Rabbit Thymus Research Articles

Morphofunctional changes in rabbit thymus with simultaneous vaccination and disinsection

The work carried out a morphometric study of the thymus of rabbits vaccinated with the associated vaccine against myxomatosis and viral hemorrhagic disease of rabbits (VHD) at a dose of 0.5 ml subcutaneously and treated with an insecticide preparation “Stronghold” (selamectin 6%) at a dose of 0.1 ml / kg at the withers … Chinchilla rabbits, live weight 2-2.5 kg, aged 6-8 months were used as experimental material. In total, 20 animals were examined. The thymus was examined by conventional histological methods. The nature of changes in the morphofunctional parameters of the thymus with the combined use of the investigated factors revealed a dependence on the time of application of the drug “Stronghold” in relation to the vaccine. Our studies on rabbit immunogenesis with simultaneous vaccination against myxomatosis and viral hemorrhagic disease of rabbits (VGBD) and treatment with the Stronghold insecticide with the active ingredient selamectin in the form of a 6% solution did not show significant morphofunctional changes in the thymus with increased stress load on a living organism.

Antilymphocyte/Thymocyte Globulin for the Treatment of Steroid-Refractory Acute Graft-Versus-Host Disease: 20-Year Experience at a Single Center.

Although there is currently no consensus regarding the treatment of steroid-refractory acute graft-versus-host disease (GvHD) after hematopoietic stem cell transplantation (HSCT), antithymocyte globulin (ATG) is one of the most widely used immunosuppressive drugs in this setting. We retrospectively summarized our transplant center’s experience with 35 steroid-resistant acute GvHD patients who were treated with three different ATG preparations. Severe (grade III-IV) acute GvHD was observed either during the posttransplantation period (n= 32) or after donor lymphocyte infusion (n= 3). For secondary treatment of acute GvHD, rabbit Jurkat cell linereactive ATG (ATG Fresenius®) (n= 22), rabbit thymus cell-reactive ATG (Thymoglobulin®) (n= 9) or equine antilymphocyte globulin (ALG) (Lymphoglobulin®) (n= 4) was administered at a dose of 2-10 mg/kg/day for five consecutive days. The median time from the diagnosis of acute GvHD to the first day of infusion of ATG or ALG was 15 days (3-70 days). An overall response was observed in 15 patients (42%), with similar response rates among patients treated with any of the three ATG preparations. The overall survival (OS) of the patients did not increase in any treatment group, though the severity of GvHD and the disease status before HSCT were shown to negatively impact OS. Although responses could be achieved in steroid-refractory acute GvHD using rabbit or horse ATG, survival rates did not increase because of high mortality rates due to infection during treatment.

Diagnostic utility of unidentified precipitin lines (UPLs) in immune precipitation assays

Unidentified precipitin lines (UPLs) are lines in immune precipitin assays which do not characterise with known extractable nuclear antigen (ENA) antibodies. Currently, the clinical significance of UPLs is uncertain.The aim of this study was to determine the clinical and laboratory correlates of UPLs detected over a 3 year period in a regional immunopathology laboratory.A total of 144 patients with UPLs on ENA testing were retrospectively analysed.ENA by counterimmunoelectrophoresis (CIE) was performed on 11,869 patient samples with further characterisation being performed for 1437 positive results. Ten percent of the positive ENAs demonstrated UPLs. The majority of patients with UPLs were female (71%) with an average age of 60 years. Precipitin lines for both continuously growing myeloid cell line K562 and rabbit thymus extract (RTE) were more frequent (47%), compared to K562 only (41%) or RTE only (12%). The most common antinuclear antibody (ANA) patterns associated with UPLs were speckled (29%), homogenous (16%), mixed patterns (14%), with 30% negative ANA and 5% showing cytoplasmic patterns (Golgi, GWB, mitochondrial). Both ANA positive and ANA negative patients with UPLs were generally associated with connective tissue and autoimmune disease with the majority demonstrating a positive association of UPLs with Ro52 and/or Ro60/SSA detected by Euroimmun line immunoassay. UPLs frequently seen with a negative ANA were also identified in renal disease, pulmonary fibrosis/bronchiectasis and malignancy/lymphoma.UPLs have uncertain diagnostic utility at this stage and further work needs to be done to clarify this question. UPLs were found in systemic and organ specific autoimmune disease, renal, pulmonary and neoplastic disorders. UPLs can occur in both ANA positive and ANA negative sera. The nature of the precipitating antigen in UPLs is still obscure.

