Regulation of mucosal responses by CD4+ T lymphocytes: effects of anti-L3T4 treatment on the gastrointestinal immune system.
The role of CD4+ T cells in the gastrointestinal (GI) immune system in vivo was studied in mice selectively depleted of this subset by treatment with monoclonal anti-L3T4 (GK1.5) mAb. Treatment of young BALB/c mice with weekly injections of anti-L3T4 mAb resulted in a selective depletion of CD4+ T cells in both IgA effector (lamina propria regions of the intestine; LP) and inductive (Peyer's patch; PP) sites. However, levels of CD3+CD4-CD8+ and CD4-CD8- (double negative) T cells remained constant or increased. When sections of small intestine were assessed for the isotype of Ig-containing cells, normal mice contained predominantly IgA plasma cells with small numbers of IgM and IgG plasma cells while anti-L3T4 treatment dramatically reduced the numbers of IgA plasma cells. When numbers of IgA-producing cells were assessed by the isotype-specific ELISPOT assay, the LPL of anti-L3T4 mAb-treated mice showed an 80% reduction in the number of IgA spot-forming cells. The effect of anti-L3T4 mAb treatment on IgA inductive sites was also studied and this treatment reduced the overall size of PP as well as the germinal centers in this tissue. Although anti-L3T4 treatment depleted CD3+CD4+ T cells in PP, the relative frequency of surface IgA-positive (slgA+) B cells in this tissue did not change. These results show that repeated injection of anti-L3T4 mAb results in a CD4+ T cell deficiency in both IgA inductive (PP) and effector (LP) sites. The depletion of CD4+ T cells resulted in reductions in the numbers of mature IgA plasma cells present in the LP of gut-associated tissues, and reduced the overall size of PP including germinal centers, but did not affect the frequency of sIgA+ B cells in this IgA inductive site.
Department of Oral Biology, University of Alabama, Birmingham 35294.
J
J
Mega
M G
MG
Bruce
K W
KW
Beagley
J R
JR
McGhee
T
T
Taguchi
A M
AM
Pitts
M L
ML
McGhee
R P
RP
Bucy
J H
JH
Eldridge
J
J
Mestecky
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000921:Antibody-Producing Cells / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis / Q000276:immunology*; D017252:CD3 Complex; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016827:CD8 Antigens / Q000032:analysis; D007070:Immunoglobulin A / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000276:immunology*; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D010581:Peyer's Patches / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D016827:CD8 Antigens; D007070:Immunoglobulin A; D011948:Receptors, Antigen, T-Cell