Serum antibodies to cytoskeletal systems were measured by indirect immunofluorescence using human skin fibroblasts and HEp2 cells as substrate. Healthy adults had IgM antibodies to vimentin and cytokeratin at 60 times serum dilution. IgG concentration did not have a correlation with IgG anti-cytoskeletal system antibodies and IgM concentration correlated with anti-vimentin and anti-cytokeratin antibodies.
In patients with adult T-cell leukemia (ATL), IgG antibody titer against actin and vimentin was increased in spite of a decreased IgG concentration. IgM antibodies to vimentin was decreased in its titer together with a decreased IgM concentration. Antibody titer to HTLV-1, leukemic cell counts in peripheral blood and disease type, acute or chronic, did not have correlations with anti-cytoskeletal system antibodies. A third of the patients with ATL showed negative anti-EBNA antibody, suggesting that the functional impairment in EBV-specific killer cells was present.
In contrast, the patients with infectious mononucleosis showed increased serum IgM concentration and IgM anti-vimentin antibody titer. It was suggested that the autoantibodies to cytoskeletal systems associated with viral infection were mainly composed of IgG in ATL and of IgM in infectious mononucleosis.