AB0416 Clinical and immunological association with autoantibodies to cellular antigen in a cohort of 532 sle patients from a single center.

Backgroundautoantibodies (autoabs) to cellular antigens can be associated with specific clinical and immunological subsets of Systemic Lupus Erythematosus (SLE).Objectivesto analize the frequencies of different autoabs detected by counterimmunoelectrophoresis (CIE) and...

Effect of pesticide bendiocarbamate on distribution of acetylcholine- and butyrylcholine-positive nerves in rabbit’s thymus

Many pesticides used in agriculture have a negative effect on organisms. The group of hazardous pesticides includes the cholinesterase inhibitor bendiocarbamate. According to literature, bendiocarbamate has relatively low toxicity in mammals and vertebrates in general, since it does accumulate in their tissues and the cholinesterase activity returns to norm within 24 h after acute exposure. The present study focused on the influence of bendiocarbamate on rabbit thymus after its administration at a dose of 5 mg/kg body weight (BW) for the period of 3 months. The thymus was observed for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE)-positive nerve fibers visualized by histochemical methods. Microscopic findings of BuChE - positive nerve fibers show the same density and the topography by the experimental and the control animals. On the other hand, AChE - positive nerve fibers in experimental animals after administration of bendiocarbamate is only poorly identified, suggesting that bendiocarbamate inhibits AChE but not BuChE.

Use of flow cytometry to develop and characterize a set of monoclonal antibodies specific for rabbit leukocyte differentiation molecules

Flow cytometry was used to identify and characterize monoclonal antibodies (mAbs) that react with rabbit leukocyte differentiation molecules (LDM). Screening sets of mAbs, developed against LDM in other species, for reactivity with rabbit LDM yielded 11 mAbs that recognize conserved epitopes on rabbit LDM orthologues and multiple mAbs that recognize epitopes expressed on the major histocompatibility class I or class II molecules. Screening of mAbs submitted to the Animal Homologues Section of the Eighth Human Leukocyte Differentiation Workshop yielded 7 additional mAbs. Screening of mAbs generated from mice immunized with leukocytes from rabbit thymus or spleen or concanavalin A activated peripheral blood and/or spleen lymphocytes has yielded 42 mAbs that recognize species restricted epitopes expressed on one or more lineages of leukocytes. Screening of the anti-rabbit mAbs against leukocytes from other species yielded one additional mAb. The studies show that screening of existing sets of mAbs for reactivity with rabbit LDM will not be productive and that a direct approach will be needed to develop mAbs for research in rabbits. The flow cytometric approach we developed to screen for mAbs of interest offers a way for individual laboratories to identify and characterize mAbs to LDM in rabbits and other species. A web-based program we developed provides a source of information that will facilitate analysis. It contains a searchable data base on known CD molecules and a data base on mAbs, known to react with LDM in one or more species of artiodactyla, equidae, carnivora, and or lagomorpha.

Bendiocarbamate induced structural alterations in rabbit thymus after experimental peroral administration

In this study histological structure of rabbit thymus after bendiocarbamate (2,3–isopropyledene–dioxyphenyl methylcarbamate) administration was studied. Bendiocarbamate was perorally administered for 90 days. At Day 3, 10, 20, 30, 60, 90 morphometric analysis was realized. Quantitative evaluation showed that in the control group thymus cortex forms 57.94 ± 7.10% and medulla 35.94± 7.38%. In almost all experimental groups significantly higher relative volume of cortex and lower relative volume of medulla was detected. Detail morphometric analysis found that the number of thymocytes per constant area and the diameter of tymocytes was decresed after bendiocarbamate administration. The number and diameter of reticular cells was not affected. Results of this study suggest negative effect of bendiocarbamate on the formation of thymus structures.

