1. A method of manufacturing an isolated labeling reagent, wherein said method comprises the steps of: a) cleaving an intact anti-region antibody with an enzyme to generate Fab fragments; b) isolating said anti-region Fab fragments of step a); c) contacting a matrix comprising intact immunoglobulin proteins or fragments that selectively bind anti-region Fab fragments with a solution comprising said anti-region fragments of step b) wherein said anti-region Fab fragments are immobilized on said matrix; d) contacting said matrix of step c) with a solution comprising a fluorophore label that contains a reactive group; e) washing said matrix of step d) to remove unbound label, and; f) eluting said labeling reagent from said matrix whereby said isolated labeling reagent is manufactured.