Susan L. Foster

Human rheumatoid factor producing cell induction by 2-mercaptoethanol: Immunomodulation by a simple thiol compound

Two-mercaptoethanol (2-ME), a simple 2 carbon thiol compound with a wide variety of in vitro and in vivo immunomodulating effects, was evaluated for its usefulness as a molecular probe of human antibody producing cell activation by adding 2-ME to cultures of peripheral blood mononuclear leukocytes from normal human volunteers. Culturing normal human leukocytes with 2-ME induced a significant number of cells producing rheumatoid factor as measured by a hemolytic plaque forming cell (PFC) assay. Dose response studies revealed 5 X 10(-5)M to be the optimum concentration of 2-ME for the induction of rheumatoid factor plaque forming cells (RF-PFC). This concentration of 2-ME also maximally induced PFC making antibodies to sheep red cells coupled to the trinitrophenyl (TNP) hapten demonstrating that 2-ME is a polyclonal inducer of human PFC. The addition of 5 X 10(-5) M 2-ME to cultures containing maximal concentrations of the polyclonal stimulators, pokeweed mitogen and human heat-aggregrated IgG, increased the number of RF-PFC detected in these cultures by approximately 50%, although both lower and higher concentrations of 2-ME suppressed the RF-PFC response. We conclude that 2-ME induces normal human leukocytes to produce rheumatoid factor as part of a polyclonal activation of antibody producing cells. 2-ME also has immunomodulating effects when added to other polyclonal stimulators of antibody producing cells.

Induction of Autoantibody-Producing Cells after the Coculture of Haptenated and Normal Human Mononuclear Leukocytes

Abstract The coculture of normal human peripheral blood mononuclear leukocytes (PBL) and autologous mononuclear leukocytes coupled to the trinitrophenyl (TNP) hapten (TNP-PBL) was found to induce a polyclonal activation of antibody-producing cells. The polyclonal activation of antibody-producing cells was demonstrated by detecting the induction of cells producing antibody to sheep red blood cells using a complement-dependent, direct, hemolytic plaque-forming cell (PFC) assay. A ratio of four normal to one haptenated mononuclear leukocyte was found to be optimal for inducing the polyclonal activation of antibody-producing cells in these cultures. The plaque-forming cell assay in these experiments utilized monolayers of indicator red cells. Further evidence for the polyclonal induction of antibody-producing cells by TNP-PBL was provided by demonstrating PFC on monolayers of not only sheep red blood cells, but also autologous human red cells, bromelain-treated autologous red cells, TNP-coupled human and sheep red cells, and human autologous red cells coupled to human heat-aggregated IgG with chromic chloride. Thus cells secreting antibody to TNP, human red cells, and human IgG were induced. Anti-IgG and anti-human red cell-producing cells were first detected on Day 2 of culture and were still present on Day 9. Mononuclear leukocytes altered by chemical haptenation polyclonally stimulate normal mononuclear leukocytes to become antibody-producing cells. This polyclonal stimulation of antibody-producing cells includes cells producing antibodies to human IgG and human autologous red blood cells suggesting that autoantibody-producing cells are induced.

Spontaneous and aggregated IgG induced rheumatoid factor producing cells in rheumatoid arthritis.

SummarySeropositive rheumatoid arthritis (RA) patients were found to have high numbers of spontaneously occurring cells making rheumatoid factor (RF) reactive with human IgG as measured by a RF plaque forming cell (RF-PFC) assay. There was a significant positive correlation between the number of RF-PFC and both disease activity measured by the sedimentation rate and RF titer measured by the RA latex test. Aggregated IgG and pokeweed mitogen were equally effective stimulators of RF-PFC in cultures of RA peripheral blood mononuclear leukocytes. The rheumatoid ratio of helper (T4): suppressor (T8) T lymphocytes was also significantly increased over the ratio of normal controls, but this ratio did not correlate with the number of RF-PFC. Aggregated IgG or immune complexes may be responsible for stimulating RA RF-PFC in vivo.