Tissue and T cell distribution of precursor and mature IL-16.
IL-16 is a novel cytokine, which is chemoattractant for CD4+ T cells, macrophages, and eosinophils. Recently, it was reported that IL-16 is synthesized as an approximately 80-kDa precursor molecule, pro-IL-16. Since little is known about the processing and tissue distribution of IL-16 and pro-IL-16, we investigated the distribution of IL-16 mRNA and protein in human lymphoid tissue. Northern blotting identified IL-16 mRNA predominantly in normal lymphoid organs, including PBMC, spleen, and thymus. Immunohistochemistry of human lymph node localized IL-16 protein to lymphocyte cytoplasm within T cell zones and occasionally in lymphocytes in B cell zones. Flow cytometric detection of intracellular IL-16 showed that >70% of CD4+ and CD8+ T cells constitutively expressed IL-16 protein. Western blot analysis of PBMC revealed nearly all of this protein to be approximately 80-kDa pro-IL-16 in unstimulated PBMC, and upon cell activation, the amino terminus of pro-IL-16 is processed into multiple fragments. These results show that pro-IL-16 is widely and constitutively expressed and suggest that the amino terminus of the protein can be processed upon cell activation.
Chupp
G L
GL
Pulmonary Center, Boston University School of Medicine, MA 02118, USA. geoffrey.chupp@yale.edu
Wright
E A
EA
Wu
D
D
Vallen-Mashikian
M
M
Cruikshank
W W
WW
Center
D M
DM
Kornfeld
H
H
Berman
J S
JS
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D006801:Humans; D019410:Interleukin-16 / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000737:chemistry; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000276:immunology; D011498:Protein Precursors / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D019410:Interleukin-16; D011498:Protein Precursors; C105950:interleukin 16 precursor