Novel Binding Epitope for Helicobacter pylori Found in Neolacto Carbohydrate Chains: STRUCTURE AND CROSS-BINDING PROPERTIES

Helicobacter pylori is a bacterium that colonizes the stomach of a majority of the global human population causing common gastric diseases like ulcers and cancer. It has an unusually complex pattern of binding to various host glycoconjugates including interaction with sialylated, sulfated, and fucosylated sequences. The present study describes an additional binding epitope comprising the neolacto internal sequence of GlcNAcbeta3-Galbeta4GlcNAcbeta. The binding was detected on TLC plates as an interaction with a seven-sugar ganglioside of rabbit thymus. The glycolipid was purified and characterized as Neu5Gcalpha3Galbeta4GlcNAcbeta3Galbeta4GlcNAcbeta3-Galbeta4Glcbeta1Cer with less than 10% of the fraction carrying a repeated lacto (type-1) core chain, Galbeta3Glc-NAcbeta3Galbeta3GlcNAcbeta. After stepwise chemical and enzymatic degradation and structural analysis of products the strongest binder was found to be the pentaglycosylceramide GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1-Cer, whereas the hexa- and tetraglycosylceramides were less active, and the trihexosylceramide was inactive. Further studies revealed that the terminal GlcNAcbeta of the pentaglycosylceramide may be exchanged for either GalNAcbeta3, GalNAcalpha3, or Galalpha3 without loss of the activity. Calculated minimum energy conformers of these four isoreceptors show a substantial topographical similarity suggesting that this binding is a result of a molecular mimicry. Although the glycoconjugate composition of human gastric epithelial cells is not known in detail it is proposed that repeating N-acetyllactosamine units of glycoconjugates may serve as bacterial attachment sites in the stomach.

Autoimmune responses to proliferating cell nuclear antigen multiprotein complexes involved in cell proliferation are strongly associated with their structure and biologic function in patients with systemic lupus erythematosus.

To analyze the reaction of lupus sera with proliferating cell nuclear antigen (PCNA) multiprotein complexes (PCNA complexes), which are part of the protein machinery involved in cell proliferation. PCNA complexes were purified from rabbit thymus extract by affinity chromatography using anti-PCNA monoclonal antibodies (TOB7, TO17, and TO30); monomeric and trimeric PCNA forms (AK-PCNA) were purified using anti-PCNA serum AK. The reactions to these antigens of 10 anti-PCNA-positive and 40 anti-PCNA-negative sera selected from 560 lupus patients were tested by immunoblotting, immunoprecipitation, and enzyme-linked immunosorbent assays (ELISAs). With one exception (serum OK), anti-PCNA-positive sera reacted exclusively with only the 34-kd polypeptide. In contrast, 14 of 40 anti-PCNA-negative sera reacted with multiple proteins within PCNA complexes. Most anti-PCNA-positive sera probably recognize as epitopes the binding sites for other proteins on PCNA, which are likely hidden when PCNA is complexed with other proteins. As a consequence, only serum OK reacted with the PCNA complex in a series of ELISAs. Using AK-PCNA as a competitive inhibitor, it was determined that serum OK reacts with both the 58-kd polypeptide and the 34-kd PCNA within complexes. Together with the results of a longitudinal analysis, these results suggest that the immune system of patient OK likely recognized the complexed PCNA protein, after which the autoimmune response spread to other elements of the complexes. Intermolecular-intrastructural help, leading to the spread of autoimmune response from PCNA to other proteins associated with its biologic function, plays a crucial role in the induction of the autoimmune response seen in lupus patients.

Reactivity of anti-proliferating cell nuclear antigen (PCNA) murine monoclonal antibodies and human autoantibodies to the PCNA multiprotein complexes involved in cell proliferation.

Proliferating cell nuclear Ag (PCNA) occurs as a component of multiprotein complexes during cell proliferation. We found the complexes to react with murine anti-PCNA mAbs, but not with anti-PCNA Abs in lupus sera. The complexes were purified from rabbit thymus extract by affinity chromatography using anti-PCNA mAbs (TOB7, TO17, and TO30) and analyzed by ELISA, immunoprecipitation, immunoblotting, and HPLC gel filtration. That PCNA was complexed with other proteins was demonstrated by its copurification with a group of proteins excluded by an HPLC G3000 SW column. Although immunoblot analysis showed the mAbs to react exclusively with the 34-kDa PCNA polypeptide, they nonetheless immunoprecipitated the same group of proteins, confirming the interaction of the isolated PCNA with other proteins. Anti-PCNA sera, including AK, which reacts with biologically functional sites on PCNA, did not react with complexed PCNA, but did react with it once it was dissociated from the complexes. PCNA complexes in turn reacted with murine anti-DNA mAbs, as well as with Abs against p21, replication protein A, DNA helicase II, cyclin-dependent kinases 4 and 5, and topoisomerase I. These findings suggest that the PCNA complexes purified using anti-PCNA mAbs comprise the "protein machinery" for DNA replication and cell cycle regulation. They also suggest that anti-PCNA mAbs are useful tools with which to characterize the protein-protein interactions within PCNA complexes, as well as the autoimmune responses to proteins interacting with PCNA, which may shed light on the mechanisms of autoantibody production in lupus patients.

