Inflammatory cell and cytokine patterns in patients with painful clicking and osteoarthritis in the temporomandibular joint

The occurrence of a subset of cytokines and leukocytes in the posterior disc attachment area of the temporomandibular joint (TMJ) was investigated in two patient groups, i.e, one group with painful clicking and one with osteoarthritis. Synovial biopsies were taken during discectomy in 19 patients with painful clicking and 20 with osteoarthritis. One set of specimens was examined with immunohistochemistry, using frozen sections postfixed by para-formaldehyde and with the cell membranes permeablized in saponin. These sections were incubated with antibodies against cytokines IL-1alpha, IL-1beta, IL-1ra, TNFalpha, IFNgamma, IL2 in all patients and TGFbeta1,2,3 in 16. The other set of specimens was used to characterize cell infiltrates using immunohistochemistry with monoclonal antibodies against antigens CD68 and CD45RO, respectively. Moreover, PCNA was included as a marker for cell proliferation. The cytokine staining was most frequently positive for IL-1alpha and IL-1beta in both patient groups. However, joints with OA showed a more complex cytokine pattern, also involving IFN-gamma (P=0.019), IL-ra (P=0.047), and apparently but without reaching the chosen level of significance, IL-2, TNF-alpha and TGF-beta1,2,3. Positive staining for CD45RO was frequent in both groups. OA patients showed more frequently positive staining for CD68 (P=0.025) and apparently for PCNA.