B6-Igl KO Mouse

Antibodies, or immunoglobulins (Igs), are crucial components of the immune system, specifically recognizing and neutralizing foreign pathogens. They bind selectively to antigens, triggering an immune response. Upon antigen entry, B cells differentiate into plasma cells, which subsequently synthesize and secrete antibodies. Beyond neutralization, antibodies engage Fc receptors on T cells, macrophages, mast cells, and complement components, thereby facilitating antigen clearance through antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), or modulating the activation of classical pathways ^[1-2]. The immunoglobulin (Ig) structure comprises two identical light chains (L) and two identical heavy chains (H), forming a classical Y-shaped structure stabilized by interchain disulfide bonds, noncovalent interactions, and hinge regions ^[2-3]. Each heavy and light chain contains a variable region and a constant region; the variable regions are essential for recognizing and binding specific antigens. Antibody diversity arises largely from sequence variations within these variable regions, enabling B cells to detect a vast array of antigens. In mammals, immunoglobulins contain both kappa (κ) and lambda (λ) light chains. Although there are no significant functional differences between these two light chain types, individual B cells express only one type. The ratio of κ- to λ-expressing B cells varies by species: in humans, this ratio is approximately 2:1, whereas in mice, it is about 20:1, with the majority of mouse B cells expressing only κ light chains ^[4]. The gene segments encoding antibody structures (Ig motifs) are spatially separated in embryonic cells, predominantly comprising variable (V) and constant (C) regions. The highly variable V region includes variable (V), diversity (D), and joining (J) genes, which undergo random DNA rearrangements to connect with the relatively conserved C region, thereby encoding diverse antibody types ^[5]. Notably, antibody light chains lack D genes and are composed solely of V, J, and C gene fragments.

The B6-Igl KO mouse is a knockout model targeting the gene segment encoding the λ light chain. Through gene editing, the sequences encoding the V, J, and C regions of the mouse λ light chain (Igl) locus are completely ablated, resulting in the absence of B cells expressing immunoglobulin light chain λ. Consequently, B6-Igl KO mice serve as a valuable tool for investigating B cell development and function, generating κ light chain-only mouse antibodies, elucidating the role of the λ light chain in specific immune responses or autoimmune diseases, and exploring antibody diversity, immune regulatory mechanisms, and potential therapeutic strategies ^[6].