Heterogeneity in immunologic functions of rat alveolar macrophages--their accessory cell function and IL-1 production

Our plain-English summary of Heterogeneity in immunologic functions of rat alveolar macrophages--their accessory cell function and IL-1 production, by Y. Oghiso (Microbiology and Immunology, 1987).

The study

• Author: Y. Oghiso
• Journal: Microbiology and Immunology
• Published: 1987;31(3):247-60
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Alveolar macrophages (AM) from normal rats were separated into 4 different density fractions by centrifugation on a discontinuous Percoll gradient. These fractionated (I-IV) AM, as well as unfractionated (UF) AM, were then tested for their capacities to regulate mitogen-induced T cell proliferation. Concanavalin A (Con A)-induced response of nylon wool-passed non-adherent splenic T lymphocytes was suppressed by addition of UF or higher density (III and IV) AM, while an intermediate density (II) AM fraction could enhance T cell response in a dose-dependent manner. Similar effects of UF or fractionated (I-IV) AM on T cell responses were noted when the cultures were exposed in vitro to inert, non-fibrogenic titanium dioxide (TiO2) particles. On the contrary, T cell response was sustained by addition of UF or higher density (III and IV) AM, and was also more prominently enhanced by an intermediate density (II) AM after the in vitro exposures to fibrogenic dust particles, like silica and asbestos. Higher interleukin 1 (IL-1) activity was detected from these silica- or asbestos-exposed cultures of UF and fractionated (II, III, and IV) AM. The IL-1 activity was also highly detectable from the cultures of an intermediate density (II) AM fraction when cultures were unexposed or exposed in vitro to TiO2 particles. The Ia antigen expression on the surface of UF or fractionated (II, III, and IV) AM was elevated in the Con A-pulsed co-cultures, but not significantly different whether or not they were exposed in vitro to dust particles. These results may indicate the presence of heterogeneity in accessory cell functions and IL-1 production among rat AM.

In plain English

This laboratory study examined whether lung immune cells called alveolar macrophages, taken from healthy rats, differ in how they influence T cells. The macrophages were separated by density into four fractions (I to IV) and cultured with stimulated T cells from the same rats' spleens. Some cultures were exposed to silica, crocidolite asbestos or titanium dioxide particles. Unfractionated macrophages suppressed T cell growth but supported it after exposure to silica or asbestos. Titanium dioxide-exposed macrophages suppressed it like unexposed ones. The intermediate-density fraction (II) enhanced T cell growth, more prominently with silica or asbestos. The denser fractions (III and IV) suppressed it in unexposed and titanium dioxide-exposed cultures. In silica- or asbestos-exposed cultures, they sustained it when fewer cells were added. Interleukin 1 activity (an immune signal) was higher in silica- or asbestos-exposed cultures of unfractionated macrophages and fractions II to IV. Fraction II was also high without these particles, and fraction I stayed much lower. Interleukin 2 levels and the Ia surface marker did not clearly differ with particle exposure. The author concluded the results may suggest heterogeneity among rat alveolar macrophages, with its origin unclear.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) experiment on cells from rats
• Who was studied: Alveolar macrophages from normal three-month-old male inbred Wistar rats, separated into 4 density fractions and co-cultured with T cells from the same rats' spleens. The number of rats is not stated.
• Exposure: In vitro exposure of cultures to crocidolite asbestos (UICC Standard Reference Preparation), microcrystalline silica, or titanium dioxide particles, each at 100 micrograms per milliliter
• Main results:
  • Unexposed unfractionated macrophages suppressed concanavalin A-induced T cell responses. After in vitro exposure to silica or asbestos, macrophages sustained these responses more efficiently.
  • Unfractionated macrophages and fractions III and IV exposed to titanium dioxide had suppressive effects similar to unexposed macrophages.
  • After fractionation, only the intermediate-density fraction (II) enhanced T cell proliferation in unexposed cultures.
  • In silica- and crocidolite-exposed cultures, the higher-density fractions (III and IV) sustained lymphocyte responses when a smaller number of cells was added.
  • The lowest-density fraction (I) had little effect on T cell responses, with or without particles.
  • In silica- or asbestos-exposed cultures, the intermediate-density fraction (II) and the higher-density fractions (III and IV) produced interleukin 1 at a higher level.
  • Interleukin 1 production was higher in cultures of unfractionated macrophages exposed to silica or asbestos. It was not detected from unexposed or titanium dioxide-exposed cultures of unfractionated macrophages.
  • In unexposed or titanium dioxide-exposed cultures, only the intermediate-density fraction (II) showed higher interleukin 1 activity.
  • Cultures of the lowest-density fraction (I) had much lower interleukin 1 activity, whether unexposed or exposed to any of the particles.
  • Interleukin 2 levels were almost similar among co-cultures, whether or not they were exposed to particles.
  • Expression of the Ia surface antigen on macrophages rose during culture, but there were no significant differences between unexposed and particle-exposed cultures.
• The authors' conclusion: The author suggested that rat alveolar macrophages can be activated by fibrogenic mineral particles, but not by non-fibrogenic particles, to act as accessory cells for T cell responses. The author also concluded that the different responses of the fractions may suggest immunologic heterogeneity among these cells.
• Limitations the authors state:
  • The author stated that it remains unclear whether this heterogeneity reflects distinct subpopulations of macrophages or changes associated with cell maturation in the lung.

Topics

Medical terms in this study, explained in our Lexicon: Alveolar Macrophage, Fibrogenic.

Related studies

• Interleukin 1 production and accessory cell function of rat alveolar macrophages exposed to mineral dust particles — Y. Oghiso, Y. Kubota (1987)
• Selective differences in macrophage populations and monokine production in resolving pulmonary granuloma and fibrosis — I. Lemaire (1991)
• Enhanced interleukin activity following asbestos inhalation — D.P. Hartmann, M.M. Georgian, et al. (1984)
• Pulmonary reaction to long and short asbestos fibers is independent of fibroblast growth factor production by alveolar macrophages — I.Y. Adamson, D.H. Bowden (1990)
• Stimulation of oxidant production in alveolar macrophages by pollutant and latex particles — G.E. Hatch, D.E. Gardner, et al. (1980)
• Differences between particulate and peptide stimuli on activation of oxidant production in alveolar macrophages — G.E. Hatch, A. Spock, et al. (1980)

Browse return to medical research.