A general method for enumerating single cells secreting antigen: albumin-secreting hepatocytes detected as plaque-forming cells.

Sheep erythrocytes, artificially coated with purified antibody specific for mouse serum albumin (anti-MSA Ab-E) were agglutinated and lysed by mouse serum albumin. Mouse liver cells, plated with anti-MSA Ab-E formed hemolytic plaque in a modified plaque-forming cell (PFC) assay. The same cells tested with anti-MSA Ab-E did not rosette in modified immunocyto-adhesion assay. Thus, liver cells secreted molecules (albumin) which were not detectable on the cell membrane. This PFC assay with Ab-E is probably a general method for enumerating antigen-secreting cell.