Age dependence of spontaneous plaque forming cells in human peripheral blood in Graves disease, rheumatoid arthritis and normal subjects.

A protein A plaque forming cell (PFC) assay has been used to assess immunoglobulin synthesis by peripheral blood lymphocytes (PBL) from normal subjects and patients with Graves' disease and rheumatoid arthritis. In normal subjects the number of PFC detected immediately after lymphocyte isolation showed a marked decrease with increasing age. In addition, PBL from patients with Graves' disease or rheumatoid arthritis contained similar numbers of PFC to age-matched control subjects. These findings suggest that patients with these immunological disorders do not show polyclonal B cell activation.