The Journal of Immunology, Vol 147, Issue 7 2164-2169, Copyright © 1991 by American Association of Immunologists

ARTICLES

Acylation of cell-associated IL-1 by palmitic acid

O Bakouche, JL Moreau and LB Lachman
Department of Cell Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.

To determine whether membrane-associated IL-1 is palmitylated, we labeled LPS-activated human monocytes with [3H]palmitic acid. The plasma membranes were isolated, and the membrane proteins extracted and analyzed simultaneously by SDS-PAGE-autoradiography and Western blot analysis from the same gel. When the monocytes were labeled with [3H]palmitate, 23- and 31-kDa bands were visualized, for membrane- associated IL-1 and its precursor, respectively. The 31- and 23-kDa bands were excised from several gels and rehydrated and analyzed again by SDS-PAGE, autoradiography, and Western blot analysis. The 23- and 31- kDa bands appeared again by both methods. To further investigate membrane-associated IL-1 acylation, human monocytes were labeled with [3H]palmitate, the plasma membranes isolated, and the membrane proteins extracted by CHAPS detergent. Immunoprecipitation of isolated membrane proteins using anti-IL-1 antibodies revealed two bands of 23 and 31 kDa after autoradiography. The studies demonstrate that both membrane- associated IL-1 and the IL-1 precursor are acylated with palmitic acid.