Am. J. Respir. Cell Mol. Biol., Vol 14, No. 1, 01 1996, 95-103.
Effects of integrin clustering on human lung mast cells and basophils
SE Lavens, K Goldring, LH Thomas and JA Warner
Dept. of Physiology and Pharmacology, University of Southampton, Bassett Crescent East, United Kingdom.
The interaction of cells with the extracellular matrix can alter cell
responses and is regulated by integrins on the cell surface. We used
monoclonal antibodies to the VLA-4 integrins CD29 and CD49d followed by an
F(ab')2 fragment of rabbit anti-mouse immunoglobulin G1 to crosslink
integrins on the surface of human lung mast cells and basophils.
Crosslinking either CD29 or CD49d caused a significant histamine release
(HR) from the basophils of most asthmatic donors (10 of 14 for CD49d and 7
of 10 for CD29) (HR = 21 +/- 5%, n = 10, P < 0.005 for CD29 and HR = 19
+/- 4%, n = 14, P < 0.01 for CD49d) yet failed to initiate HR from the
basophils of non-atopic and atopic donors (HR was 1 +/- 0.5% for CD29 and 1
+/- 0.5% for CD49d, n = 10, P = NS). Crosslinking either CD29 or CD49d also
failed to initiate histamine release from human lung mast cells (HR was 1
+/- 1% for CD29 and 2 +/- 1% for CD49d). The basophils of asthmatic donors
responded to 100 and 30 micrograms/ml tissue fibronectin (HR = 12 +/- 2%
and 10 +/- 3% for 100 and 30 micrograms/ml fibronectin, respectively, n =
18, P < 0.05), whereas basophils of nonasthmatic patients again failed
to degranulate (HR was 0 +/- 0.4% and 1 +/- 0.6%, respectively, n = 11, P =
NS). In contrast to the basophil, crosslinking of either CD29 or CD49d
failed to initiate histamine release in human lung mast cells (HR = 1 +/-
1% for CD29 and 2 +/- 1%, n = 15). Human lung mast cells were also
unresponsive to tissue fibronectin (100 and 30 micrograms/ml) (HR = 1 +/-
1%, n = 5). The tyrosine kinase inhibitor, genistein, significantly reduced
CD29- and CD49d-induced HR (inhibition = 83 +/- 7% for CD29 and 77 +/- 6%
for CD49d, n > or = 5, P < 0.05). A second tyrosine kinase inhibitor,
piceatannol, also significantly reduced both CD29- and CD49d- induced HR
(inhibition was 62 +/- 19% for CD29 and 56 +/- 14% for CD49d, n = 7, P <
or = 0.05). Integrin crosslinking also affected the response to a second,
immunoglobulin E (IgE)-dependent stimulus. Both CD29 and CD49d clustering
significantly inhibited anti-IgE-induced histamine release from the human
basophil. Inhibition was 30 +/- 5%, n = 18, P < or = 0.001 for CD29
versus 40 +/- 6% for CD49d. In summary, we have shown that crosslinking the
beta 1 integrins using either monoclonal antibodies or tissue fibronectin
can initiate mediator release from the basophils of asthmatic patients by a
mechanism which appears to be tyrosine kinase-mediated. In addition,
clustering of integrins modulates the response to a second IgE-dependent
signal.
