A Primitive T Cell-Independent Mechanism of Intestinal Mucosal IgA Responses to Commensal Bacteria
Andrew J. Macpherson,
1*
Dominique Gatto,
1
Elizabeth Sainsbury,
2
Gregory R. Harriman,
3
Hans Hengartner,
1
Rolf M. Zinkernagel
1
The immunoglobulin A (IgA) is produced to defend mucosal
surfaces from environmental organisms, but host defenses against the
very heavy load of intestinal commensal microorganisms are poorly
understood. The IgA against intestinal commensal bacterial antigens was
analyzed; it was not simply "natural antibody" but was specifically
induced and responded to antigenic changes within an established gut
flora. In contrast to IgA responses against exotoxins, a significant
proportion of this specific anti-commensal IgA induction was through a
pathway that was independent of T cell help and of follicular lymphoid
tissue organization, which may reflect an evolutionarily primitive form
of specific immune defense.
1 Institute of Experimental Immunology,
Universitätsspital, Schmelzbergstrasse 12, CH8091,
Zürich, Switzerland.
2 GKT School of Medicine,
Bessemer Road, London SE5 9PJ, UK.
3 Centocor, 200 Great
Valley Parkway, Malvern, PA 19355, USA.
*
To whom correspondence should be addressed. E-mail:
amacpher{at}pathol.unizh.ch
