Nature of the union between sheep red blood cells and T lymphocytes.

Calcium ions acting as salt bridges between the receptor on T lymphocytes and the negatively charged sites on sheep red blood cells (SRBC) are probably involved in rosette formation. Evidence to support this hypothesis includes the results of manipulating the ionic concentration of Ca2+free incubation medium and rosette inhibition in the presence of EDTA. Optimal rosette formation occurred when NaCl was the supporting electrolyte and the ionic strength was 100-150 mM. Neither KCl, CaCl2, MgCl2 nor Na2SO4 were effective as supporting electrolytes. SRBC pretreated with neuraminidase showed improved rosette formation of lower ionic strength than control cells.