Antibody clone TX41 is a monoclonal antibody against mouse CLM-8, also known as CD300a. The CD300 family of receptors is an evolutionary conserved receptor family that belongs to the Ig superfamily and is expressed predominantly by the myeloid lineage. In mice, nine members have been reported with different nomenclature systems, such as myeloid-associated Ig-like receptor (MAIR), leukocyte mono-Ig-like receptor (LMIR), DC-derived Ig-like receptor (DIgR), and CMRF-35-like molecule (CLM). CD300 molecules act as either activating or inhibitory receptors through interactions with adaptor molecules, such as PAD12, DAP10, and FcRγ. In recent years data have shown that eosinophils express various Ig superfamily receptors that regulate key checkpoints in their biology including maturation, transition from the bone marrow to the peripheral blood, migration, adhesion, survival, and effector functions in response to numerous activating signals such as IL-4, IL-33, and bacteria. CD300a is an inhibitory receptor that is expressed by mast cells, neutrophils, peripheral eosinophils, dendritic cells, macrophages, and B cells. Its inhibitory signal depends on the phosphorylation of tyrosine residues embedded in ITIMs of the cytoplasmic tail and regulate a diverse array of immune cell processes. CD300a recognizes phosphatidylserine and phosphatidylethanolamine, two aminophospholipids exposed on the outer leaflet of dead and activated cells. This provided new insights regarding its role in the modulation of immune functions and in its participation in the host response to several diseases states, such as infectious diseases, cancer, allergy, and chronic inflammatory diseases.