Detection of normal B-cell precursors that give rise to colonies producing both kappa and lambda light immunoglobulin chains.
The pre-B-cell cloning assay is an in vitro differentiation system in which B-lymphocyte precursors expand and generate colonies containing immunoglobulin-secreting cells. Analysis of surface characteristics, growth requirements, and kinetics suggested that these cells represent early stages of the B-cell differentiation pathway. Here we describe a modification of the assay, which allowed us to determine the differentiative potential of these clonable pre-B cells. Using a nitrocellulose protein-transfer technique, we studied immunoglobulin light chain expression in colonies derived from fetal mouse liver B-cell precursors; in particular, we explored whether the B-cell precursors are already committed to the expression of a particular light chain gene at the initiation of culture. Our results show that fetal liver-derived B-cell progenitors generate colonies in vitro that secrete kappa and lambda light chains at a ratio similar to that found in colonies derived from adult splenic B cells. Further, we document the existence of colonies that are derived from single cells and that simultaneously secrete both types of light chains. This indicates that the progenitors of (kappa + lambda)-producing colonies are light chain-uncommitted at the initiation of culture. These cells are able to rearrange their light chain genes in vitro and differentiate along the B-cell pathway to form colonies secreting both kappa and lambda chains.
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D002999:Clone Cells / Q000276:immunology; D003114:Colony-Forming Units Assay; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D007145:Immunoglobulin kappa-Chains / Q000096:biosynthesis* / Q000235:genetics; D007146:Immunoglobulin lambda-Chains / Q000096:biosynthesis* / Q000235:genetics; D008099:Liver / Q000166:cytology / Q000196:embryology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA
D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains