Interleukin-4 is a neutrophil activator.
We investigated the ability of the lymphokine, interleukin-4 (IL-4), to function as a neutrophil (PMN) activator. IL-4 enhanced PMN-mediated killing of opsonized bacteria (by up to 91.6% at 3 units of IL-4; p less than 0.05). IL-4 was a weak secondary granule secretagogue and did not by itself generate a respiratory burst. However, IL-4 did increase in a dose-dependent fashion the respiratory burst mediated by the peptide formyl-methionyl-leucyl-phenylalanine (10(-7) mol/L). Maximal potentiation of PMN activity occurred at 100 units of IL-4 (6.3 nmol superoxide produced without IL-4 to 9.8 nmol at 100 units; p less than 0.01). Enhancement of the respiratory burst was not a generalized phenomenon, since IL-4 did not potentiate the respiratory burst mediated by either phorbol myristate acetate, calcium ionophore A23187, or zymosan-treated serum. Similarly, IL-4 potentiated the formyl-methionyl-leucyl-phenylalanine-stimulated secretion of both lysozyme (40.2%) and beta-glucuronidase (108.2%). Finally, IL-4 was demonstrated to enhance the ability of PMN to phagocytose sheep erythrocytes opsonized with rabbit IgG (by up to 94.2% at 30 units of IL-4). This increased phagocytosis correlated with the recruitment of a population of PMNs that did not phagocytose targets in the absence of IL-4. In conclusion, IL-4 enhanced neutrophil-mediated bactericidal activity. This increase may have occurred secondary to the stimulation of phagocytosis by IL-4 or by potentiation of degranulation and the respiratory burst.
Boey
H
H
Allergy Division, New England Medical Center, Boston, MA 02111.
Rosenbaum
R
R
Castracane
J
J
Borish
L
L
D001770:Blood Bactericidal Activity; D003594:Cytoplasmic Granules / Q000201:enzymology; D005966:Glucuronidase / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D015847:Interleukin-4; D007378:Interleukins / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008213:Lymphocyte Activation; D009113:Muramidase / Q000097:blood; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology*; D010587:Phagocytosis; D013481:Superoxides / Q000096:biosynthesis / Q000097:blood
D007378:Interleukins; D013481:Superoxides; D015847:Interleukin-4; D007770:L-Lactate Dehydrogenase; D009113:Muramidase; D005966:Glucuronidase