Human T lymphocyte receptors for IgM: control by IgG-binding lymphocytes.

The capacity of human peripheral blood lymphocytes to bind antigen-IgG or antigen-IgM-antibody complexes was investigated using a rosette technique with ox erythrocytes (E) coated with rabbit IgG (AG) or IgM (AM) antibodies. EAM rosette formation was achieved only in suspensions pre-incubated for 24 h at 37 degrees C. Addition of either EAM or EAG complexes to the culture medium was shown to prevent the formation of EAM rosettes. The inhibition was reversible, it was not due to trace IgM contaminants in the IgG antibody fraction. It was not observed when lymphocytes depleted of EAG-rosetting cells were incubated with EAG complexes. Inhibition of the expression of lymphocyte receptors for IgM can be regarded as a consequence of the modulation of surface receptors for IgG and involves an interaction between the two lymphocyte subsets bearing surface receptors for IgG and IgM, respectively. However, these experiments do not exclude the possibility that a few cells which bind EAG may lose their receptors by modulation and then express a receptor for IgM.