have an increased number of activated CD3+ alpha beta-TCR- pulmonary T cells which can be propagated in vitro.

The analysis of B-cell triggering mechanisms and clonal regulation has been successfully approached with ligands that are competent to activate a large fraction of all cells (1-3). Polyclonal activation of B cells has also proved to be a useful tool in studying Ig synthesis and secretion (4), in the analysis of functional B-cell subpopulations (5) and their development (6), and in the description of the antibody repertoire (7,8) by allowing the determination of relative frequencies of clonotypes in the absence of antigen selection.Each B-cell mitogen known to date activates only a fraction of all bone marrowderived lymphocytes (9, 10). Although some discrepancies in quantitative aspects of the problem still exist, it is now clear that partially distinct subsets of B cells respond to the various mitogens (5,11,12). In particular, much attention has been focused on the existence of B-cell subpopulations responding to either thymus-independent or thymus-dependent forms of the same antigenic determinants (13-16). As was pointed out before (10), this cell population that secretes antibodies subsequently to T cellmacrophage help has thus far escaped all analyses using direct B-cell mitogens. The study of this cell subset would provide new information on both its antibody repertoire and the mechanism of cooperative B-cell triggering which, to date, remains controversial (17).We attempted to develop a system for polyclonal B-cell induction mediated by T cells, in the absence of extraneously added ligands, such as antigen or mitogen. Previous experiments by Cammisuli et al. (18) had already indicated that cooperative B-cell induction could take place in the absence of specific interactions involving Ig receptors on the responding B cell, by using helper cell recognition of determinants artificially attached to B-cell surfaces. We have now improved that approach with three major modifications. To ensure that the antigens would remain on the B-cell surface throughout the cooperative culture, we activated T cells directly against minor antigens expressed on B-cell surfaces. Furthermore, we used an in vitro system by which a manifold enrichment of specific helper cells can be achieved. Finally, we measured the responses of all B cells, regardless of their antibody specificity. In this way, a very high frequency of specific T-B cell interactions was obtained in the helper assay, and this might make the system an optimal tool for the study of T-B cell collaboration.

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The anti-PC antibodies of BALB/c origin bear predominantly the idiotype characteristic of the phosphorylcholine (PC)-binding T15 idiotype than sera from adult mice, and, unlike the latter, they also contain detectable amounts of anti-T15 antibodies. By 2 weeks of age the anti-T15 antibodies are no longer detectable while the T15 idiotype has reached adult levels. Injection of neonatal mice with anti-idiotypic antibodies renders them unresponsive to PC until the 15th week of life. Furthermore, this treatment induces a chronic suppression of the T15 idiotype, since on recovery from unresponsiveness, the neonatally suppressed mice produce anti-PC antibodies which are predominantly T15-negative. In contrast, treatment of adult mice with anti-idiotypic antibodies induces only a transient state of unresponsiveness to PC, and the antibodies produced upon recovery bear the T15 idiotype. These findings are discussed in the context of idiotype anti-idiotype interactions and their possible role in immuno-regulation.

At birth, T lymphocytes which colonize the lung are mainly of the y6 subset, while a/3 T cells predominate in the spleen. Thus, the lung is a preferred site for the homing of yS T cells in the perinatal period. However, after birth, the pattern of V T gene usage among resident pulmonary lymphocytes (RPL) changes with age, from a predominance of V T 6 at birth to a predominance of V T 4 in older mice. The generation of the V 7 6 fraction appears to be thymus dependent, since In athymic nude mice, the V T 6 population present at birth Is replaced by V T 4 T cells. In the postnatal period, both RAG-1 and RAG-2 genes are expressed at high levels In the RPL population. TCR bearing cells are among those that express RAG genes, Indicating that maturation of T cells takes place In this organ. In addition, transfer experiments reveal that lymphoid precursors are present In the lung. The stage of differentiation of these precursors will be characterized in future studies. The data presented here Indicate that pulmonary T lymphocytes are derived from both migrants of thymlc origin and from precursors which have undergone differentiation and selection in the lung. The population that Is generated In situ and that has not been selected In the thymus may Include cells that are typical for the pulmonary environment.

We have investigated the effects of heat shock on T-cell induction and selection in vitro. We find that when cell preparations containing T lymphocytes are incubated for 30 min at 42TC, a selective proliferation of y68 T cells bearing the y8 T-cell antigen receptor follows. A greater enrichment of Y6+ T cells is observed, upon preexposure to mycobacterial antigens in vivo. By comparing the effects of heat shock with that of mitogen or specific T-cell triggering by conventional antigens and by analyzing the v6 T-cell receptor genes expressed in cells that proliferate as a result of heat shock induction, we conclude that a subset of murine y8 T cells react to antigens on self cells in which a heat shock response was induced. GBq) was added to the medium and the cells were cultured in a 5% C02/95% air incubator for a further 6 hr.Cell Cultures. Lymphocyte suspensions from lymph nodes were prepared by standard procedures, and RPL populations were prepared as described (10). Cells were cultured in Iscove's modified Dulbecco's medium supplemented with 10% fetal calf serum essentially as described (10, 11). Where applicable, lymphokines added after 3 days in culture were recombinant interleukin 1 and recombinant interleukin 2 (10 units/ml and 40 units/ml, respectively; gifts of P. Lomedico, Roche, Nutley, NJ). In general, 5 days after the addition of lymphokines, viable cells were analyzed. Where indicated,

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