A 150-kDa molecule of macrophage membrane stimulates interleukin-2 and interferon-γ production and proliferation of ovalbumin-specific CD4<SUP>+</SUP> T cells

In the present study, we describe the potential co-stimulatory role of a macrophage membrane-associated protein of 150 kDa (M150). The protein was isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was found to be a single molecule on two-dimensional gel electrophoresis. The molecule was re-constituted in phosphatidyl choline vesicles and tested for its ability to promote the proliferation and the secretion of lymphokines from T helper (Th) cells. The reconstituted M150 induced a significant proliferation of anti-CD3 monoclonal antibody (mAb)-stimulated ovalbumin-specific CD4<SUP>+</SUP> T cells. Further, Th cells activated with this molecule in the presence of anti-CD3 mAb mainly secreted interleukin (IL)-2 and interferon- but not IL-4. M150 could not promote the proliferation of Th cells, or lymphokine secretion in the absence of anti-CD3 mAb. These observations suggest that M150 acts by selectively activating a Th1-like immune response