4 research outputs found
Collective polarization exchanges in collisions of photon clouds
The one-loop "vacuum" Heisenberg-Euler coupling of four electromagnetic
fields can lead to interesting collective effects in the collision of two
photon clouds, on a time scale orders of magnitude faster than one estimates
from the cross-section and density. We estimate the characteristic time for
macroscopic transformation of positive to negative helicity in clouds that are
initially totally polarized and for depolarization of a polarized beam
traversing an unpolarized cloud.Comment: Recapitulates much that is in hep-ph/0402127, with new results in the
last section, and the first section drastically reduced in view of the
previous work of Kotkin and Serbo. Typo corrected in eq. 1
Immunoglobulin A-Mediated Protection against Bordetella pertussis Infection
Infection with Bordetella pertussis, the causative agent of pertussis (whooping cough) in humans, is followed by the production of antibodies of several isotypes, including immunoglobulin A (IgA). Little is known, however, about the role of IgA in immunity against pertussis. Therefore, we studied targeting of B. pertussis to the myeloid receptor for IgA, FcαRI (CD89), using either IgA purified from immune sera of pertussis patients or bispecific antibodies directed against B. pertussis and FcαRI (CD89 BsAb). Both IgA and CD89 BsAb facilitated FcαRI-mediated binding, phagocytosis, and bacterial killing by human polymorphonuclear leukocytes (PMNL) and PMNL originating from human FcαRI-transgenic mice. Importantly, FcαRI targeting resulted in enhanced bacterial clearance in lungs of transgenic mice. These data support the capacity of IgA to induce anti-B. pertussis effector functions via the myeloid IgA receptor, FcαRI. Increasing the amount of IgA antibodies induced by pertussis vaccines may result in higher vaccine efficacy