Clone REAL335 is an antibody fragment derived from the full CD37 antibody molecule. It displays no binding to Fc receptors. The recombinantly engineered antibody fragments are multimerized to form the REAlease Complex to bind markers with high avidity.

Clone REAL335 recognizes the human CD37 antigen, a multi-pass membrane protein which is also known as tetraspanin-26 (Tspan-26). CD37 is a member of the transmembrane 4 superfamily of tetraspanin proteins, which consist of four potential membrane-spanning regions, two extracellular loops, and two short intracytoplasmic tails. Although most tetraspanins are ubiquitous proteins, CD37 expression is nearly exclusively limited to mature B cells and B cell–derived lymphoid malignancies. B cell early progenitors, T cells, natural killer cells, and myeloid cells exhibit only minimal amounts of membrane-associated CD37. In innate immunity, CD37 interacts with pattern recognition receptor Dectin-1, stabilizing Dectin-1 at the macrophage cell surface, and negatively regulating proinflammatory cytokine secretion following ligand recognition. Adaptive humoral immune responses are also perturbed by CD37 ablation. In cellular immunity, CD37 negatively regulates T cell proliferation. In antigen-presenting cells, CD37 associates with MHC class II at the cell surface and has been shown to negatively regulate antigen presentation. CD37 has recently attracted interest as a target for monoclonal antibodies with therapeutic potential in B cell malignancies.

The REAlease Kits consist of the respective fluorochrome-conjugated REAlease Complexes and the REAlease Support Kit for removal of the REAlease Complexes and optional relabeling with different fluorochrome-conjugated REAlease Complexes.