US Patent 7166423 Direct selection of cells by secretion product

Cells can be labeled with products which they secrete and release in an efficient manner by coupling the cells at their surface to a specific binding partner for the product and allowing the product to be captured by the specific binding partner as it is secreted and released. The product-labeled cells can then be further coupled to suitable labels, if desired, and separated according to the presence, absence, or amount of product.