Down-regulation or blocking cell surface tTG decreases adhesion of THP-1 cells and human peripheral blood monocytes on Fn and the 42-kd Fn fragment.

(A-C) Cells (2 × 10⁴) were plated for 1 hour at 37°C in serum-free AIM-V medium containing 0.5% BSA on protein-coated wells. (A) THP-vector (░) and THP-antisense (▨) cells were stimulated for 1 hour with 150 ng/mL TPA and then allowed to adhere to wells coated with collagen type I (Col I), laminin (Ln), Fn, 110-kd or 42-kd Fn fragments, or BSA. Some samples of THP-vector cells were pretreated for 1 hour with function-blocking polyclonal anti-tTG antibody (■). (B) THP-vector (■) and THP-antisense cells (▧), either untreated or pretreated for 1 hour with 150 ng/mL TPA (░, vector; ▨, antisense), were allowed to adhere on Fn-coated wells. Some samples of TPA-stimulated THP-vector cells were preincubated for 1 hour with function-blocking polyclonal anti-tTG antibody, blocking mAbs against β₁-, β₂-, or β₃-integrins, antibody against FXIIIA, or control nonimmune IgG. (C) Human peripheral blood monocytes were treated for 4 hours with 5 ng/mL M-CSF and then plated on wells coated with Fn (■) or the 42-kd fragment of Fn (▪). Monocyte samples were preincubated for 1 hour with control nonimmune IgG, function-blocking polyclonal anti-tTG antibody, mAb 4G3 against tTG, or blocking mAbs against β₁-, β₂-, or β₃-integrins. (A-C) The antibodies were kept in the medium during the assay. Shown are the means of 3 separate experiments performed in duplicate.