Cheryl A. Skandera

A comparison of lymphocyte subset distribution in rat lacrimal glands with cells from tissues of mucosal and non-mucosal origin

The subset distribution of lymphocyte populations isolated from rat lacrimal glands (LG) was compared with those from tissues of both mucosal and non-mucosal origin. In spleen (SPL), mesenteric (MLN) and cervical lymph node (CLN) populations the percentages of cells bearing W3/13 (pan T) and OX19 (pan T) were greater than the percentages obtained for cells bearing the OX7 (Thy-1) marker. In contrast, for lacrimal (LG), salivary (SG) and mammary gland (MG) populations, cells bearing OX7 predominated over those bearing the W3/13 and OX19 markers, with the exception of day 1 post-partum MG tissue which displayed equal numbers of OX7 and OX19 cells. Except for MG, in which OX8 (T non-helper) predominated over W3/25 (T helper) populations, the proportions of these two subsets in the other tissues were generally similar. Analysis of SPL and LG cells for coexpression of OX7 with OX19 or L chain indicated that significant percentages of OX7 bearing cells also expressed T or B cell markers. However, the higher values noted for the OX7 population in LG were not attributable to increased numbers of cells coexpressing pan T or B cell markers. These findings show that lymphocyte subset distribution in LG and other glandular mucosal tissues is distinct from that of non-mucosal tissues, in that mucosal tissues contain a predominance of cells bearing the Thy-1 (OX7) phenotype.

Lymphocyte Lineages at Mucosal Effector Sites: Rat Salivary Glands

Development of T cell lineages and the role of the thymus as a source of immature T cells in parotid (PG) and submandibular salivary glands (SMG) were studied in Fischer 344 rats using the Thy-1/CD45RC/RT6 expression model. In addition, the phenotypes of salivary gland lymphocytes were compared with other conventional and extrathymic populations. PG mononuclear cells consisted of T cells (38%), B cells (29%), and NK cells (4%). SMG had 19% T cells, 7% B cells, 37% NK cells, and an unusual population of CD3−/RT6+ cells. In comparison with lymph node (LN), both PG and SMG were enriched in immature (Thy-1+) and activated (Thy-1−/CD45RC−/RT6−) T cells. Unchanged percentages of Thy-1+ T cells in PG and SMG following short-term adult thymectomy indicated that immature salivary gland T cells had an extrathymic source. In contrast, thymectomy eliminated LN recent thymic emigrants. SMG had T cells with characteristics of extrathymic populations, expressing TCRγδ+ (28%), the CD8αα homodimer (11%), and NKR-P1A (66%). Many SMG T cells expressed integrin αEβ7. PG T cells resembled those isolated from LN in respect to TCR and CD8 isoform usage, but were enriched in αEβ7+ T cells and in NKT cells. Thus, salivary gland mononuclear cells are composed of a variety of subpopulations whose distributions differ between SMG and PG and are distinct from LN. These studies provide a basis for further investigation of regionalization in the mucosal immune network and are relevant to the design of vaccine regimens and intervention during pathological immune processes.

Evidence for Migration of IgA Bearing Lymphocytes between Peripheral Muscosal Sites

Abstract The mouse adoptive transfer system was employed to compare the homing properties of labeled mammary gland, mesenteric lymph node and peripheral lymph node cell populations. The homing properties of mammary gland cells to lacrimal glands, salivary glands and small intestine was similar to mesenteric lymph node cells. Preliminary evidence suggests that an IgA-bearing population of mammary gland cells was responsible for homing. The data suggests that cell traffic between peripheral mucosal sites is an additional mechanism controlling the expression of IgA antibodies in secretions.

The effect of immunization route and sequence of stimulation on the induction of IgA antibodies in tears.

The capacity of ocular/topical (OT) or gastrointestinal (GI) immunization routes alone or sequentially to elicit and maintain tear IgA antibody responses was assessed in the rat model. Seven days after each biweekly immunization with dinitrophenylated type-III pneumococcal vaccine, the IgA antibody levels in serum, saliva and tears were measured. All groups generally lacked serum IgA responses and eventually possessed similar salivary response frequencies with OT, OT/GI and GI groups showing a tendency for increased salivary IgA antibody levels. Tear IgA antibody responses in all groups were comparable after the third immunization. Subsequently the OT group displayed a gradual reduction in response frequency with a significant drop in IgA levels after the sixth immunization. The OT/GI group maintained tear IgA response frequencies while displaying a significant increase in tear IgA antibody levels; the GI and GI/OT groups maintained tear IgA antibody responses. These data demonstrate that the immunization route and sequence of stimulation have a marked impact on the expression of IgA anti-DNP antibodies in tears.