Diverse antibody recognition patterns of the multiple Sm-D antigen polypeptides.

Anti-Sm antibodies are intrinsically associated with systemic lupus erythematosus. The major targets are the so-called B and D polypeptides. The number of Sm targets increased upon the report that SDS-PAGE conditions could be manipulated to display not one, but three Sm-D polypeptides. To characterize the relative reactivities of Sm-D1, Sm-D2, and Sm-D3, both human and murine autoantibodies were screened. These sera displayed two distinct patterns of reactivity. The Sm-D1/D3 pattern was at least four times more common than Sm-D1/D2/D3 recognition. The predominant immunoreactive protein was Sm-D1. We screened over 40 monoclonal antibodies that were derived from MRL mice and were selected as anti-Sm positive. Of these, 27 reacted with at least one Sm-D polypeptide by protein blot, but in contrast to the MRL sera, none of these antibodies reacted with Sm-D2. Rather, there were two recognition patterns of approximately equal abundance, against Sm-D1/D3 or Sm-D1 alone. Last, we explored the immune response to isolated Sm-D (containing all three D antigens) from rabbit thymus. The autoantibody produced reacted only with Sm-D2. There is accumulating evidence that the anti-Sm response is at least partially antigen-driven. The details of the intragroup relationships within the Sm-D family of proteins provide further insight into the Sm autoimmune response.

Screening of SLE Sera Using Purified Recombinant Sm-D1 Protein from a Baculovirus Expression System

The Sm-D1 polypeptide is a major target of autoantibodies diagnostic for systemic lupus erythematosus (SLE). The cDNA encoding the human antigen was expressed as a full-length, nonfusion protein using a eukaryotic baculovirus expression system. This recombinant version of Sm-D1 (rSm-D1) was purified to apparent homogeneity by a combination of differential extraction steps and FPLC chromatography. A direct antibody-binding ELISA was developed using the purified antigen. There was 96% correlation between the rSm-D1 and bona fide Sm-D1 from either HeLa cells or rabbit thymus when tested against Sm-positive patient sera by ELISA. The baculovirus-expressed Sm-D1 is reactive not only with patient anti-Sm sera, but also with anti-Sm monoclonal antibodies. Our results suggest that this rSm-D1 mimics the bona fide sources, providing a valuable addition to the roster of antigens available for SLE screening, epitope mapping and overall structure study.

Autoantibodies recognizing proteins copurified with PCNA in patients with connective tissue diseases.

Proliferating cell nuclear antigen (PCNA), one of the target antigen recognized by lupus sera, has been reported to be present as a subnuclear multi-peptide complex. But autoantibodies reacting with components of PCNA complex are poorly understood. To study the specificity of those autoantibodies, immunoreactivities of autoimmune sera against purified PCNA antigen were studied. PCNA antigens were purified from rabbit thymus extract by affinity column using murine monoclonal antibodies (mAbs) to PCNA, TOB7, TO17 and TO30. Immunoreactivities of autoimmune sera against purified PCNA were analyzed by WB. PCNA antigen purified by serum AK predominantly showed a 34 kD band specific for PCNA in SDS-PAGE. When antigens were purified by anti-PCNA mAb TOB7 and TO30 which are known to be targeting different epitopes on PCNA antigen, SDS-PAGE analysis showed various mol. wt of proteins in addition to the 34 kD PCNA while both AK and mAbs reacted only with 34 kD PCNA in WB. In WB using PCNA purified by TOB7, various immunoreactivities were observed at 150, 66, 58, 48, 45, 37, 32 and 16 kDa in sera from patients with connective tissue diseases. These results suggested that many of the proteins copurified with PCNA were also targets of autoimmune responses and these autoantibody expression may be induced through antigen-driven mechanisms.

Prevalence and clinical significance of antibodies to ribonucleoproteins in systemic lupus erythematosus in Malaysia.

