These constructs antagonize the cognate TCR and bind with high affinity to their cell-bound CD74 receptor on macrophages and dendritic cells, thereby competitively inhibiting downstream signaling and pro-inflammatory effects of macrophage migration inhibitory factor (MIF) and its homolog, D-dopachrome tautomerase (D-DT=MIF-2) that bind to identical residues of CD74 leading to progressive disease.