TY - JOUR
T1 - Immunization of newborn mice accelerates the architectural maturation of lymph nodes, but AID-dependent IgG responses are still delayed compared to the adult
AU - Munguía-Fuentes, Rosario
AU - Yam-Puc, Juan Carlos
AU - Silva-Sánchez, Aarón
AU - Marcial-Juárez, Edith
AU - Gallegos-Hernández, Isis Amara
AU - Calderón-Amador, Juana
AU - Randall, Troy D.
AU - Flores-Romo, Leopoldo
N1 - Publisher Copyright:
© 2017 Munguía-Fuentes, Yam-Puc, Silva-Sánchez, Marcial-Juárez, Gallegos-Hernández, Calderón-Amador, Randall and Flores-Romo.
PY - 2017/1/19
Y1 - 2017/1/19
N2 - Lymph nodes (LNs) have evolved to maximize antigen (Ag) collection and presentation as well as lymphocyte proliferation and differentiation-processes that are spatially regulated by stromal cell subsets, including fibroblastic reticular cells (FRCs) and follicular dendritic cells (FDCs). Here, we showed that naïve neonatal mice have poorly organized LNs with few B and T cells and undetectable FDCs, whereas adult LNs have numerous B cells and large FDC networks. Interestingly, immunization on the day of birth accelerated B cell accumulation and T cell recruitment into follicles as well as FDC maturation and FRC organization in neonatal LNs. However, compared to adults, the formation of germinal centers was both delayed and reduced following immunization of neonatal mice. Although immunized neonates poorly expressed activation-induced cytidine deaminase (AID), they were able to produce Ag-specific IgGs, but with lower titers than adults. Interestingly, the Ag-specific IgM response in neonates was similar to that in adults. These results suggest that despite an accelerated structural maturation of LNs in neonates following vaccination, the B cell response is still delayed and reduced in its ability to isotype switch most likely due to poor AID expression. Of note, naïve pups born to Ag-immunized mothers had high titers of Ag-specific IgGs from day 0 (at birth). These transferred antibodies confirm a mother-derived coverage to neonates for Ags to which mothers (and most likely neonates) are exposed, thus protecting the neonates while they produce their own antibodies. Finally, the type of Ag used in this study and the results obtained also indicate that T cell help would be operating at this stage of life. Thus, neonatal immune system might not be intrinsically immature but rather evolutionary adapted to cope with Ags at birth.
AB - Lymph nodes (LNs) have evolved to maximize antigen (Ag) collection and presentation as well as lymphocyte proliferation and differentiation-processes that are spatially regulated by stromal cell subsets, including fibroblastic reticular cells (FRCs) and follicular dendritic cells (FDCs). Here, we showed that naïve neonatal mice have poorly organized LNs with few B and T cells and undetectable FDCs, whereas adult LNs have numerous B cells and large FDC networks. Interestingly, immunization on the day of birth accelerated B cell accumulation and T cell recruitment into follicles as well as FDC maturation and FRC organization in neonatal LNs. However, compared to adults, the formation of germinal centers was both delayed and reduced following immunization of neonatal mice. Although immunized neonates poorly expressed activation-induced cytidine deaminase (AID), they were able to produce Ag-specific IgGs, but with lower titers than adults. Interestingly, the Ag-specific IgM response in neonates was similar to that in adults. These results suggest that despite an accelerated structural maturation of LNs in neonates following vaccination, the B cell response is still delayed and reduced in its ability to isotype switch most likely due to poor AID expression. Of note, naïve pups born to Ag-immunized mothers had high titers of Ag-specific IgGs from day 0 (at birth). These transferred antibodies confirm a mother-derived coverage to neonates for Ags to which mothers (and most likely neonates) are exposed, thus protecting the neonates while they produce their own antibodies. Finally, the type of Ag used in this study and the results obtained also indicate that T cell help would be operating at this stage of life. Thus, neonatal immune system might not be intrinsically immature but rather evolutionary adapted to cope with Ags at birth.
KW - Class-switched antibodies
KW - FDCs
KW - FRCs
KW - Germinal centers
KW - Immunization at birth
KW - Neonates
UR - http://www.scopus.com/inward/record.url?scp=85012236117&partnerID=8YFLogxK
U2 - 10.3389/fimmu.2017.00013
DO - 10.3389/fimmu.2017.00013
M3 - Artículo
AN - SCOPUS:85012236117
SN - 1664-3224
VL - 8
JO - Frontiers in Immunology
JF - Frontiers in Immunology
IS - JAN
M1 - 13
ER -