Cj. Fitzer-attas et al., Fc gamma receptor-mediated phagocytosis in macrophages lacking the Src family tyrosine kinases Hck, Fgr, and Lyn, J EXP MED, 191(4), 2000, pp. 669-681
Macrophage Fc gamma receptors (Fc gamma Rs) mediate the uptake and destruct
ion of antibody-coated viruses, bacteria, and parasites. We examined Fc gam
ma R signaling and phagocytic function in bone marrow-derived macrophages f
rom mutant mice lacking the major Src family kinases ex pressed in these ce
lls, Hck, Fgr, and Lyn. Many Fc gamma R-induced functional responses and si
gnaling events were diminished or delayed in these macrophages, including i
mmunoglobulin (Ig)G-coated erythrocyte phagocytosis, respiratory burst, act
in cup formation, and activation of Syk, phosphatidylinositol 3-kinase, and
extracellular signal-regulated kinases 1 and 2, Significant reduction of I
gG-dependent phagocytosis was not seen in hck(-/-)fgr(-/-) or lyn(-/-) cell
s, although the single mutant lyn(-/-) macrophages did manifest signaling d
efects. Thus, Src family kinases clearly have roles in two events leading t
o Fc gamma R-mediated phagocytosis, one involving initiation of actin polym
erization and the second involving activation of Syk and subsequent interna
lization. Since Fc gamma R-mediated phagocytosis did occur at modest levels
in a delayed fashion in triple mutant macrophages, these Src fan-Lily kina
ses are not absolutely required for uptake of IgG-opsonized particles.