Dectin-1 functions to promote TNF-α production in M smegmatis– and M avium 2151–infected macrophages. BMMϕs were infected with (A) M smegmatis or M avium 724 or M avium 2151 in the presence of PBS or anti–dectin-1 mAb 2A11 or isotype control Ab, (B) M smegmatis in the presence of laminarin or galactan, and (C) complement opsonized or nonopsonized M smegmatis in the presence of PBS, 2A11, or isotype control Ab. Also shown are LPS-treated BMMϕs with or without antibodies. Culture supernates after 24 hours of infection were analyzed for TNF-α by ELISA. *Significant to M smegmatis plus PBS (P < .01). **Significant to M smegmatis alone and M smegmatis plus galactan (P < .01). Values are expressed as means + SD. Data are representative of 3 separate experiments. Iso-Con indicates isotype control Ab; Smeg, M smegmatis; and RC, noninfected BMMϕs.