Development of T cell lineages in rat lacrimal glands

Purpose. The purpose of this study was to examine T cell development in rat lacrimal glands, determine whether the thymus is the source of immature T cells in this tissue and compare lacrimal gland T lymphocytes with other T cell subpopulations. Methods. Mononuclear cells were isolated from lacrimal glands of normal or thymectomized female Fischer 344 rats and stained for flow cytometric analysis. Results. The lacrimal gland T lymphocyte population included large percentages of cells with an activated phenotype and also subpopulations of immature, naive and memory T cells. The numbers of immature (Thy-1 +) lacrimal gland T cells were unchanged following short-term adult thymectomy. In comparison, spleen had large percentages of naive T cells, only a small subpopulation of activated T cells, and similar percentages of immature (Thy-1 +) T cells, which were nearly eliminated after thymectomy. Lacrimal gland T cells had small subpopulations of TCR?d + and CD8aa + T cells, a large subpopulation of NKT cells and many integrin aEß7 + T cells. Conclusions. Lacrimal gland T cells are composed of a variety of subpopulations whose composition is distinct from splenocytes. The marked reduction of immature splenic T cell percentages eleven days after adult thymectomy indicates that these cells were mostly derived from thymic precursors. In contrast, the unchanged percentages of immature lacrimal gland T cells following thymectomy indicate that they may have an extrathymic source. These studies provide a foundation for further investigation into the cellular basis of lacrimal gland immunobiology.

Rat Lacrimal Glands Contain Activated and Resting Mature T Cells, Recent Thymic Emigrants, and Possibly Extrathymic Populations

Lacrimal glands (LG) possess both transient and stationary lymphocyte populations, distinct from those in peripheral lymphoid sites, which regulate and effect humoral and cell-mediated immune responses contributing to the protection of ocular surfaces.1,2 Further, lacrimal glands are sites of lymphocytic infiltration in inflammatory disorders such as Sjogren’s syndrome. Earlier work has established that rat lacrimal gland lymphocytes display a distinct phenotypic profile compared to nonmucosal lymphoid tissues.3,4 Of particular interest is the presence of lymphocytes expressing Thy-1, which, in the rat, is found on immature B and T lymphocytes in bone marrow and thymus5,6 as well as on their recently released progeny in the periphery. The Thy-1 molecule is lost with increasing maturity.7,8 In the case of T cells, developmental stages, including immature recent thymic emigrants (RTE), mature common peripheral T cells (CPT), and activated T cells that have recently encountered antigen, can be identified on the basis of size and expression of Thy-1 and CD45RC.7,8

Regulation of Lacrimal Gland Immune Responses

The purpose of this review is: (1) to consider the relationship of the lacrimal gland to the mucosal network and general factors regulating lacrimal gland immune responses, (2) to present current data from selected studies on lacrimal gland immunoregulation, and (3) to discuss the future directions of lacrimal gland immunobiology and regulation.

Characterization and Mitogenic Responsiveness of Murine Mammary Gland Mononuclear Cells

Lymphocyte traffic from subcompartments of intestinal mucosal associated lymphoid tissue (MALT) to mammary (1), salivary (2) and lacrimal (3) glands is a characteristic feature of the mucosal network. With respect to glandular structures it is not clear whether these compartments function simply by providing an environment into which precommitted B cells migrate and terminally differentiate or whether they also contain the functional cell populations necessary to interact in the generation of local antibody responses. Numerous studies have demonstrated the presence of viable lymphocyte populations in the colostrum, milk and mammary secretions for a variety of animal species (4–17). These cell populations have been isolated and studied with respect to cell surface markers (10,15–17) and responsiveness to mitogens (4,6–9,11–14). However, it is not known whether the cells which were characterized in these studies are expressed only in secretions or represent the total mononuclear cell component of the gland. Since little is known about isolated glandular cell populations and because the mouse is a well-defined model for studying B cell ontogeny, T and B cell interactions and cell traffic, the present report examines the morphological characteristics, membrane marker distribution and mitogen responsiveness of mouse mammary gland cell populations.