CCL3L3 (C-C motif chemokine ligand 3 like 3) is a chemokine located on chromosome 17 that functions as an inflammatory mediator involved in immune cell recruitment and host defense. The gene is highly homologous to CCL3L1, sharing identical sequences in critical regions 1. CCL3L3 is rapidly upregulated in monocytes following pathogen-associated stimuli, particularly in response to bacterial lipopolysaccharide and Chlamydia trachomatis infection, functioning as part of the innate immune response 23. However, CCL3L3 demonstrates context-dependent roles: during C. trachomatis coinfection, elevated CCL3L3 expression enhances HIV-1 replication in CD4 T cells, yet exogenous CCL3L1/CCL3L3 paradoxically reduces HIV-1 infection in healthy cells 3. CCL3L3 copy number variation (CNV) significantly impacts disease susceptibility; CCL3L3-null status is strongly associated with systemic lupus erythematosus (SLE) susceptibility (OR>18, p<0.0001) 4. The gene is also implicated in other autoimmune conditions: it serves as a potential biomarker in ankylosing spondylitis and systemic sclerosis, correlating with natural killer cell-mediated cytotoxicity 5, and shows elevated expression in preterm placentas during warm season pregnancies, suggesting environmental modulation of inflammatory pathways 6. Functionally, CCL3L3 participates in NF-κB signaling and chemokine pathway regulation 7.