One hundred and seventy patients with systemic lupus erythematosus (SLE) were studied for the prevalence of antibodies to the small RNA-associated proteins Ro/SSA, La/SSB, Sm, U1RNP and Sm. The relationship of these autoantibodies to different races, sexes and clinical manifestations of SLE was evaluated. Passive immunodiffusion was employed using human spleen extract as antigen source for Ro and rabbit thymus extract for La, Sm and U1RNP. We found the prevalence of antibodies to be as follows: anti-Ro/SSA, 36%; anti-La/SSB, 8%; anti-Sm, 15% ; anti-U1RNP, 21%. Except for a low prevalence of anti-La, the prevalence of these antibodies was similar to that in Western studies, The prevalence of anti-Ro/SSA is similar to that reported in the Western studies, but lower than that reported in the Oriental patients from Singapore and Hong Kong. Linkages of anti-Ro with anti-La antibodies were usual; however, although anti-Sm antibodies were usually associated with anti-U1RNP, they were more frequently associated with anti-Ro antibodies. The Malay patients had a high prevalence of anti U1RNP compared to other races. No gender difference was detected. Anti-Sm antibody was associated with serositis and anti-U1RNP antibodies with Raynaud's phenomenon. No association was found between the presence of skin renal or cerebral manifestations and any specific antibodies or combination of antibodies.

Detection of human-specific anti-La(SSB) antibodies in patients with rheumatoid arthritis

Sera from anti-Ro(SSA) positive and negative patients with rheumatoid arthritis (RA) were compared with those from patients with primary Sjogren's syndrome (pSS) and systemic lupus erythematosus (SLE) with regard to anti-La(SSB) antibodies. Several assays for anti-La(SSB) (RNA precipitation, counterimmunoelectrophoresis, and immunoblotting) demonstrated the presence of such antibodies in selected anti-Ro(SSA) positive (10/19 in RA and 18/37 in pSS and SLE) but not in anti-Ro(SSA) negative sera. In agreement with previous reports, anti-La(SSB) antibodies from pSS and SLE patients uniformly reacted with various cellular extracts used as sources of La(SSB) antigen, including extracts from human cultured cells (HeLa), calf thymus and rabbit thymus. In contrast, while all 10 anti-La(SSB) sera from RA patients reacted with the human HeLa cell extracts, only three of them also reacted with calf and rabbit thymus extracts. These results were further supported by the analysis of a cohort of 70 consecutively selected sera (displaying monospecific anti-Ro(SSA) reactivity against calf thymus extract) from patients with various rheumatic disorders, where human-specific anti-La(SSB) were detected in two out of the five of RA patients studied.

Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648.

The mechanism of antimicrobial activity of KRM-1648 (KRM), a new rifamycin derivative with potent antimycobacterial activity, was studied. Both KRM and rifampin (RMP) inhibited RNA polymerases from Escherichia coli and Mycobacterium avium at low concentrations: the 50% inhibitory concentrations (IC50s) of KRM and RMP for E. coli RNA polymerase were 0.13 and 0.10 micrograms/ml, respectively, while the IC50s for M. avium RNA polymerase were 0.20 and 0.07 microgram/ml. Both KRM and RMP exerted weak inhibitory activity against Mycobacterium fortuitum RNA polymerase, rabbit thymus RNA polymerases, E. coli DNA polymerase I, and two types of reverse transcriptases. Uptake of 14C-KRM by M. avium reached 18,000 dpm/mg (dry weight) 1.5 h after incubation, while uptake by E. coli cells was slight. KRM was much more effective in inhibiting uptake of 14C-uracil than was RMP (IC50 of KRM, 0.04 microgram/ml; IC50 of RMP, 0.12 microgram/ml). These findings suggest, first, that the potent antimycobacterial activity of KRM is due to inhibition of bacterial RNA polymerase and, second, that the activity of KRM against target organisms depends on target cell wall permeability.

Evaluation of recombinant ro/ssa, la/ssb, sm, and u1 rnp autoantigens in clinical diagnosis

This study comprises an analysis of the diagnostic usefulness of Ro/SSA, La/SSB, Sm and U1 RNP autoantigens obtained by DNA recombinant technology. We studied the presence of these autoantibodies in 33 patients with systemic lupus erythematosus (SLE) and 30 normal individuals by enzyme-linked immunosorbent assay (ELISA) using recombinant autoantigens and by Western immunoblot with these same antigens obtained from natural sources (rabbit thymus and human spleen). The strength of agreement between results found with these two techniques was moderate in the case of anti-Ro/SSA (kappa = 0.474, P < 0.001) and anti-U1 RNP (kappa = 0.566. P < 0.001) antibodies and almost perfect in the case of anti-La/SSB (kappa = 0871, P < 0.001) and anti-Sm (kappa = 0.833, P < 0.001). Furthermore, analysis of the disagreement between the two techniques evidenced a measurement bias for anti-Ro/SSA and anti-U1 RNP antibodies (Mc NEMAR'S statistic 13 and 11, respectively) whose direction, though difficult to define in the absence of a gold standard for such determinations, could be accounted for by the ELISA technique's greater tendency to produce positive results. Our conclusion is that the diagnostic usefulness of recombinant La/SSB and Sm autoantigens has been satisfactorily proven, whereas the case of the Ro/SSA and U1 RNP systems should be subject to further in-depth study of the autoepitopes recognised and the possible modifications which the latter might undergo as a result of their obtension from procariotic sources.

