Functional heterogeneity of culture-grown bone marrow-derived macrophages. II. Lymphokine stimulation of antigen-presenting function
Lee, K.C.; Wong, M.
Journal of Immunology 128(6): 2487-2492
1982
ISSN/ISBN: 0022-1767 PMID: 6978905 Document Number: 185295
The activation of immunostimulatory activity and Ia expression was studied in pure populations of murine macrophages (M.vphi.) grown in vitro from bone marrow precursor cells in the presence of L cell-conditioned medium as the source of colony-stimulating factor. During exponential growth, the M.vphi. developed maximal Ia-dependent antigen-presenting activity as detected by the induction of antigen-specific T cell proliferation, but the proportion of Ia+ M.vphi. was low (< 10%). Fractionation of the M.vphi. according to size by velocity sedimentation resulted in concentration of the antigen-presenting cells in the smallest fraction, but the enrichment of Ia+ M.vphi. in this fraction was < 2-fold. All fractions also showed comparable degrees of antigen uptake regardless of their T cell-stimulating activity. Thus Ia and antigen, although obviously essential, are insufficient for full manifestation of antigen-presenting function. Activation of M.vphi. with lymphokines from Mycobacterium-activated lymph node cells resulted in enhanced Ia expression in all fractions, but only small M.vphi. showed an enhancement in antigen presentation. Large activated M.vphi. were found to exert an immunosuppressive effect that probably neutralized any augmentation in stimulatory activity. Thus, heterogeneity can be demonstrated in the function of unstimulated M.vphi., the responsiveness of subsets to stimulation and the manifestation of activated functions.