Germinal center cells: antigen specificity, heavy chain class expression and evidence of memory.

Abstract

Germinal centers arise as discrete sites of B-cell differentiation in B cell areas of lymphoid tissue after antigenic stimulation. In the mouse germinal center cells can be confidently identified in cell suspensions as PNAhi B cells, binding 10–30 times as much PNA as other B and T cells or plasma cells (PNAlo) and are furthermore characterized by a lack of surface IgD1–3. In Peyer’s patches the majority of germinal center cells bear the IgA isotype whereas in lymph nodes the predominant isotype after primary stimulation is IgM2,3. Surface IgG expression was observed after secondary stimulation of the lymph nodes, suggesting an important role for the germinal center in heavy chain class switching2. The germinal center population contains the majority of antigen-binding cells2 and in a study on the localization of germinal center cells it has been demonstrated that they lack normal migratory and homing mechanisms most small lymphocytes possess4. Using two color FACS analysis we studied the stages in germinal center development and looked at the memory potential of these cells using an adoptive transfer system.