lacks_plasma_membrane_part has plasma membrane part precursor B cell Precursor B cells, often abbreviated as pre-B cells, represent an intermediary stage in the development of B cells, the white blood cells that play a crucial role in the body’s adaptive immunity system. They arise from early lymphoid progenitors in the bone marrow, representing a critical point in B cell development between a pro-B cell and an immature B cell. They differ from mature B cells as they still populate the bone marrow and have yet to fully develop the distinctive B cell receptor complex. The primary function of precursor B cells is to undergo proliferation and rearrange their immunoglobulin light chain gene regions which ultimately forms part of the B cell receptor (BCR), an event crucial to B lymphocyte development. This process is closely monitored by the body's quality control mechanisms, ensuring all newly produced B cells have functional (and not self-reactive) receptors. This receptor editing and checking system helps to prevent autoimmune diseases, triggered when immune cells mistakenly attack the body's own cells. Critical mutations required for the maturation of the BCR happen in stages while the cell is a pre-B cell. Pre-B cells are initially characterized as stage called "large pre-B cells," during which proliferation occurs. Additionally, heavy chain recombination is completed and the cell undergoes a checkpoint in which only cells with a functional heavy chain continue to develop. Afterwards, they transition into a "small pre-B cell" phase, where heavy chain rearrangement ends, and light-chain rearrangement begins. Once the B cell receptor is fully formed following heavy and light chain rearrangement, the cell is considered an immature B cell and leaves the bone marrow. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) CALOHA:TS-0819 pre-B cell A precursor B cell is a B cell with the phenotype CD10-positive. ZFA:0009344 BTO:0001133 https://cellxgene.cziscience.com/cellguide/CL_0000817 pro-B cell B cell, CD19-positive IgM immunoglobulin complex Homo sapiens neprilysin