Rat IgG1 is a subclass of immunoglobulin G (IgG) antibodies commonly found in rats and widely utilized in research due to its stability and adaptability. As part of the adaptive immune system, IgG1 constitutes a significant portion of circulating antibodies in rats. Structurally, it consists of two heavy chains (γ1) and two light chains, forming a Y-shaped molecule with antigen-binding Fab regions and an Fc region that interacts with immune cells. Compared to other IgG subclasses (e.g., IgG2a, IgG2b, IgG2c), Rat IgG1 exhibits relatively weak effector functions, such as low affinity for Fc gamma receptors (FcγRs) and limited complement activation. This makes it less effective in triggering antibody-dependent cellular cytotoxicity (ADCC) or complement-dependent cytotoxicity (CDC), but advantageous in applications where minimizing background immune activation is critical.
Rat IgG1 antibodies are frequently employed in immunoassays (e.g., flow cytometry, ELISA, immunohistochemistry) as detection or blocking reagents. They also serve as popular isotype controls to distinguish specific binding from nonspecific interactions. In therapeutic development, Rat IgG1 scaffolds are sometimes engineered for chimeric or humanized antibodies due to their predictable behavior. Notably, many commercially available monoclonal antibodies targeting cell surface markers (e.g., CD3. CD28) are of the IgG1 subclass. While their limited effector functions can be a drawback in certain therapeutic contexts, this property is often mitigated by coupling with drugs, radiolabels, or adjuvants. Overall, Rat IgG1 remains a cornerstone in biomedical research, balancing specificity with functional versatility.