Detailed immunohistologic evaluation of a methotrexate-induced nodule.
Accelerated nodulosis in patients with rheumatoid arthritis who are receiving methotrexate has become a well-recognized phenomenon, and it appears to occur in both individuals with seropositive and seronegative findings. No histologic differences permit a distinction between seronegative and seropositive nodulosis--either occurring during the natural history of rheumatoid arthritis or when "induced" by methotrexate. We examined such a nodule in a man with seronegative rheumatoid arthritis. Results of immunofluorescence examination were not contributory, but studies of the inflammatory cell populations within the nodule showed 5% of the cells to be lymphocytes with a CD4/CD8 ratio of 25:1. Of the total mononuclear cells, 85% were reactive for Leu-10 (HLA-DQ) and 95% were reactive for HLA-DR, and about 75% of the macrophages were reactive for CD4+. The strong expression of CD4, in conjunction with macrophage markers, and the high T-helper/suppression ratio are of note. We discuss the implications of these findings and the role that they play in the pathogenesis of methotrexate-induced nodules.
DiFrancesco
L
L
Department of Pathology, State University of New York, Stony Brook 11794-8691.
Miller
F
F
Greenwald
R A
RA
D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D016516:CD4-CD8 Ratio; D006681:HLA-D Antigens / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008727:Methotrexate / Q000009:adverse effects*; D008875:Middle Aged; D009336:Necrosis
D006681:HLA-D Antigens; D008727:Methotrexate