Application of cellular ELISA (CELISA) to the detection of human monoclonal autoantibodies

This work describes the application of cellular enzyme-linked immunosorbent assay (CELISA) for the detection of both polyreactive and monospecific human monoclonal antibodies against autoantigens. The CELISA is ideally suited for the screening of a large number of hybridoma culture supernatants, being, in this way, superior to other methods commonly used for the detection of autoantibody activity, such as indirect immunofluorescence on tissue sections and slide cell preparations, in terms of speed and sensitivity. This assay demonstrated higher sensitivity than ELISA using autoantigenic extracts from rabbit thymus, human spleen, nucleoprotamine, and salmon sperm nuclei, and enzyme immunoassays using ssDNA, dsDNA, and affinity purified autoantigens as substrate. The CELISA has been also successfully applied to the detection of autolymphocytotoxic antibody activity in heterohybridoma supernatants.

Selection of rabbit CD4- CD8- T cell receptor-gamma/delta cells by in vitro transformation with human T lymphotropic virus-I.

In vitro transformation of rabbit peripheral blood mononuclear cells (PBMC) with human T lymphotropic virus-I (HTLV)-infected human or rabbit cells resulted in CD4- CD8- cell lines, some of which caused acute leukemia when injected into rabbits. Structural analyses of the proviruses from cell lines with diverse pathogenic effects provided no clear correlation with lethality. The rabbit lines were provisionally designated T cells because they express interleukin 2R (IL-2R) and CD5 and lack surface immunoglobulin, but none express functional T cell receptor (TCR) alpha or beta transcripts. A more detailed characterization of the HTLV-I-infected cells was required to determine cell lineage and its potential influence on pathogenic consequences. Probes for rabbit TCR gamma and delta genes were derived and used to detect gamma and delta TCR RNA transcripts, identifying the in vitro transformed lines as gamma/delta T cells. CD4+ and CD8+ lines were derived from PBMC of HTLV-I-infected rabbits and CD4+ TCR-alpha/beta HTLV-I lines were derived from rabbit thymus, eliminating the possibility that the HTLV-I isolates used here transform only CD4- CD8- TCR-gamma/delta cells. The percentage of gamma/delta cells in rabbit PBMC is relatively high (23% in adult rabbits); this with diminution of CD4+ and CD8+ cells in IL-2-supplemented PBMC or thymocyte cultures may account for selection of rabbit HTLV-I-infected gamma/delta T cell lines in vitro. The availability of well-characterized T cell lines with diverse in vivo effects in the rabbit HTLV-I disease model allows evaluation of roles played by cell type in HTLV-I-mediated disease.

Glycosphingolipids of Rabbit, Sheep, and Pig Thymus

The thymus plays a major role in the immune system and many of the processes that occur in this tissue depend on cell-cell interactions. Glycoconjugates are known to mediate cell-cell interactions and thus to understand more fully the function of this class of compounds in thymus, structural characterization and quantification of the glycosphingolipids in thymus from sheep, rabbit, and pig were performed. Qualitative and quantitative differences were found for each species. Thymus from all three species contained neolacto (Galβ1-4GlcNAc) glycosphingolipids; however, significant differences in the types and quantities expressed by each animal were found. An evaluation of other classes of glycosphingolipids and their quantities demonstrate that pig thymus has a much different pattern of glycosphingolipid expression than sheep and rabbit thymus. The major glycosphingolipids in pig thymus are globo-series neutral glycosphingolipids (Gb 3 and Gb 4) and lactosyl-series gangliosides (GM 3 and GD 3). In contrast, sheep and rabbit thymus express significant levels of lacto and neolacto neutral glycosphingolipids, and also lacto and neolacto gangliosides, including three previously unidentified compounds. The major difference in glycosphingolipid expression in these two species was the presence of branched-chain gangliosides in sheep thymus.