<prompt> Which of the following is a major cell infiltrate in rheumatoid arthritis?CD4helper cellMacrophageLymphocyteDendritics cells  <response>: Ref. Robbins Pathology. 9th edition. Page. 1209Rheumatoid ArthritisCD4 T helper TH cells may initiate the autoimmune response in RA by reacting with an arthritogenic agent, perhaps microbial or a self-antigen IFN-γ from TH1 cells activates macrophages and resident synovial cells.IL-17 from TH17 cells recruits neutrophils and monocytes.TNF and IL-1 from macrophages stimulates resident synovial cells to secrete proteases that destroy hyaline cartilage.RANKL expressed on activated T cells stimulates bone resorption.Microscopy:The characteristic histologic features includeSynovial cell hyperplasia and proliferationDense inflammatory infiltrates frequently forming lymphoid follicles of cd4 helper t cells, b cells, plasma cells, dendritic cells, and macrophagesIncreased vascularity due to angiogenesisFibrinopurulent exudate on the synovial and joint surfaces;Osteoclastic activity in under- lying bone 