Unique characteristics of lacrimal glands as a part of mucosal immune network: high frequency of IgA-committed B-1 cells and NK1.1+ alphabeta T cells.
OBJECTIVE
Immunologic characterization of IgA-committed B-1 and B-2 cells, and unique subsets of T cells isolated from the murine lacrimal gland (LG), the primary exocrine tissue for the ocular surface, which is considered to be a part of the mucosal immune system.


METHODS
Single cells were obtained from LGs of C57BL/6 mice by the enzyme dissociation method using collagenase type IV. Samples underwent flow cytometric analysis to characterize the unique subsets of T and B cells. To test the effectiveness of ocular vaccination, mice were immunized ocularly or nasally with cholera toxin (CT; 10 microg/mouse) suspended in phosphate-buffered saline. Antigen-specific immune responses were determined by isotype and CT-specific enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot (ELISPOT) assay.


RESULTS
When mononuclear cells (MC) isolated from LG samples were examined by flow cytometry, approximately 28% of cells were characterized as B220+ B cells. Because surface IgA+ (sIgA+) B cells develop from B-1 and B-2 lineages, it was important to examine which subset of B cells gives rise to LG sIgA+ B cells. Examination of the MC isolated from LG samples showed that approximately 4% of cells were sIgA+ B cells. Furthermore, nearly all these sIgA+ B cells (97.5%) belonged to the B-1 lineage, especially the B-1a cell line (B220low, CD5+). Of the isolated CD3+ T cells, 75% were alpha(beta) and 25% were gamma(delta)T-cell receptor positive. The proportion of NK1.1+ alpha(beta) T cells was higher (3%) in LG samples than in submandibular gland samples (0.5%). Ocular immunization with CT-induced antigen-specific mucosal (e.g., found in tear-wash and saliva samples) and systemic (e.g., serum) immune responses. The magnitude of antigen-specific antibody responses was comparable to those induced by nasal immunization.


CONCLUSIONS
These results show that LG contains unique subsets of B (e.g., sIgA+ B-1 cells) and T (e.g., NK1.1+ alpha(beta)T cells) cells. Furthermore, as a part of the mucosal immune barrier, the LG is an important immunologic tissue for the ocular surface.
Saitoh-Inagawa
W
W
Department of Mucosal Immunology, Research Institute of Microbial Diseases, Osaka University, Japan.
Hiroi
T
T
Yanagita
M
M
Iijima
H
H
Uchio
E
E
Ohno
S
S
Aoki
K
K
Kiyono
H
H
D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D000941:Antigens / Q000378:metabolism*; D000950:Antigens, Ly; D000954:Antigens, Surface; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D019070:Cell Lineage; D002772:Cholera Toxin / Q000008:administration & dosage; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D018928:Immunity, Mucosal / Q000276:immunology*; D007071:Immunoglobulin A, Secretory / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D007132:Immunoglobulin Isotypes / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D007765:Lacrimal Apparatus / Q000276:immunology*; D037181:Lectins, C-Type; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D000941:Antigens; D000950:Antigens, Ly; D000954:Antigens, Surface; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; C527211:Klrb1c protein, mouse; D037181:Lectins, C-Type; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D002772:Cholera Toxin