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Co‐mitogenic assay for assessing the effects of aflatoxin B 1 on interleukin‐1 production in bovine macrophages
Author(s) -
Walsh Catherine J.,
Bodine Ashby B.,
Scott Thomas R.
Publication year - 1991
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.430240203
Subject(s) - aflatoxin , concanavalin a , thymocyte , thymidine , microbiology and biotechnology , lipopolysaccharide , phorbol , dna synthesis , chemistry , biochemistry , biology , dna , endocrinology , immunology , in vitro , t cell , immune system , food science , phosphorylation , protein kinase c
Previous research has shown that aflatoxin B 1 (AFB 1 ) markedly decreases the uptake of tritiated thymidine in bovine peripheral lymphocytes. Currently, the immunosuppressive activities of aflatoxin B 1 are being investigated further using bovine macrophages as a model cell type. Polystyrene‐adhered macrophages demonstrated a 50% reduction in up‐take of tritiated thymidine at 10 μg/mL aflatoxin B 1 . The distribution of 3 H‐AFB 1 in bovine macrophages was investigated to study mechanisms by which AFB 1 may be exerting immunosuppressive effects. Only 12.96% of the incorporated 3 H‐AFB 1 was taken into nuclear DNA, whereas 80.13% remained in the cytosolic fraction. A co‐mitogenic assay was developed to ascertain the correlation between reduced tritiated thymidine uptake, binding of 3 H‐AFB 1 to nuclear DNA, and interleukin‐1 (IL‐1) production and/or activity. Conditioned media containing interleukin‐1 activity was prepared by culturing macrophages for 24 hr with 2.5 μg/mL lipopolysaccharide, 45 ng/mL phorbol myristate acetate, with or without 10 μg/mL aflatoxin B 1 . The conditioned media was used in a co‐mitogenic assay with calf thymocytes as target cells. In this assay, the response of calf thymocytes to conditioned media from AFB 1 ‐treated cells did not differ from the response to control conditioned media. In addition, AFB 1 added to thymocyte cultures co‐stimulated with conditioned media and concanavalin A (ConA) greatly diminished the thymocyte response to co‐stimulation. The data support the conclusions that the immunosuppressive effects of AFB 1 on the bovine macrophage and T lymphocyte may not be directly related via impaired IL‐1 production. The blinding of AFB 1 to macrophage DNA was not sufficient to produce any detectable effect on interleukin‐1 production by bovine macrophages.