CD40LG and arthritic joint disease: We have previously shown that a recombinant human IgG1 Fc with a point mutation at position 309, replacing a leucine with a cysteine, fused to the human IgM tailpiece to form a human IgG1 Fc hexamer, rFc-μTP-L309C, effectively prevents neutrophil infiltration into the joints and ameliorates arthritis in the K/BxN serum transfer model and in the endogenous chronic arthritis K/BxN model.