TLR4 and Arthritis: However, adoptive transfer of Gr-1+ cell-depleted spleen cells only partially restored joint inflammation in TLR4-/- mice, indicating that Gr-1+ cells contribute less significantly to the promotion of antibody-induced arthritis via TLR4-mediated signals than macrophages and mast cells, although Gr-1+ cells play a crucial role in the development of joint inflammation.