Dr. Kramer et Jj. Cebra, EARLY APPEARANCE OF NATURAL MUCOSAL IGA RESPONSES AND GERMINAL-CENTERS IN SUCKLING MICE DEVELOPING IN THE ABSENCE OF MATERNAL ANTIBODIES, The Journal of immunology, 154(5), 1995, pp. 2051-2062
We have examined the role of passively transferred maternal Abs in the
ontogeny of ''natural'' mucosal IgA responses before weaning of suckl
ing mice by comparing the immune status of gut-associated lymphoid tis
sue (GALT) (Peyer's patches, mesenteric lymph nodes, and lamina propri
a) in 7- to 25-day-old F-1 severe combined immunodeficient (scid)/+ mi
ce generated through reciprocal crosses of C.B17 scid/scid and normal
congenic (+/+) adult mice. We have also examined the ability of prenat
al vs postnatal transfer of maternal immunity to forestall the develop
ment of natural neonatal mucosal IgA responses by swapping litters of
F-1 scid/+ pups at birth between +/+ and scid/scid mothers. Our result
s demonstrate that F-1 scid/+ pups born to or nursed by scid/scid moth
ers undergo an accelerated development of natural IgA responses that i
nclude germinal center reactions in both Peyer's patches and mesenteri
c lymph nodes. These early IgA responses are evident as: 1) increased
frequencies of IgA-producing GALT organ cultures; 2) increased mean Ig
A output by GALT organ cultures; 3) increased frequencies (>1 log) of
IgA-secreting cells from GALT detected by ELlSPOT at 16 days of age; a
nd 4) germinal center development by 17 days of age detected by in viv
o bromodeoxyuridine incorporation. Finally, FAGS analyses of enteric b
acteria isolated from F-1 scid/+ pups and stained for the presence of
surface-bound mouse IgA demonstrate that the bacterial flora is a majo
r target of both maternal secretory IgA and of the earliest IgA Abs pr
oduced in the neonatal GALT of pups deprived of maternal immunity.