Immunofluorescent Studies of Immunoglobulins in Human Lymphoid Cells in Continuous Culture

Abstract

Immunoglobulin formation was assessed in 19 human lymphoid lines in continuous culture using fluorescein- and rhodamine-labeled antiserums specific for IgG, IgA, IgM heavy chains and κ and λ light chains. Fifteen of these lines demonstrated cytoplasmic localization of one or more heavy and light chain immunoglobulin molecules. In the cell lines which gave positive fluorescent tests only part of the cell population contained detectable immunoglobulins. Both γ- and µ-classes of immunoglobulin heavy chain were identified in the cytoplasm of individual cells of the cell line IM-1, in which both IgG and IgM molecules are synthesized. This finding indicates that in these cells the genetic information for synthesis of two classes of immunoglobulins (IgG and IgM) was expressed. This finding contrasts with the evidence that most normal and malignant immunoglobulin-synthesizing cells in vivo express genetic information for only a single immunoglobulin class. Whether this feature of the cells in culture corresponds to the normal in vivo function of the culture precursor cell(s) or whether it reflects special conditions of culture will have to be answered by further studies.