Differences of immunoglobulin secreting cells in bone marrow from those in circulation: relevance to their development.

The surface markers of immunoglobulin secreting cells (ISC) in bone marrow and peripheral blood were analysed. Circulating ISC bear surface Ig and Ia-like antigens. However, these markers were not detectable on ISC in bone marrow. Fc and complement receptors were not present on circulating ISC. The areas of plaques corresponding to Ig secretion by bone marrow cells were always larger than those of peripheral blood cells. Although the majority of ISC were typical plasma cells, plasmacytoid lymphocytes were observed in peripheral blood. These findings seem to indicate that ISC in the peripheral blood are less advanced in their differentiation and maturation pathway from B lymphocytes to plasma cells than those in bone marrow. ISC in mesenteric lymph nodes exhibited nearly the same phenotype as peripheral cells.