The dynamic state of the lymphocyte membrane. Factors affecting the distribution and turnover of surface immunoglobulins

TLDR

Immunoglobulins on B‑cell membranes are mobile within the lipid bilayer, a property shared by other membrane antigens that may influence lymphocyte immune function. Treatment with divalent anti‑Ig antibodies causes mobile Ig to cluster into spots that merge into polar caps, a process that persists despite metabolic inhibition but is suppressed by cold, resulting in transient loss of surface Ig followed by rapid resynthesis that restores and even increases Ig density on the membrane.

Abstract

Abstract The immunoglobulins which are present on the membrane of B lymphocytes of different species are mobile in the plane of the membrane itself. This mobility results in the formation of spots of immunoglobulins when the cells are treated with divalent antibodies against immunoglobulins; the spots then combine into polar caps. The process of spot formation is not inhibited by different substances that inhibit cell metabolism, but is markedly inhibited in the cold. The formation of caps is followed by the disappearance of immunoglobulins from the cell membrane but, if the cells are not left in contact with the anti‐immunoglobulin antiserum, there is a rapid resynthesis of new membrane immunoglobulins. It appears that the percentage of lymphocytes that resynthesize immunoglobulins is identical to that of cells originally carrying immunoglobulins, but the amount of surface immunoglobulins of each cell is increased after antiserum treatment. Many other membrane antigens behave in a similar way after treatment with the corresponding antisera; the possible role of the mobility of membrane proteins for the immunological functions of lymphocytes is discussed.