Identification by Peroxidase Staining of Monocytes in Surface Immunofluorescence Tests

Abstract

Surface immunoglobulins (S.Ig) ² on human lymphocytes have been widely studied in the last few years, mainly with surface immunofluorescence (IF) tests. These studies have led to somewhat contradictory results (reviewed in 1) and most discrepancies are likely explained by methodological reasons since S.Ig detection is exposed to a number of pitfalls (2). Monocytes represent an important source of potential errors. They bind serum IgG by their Fc receptor and therefore stain with conjugated antisera to γ-, κ- and λ-immunoglobulin chains. In addition some monocytes are able to bind rabbit IgG used as reagents and show positivity in IF tests whatever the specificity of the conjugate is. Two approaches may be used in order to avoid erroneous interpretation due to monocytes, either the use of cell suspensions free of monocytes or the identification of monocytic cells.