Tools to study memory B cell (MBC) development and function are needed to understand their role in supporting sustained protection against recurrent infections. While human MBCs are traditionally measured using blood, there is a growing interest in elucidating their behavior within lymphoid tissues, which are the main sites where adaptive immune responses are orchestrated. In this chapter, we introduce a high-throughput organoid system that is derived from primary human lymphoid tissues. The approach can recapitulate many hallmarks of successful adaptive immune responses and capture inter-individual variation in response to a variety of stimuli. Lymphoid tissue organoids enable characterization of pre-existing antigen-specific MBCs within an entirely human system and can provide valuable insights into MBC dynamics.

OBJECTIVE: Tonsillectomy is an effective treatment for periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome. Tonsillotomy has a milder operative risk profile and postoperative morbidity in children than tonsillectomy. We aimed to compare the efficacy of tonsillotomy to observation-only in children with PFAPA syndrome at a 3-month follow-up.
METHODS: This was a randomized multicenter trial with sequential design. Participants were randomized into a tonsillotomy group and a control group that was only observed. The trial started in 1/2017 and was accomplished in 12/2021 with 16 patients (10 boys, six girls, the mean age 4.2 years). The symptoms were monitored with daily symptom diaries.
RESULTS: After the 3-month follow-up, 7/8 patients (87.5%) in the tonsillotomy group and 2/8 (25%) patients in the control group were free from PFAPA symptoms (95% CI 13% to 87%; p = 0.0021). The mean number of days with fever was 2.6 (SD 3.7) in the tonsillotomy group and 8.0 (SD 6.5) days in the control group (n = 8) (p = 0.06). Mean number of fever days compatible with PFAPA syndrome was 0.8 (SD 1.4) in the tonsillotomy group and 6.5 (SD 6.0) in the control group (95%CI -10% to -1%; p = 0.007). Rescue tonsillectomy was needed for all patients in the control group and none of the patients in the tonsillotomy group.
CONCLUSIONS: Tonsillotomy might be an effective treatment option for children with PFAPA syndrome. Further studies are needed to clarify the long-term efficacy of tonsillotomy for treating PFAPA.
METHODS: 2 Laryngoscope, 134:968-972, 2024.

BACKGROUND: Persistent inflammation and immune activation are associated with lymph node fibrosis and end-organ diseases in treatment-suppressed people living with HIV (PLWH). We investigated the effect of switching to raltegravir and/or adding losartan on lymphoid tissue fibrosis and on the inflammatory/immune-activation mediators in treated HIV patients.
METHODS: Chronic HIV-infected patients treated with two nucleoside reverse transcriptase inhibitors (2NRTI) and one non-NRTI (NNRTI) or protease inhibitor (PI) during at least 48 weeks were randomized to four groups (n = 48): 2NRTI + efavirenz (EFV), 2NRTI + EFV + losartan, 2NRTI + raltegravir and 2NRTI + raltegravir + losartan for 48 weeks. Tonsillar biopsy and peripheral blood markers of CD4 and CD8 T-lymphocyte activation and senescence, monocyte activation and soluble markers of inflammation were determined at baseline and at week 48 and compared between groups.
RESULTS: No changes in lymphoid tissue architecture were observed. Adding losartan had no impact on lymphocyte subsets. Conversely, patients who switched to raltegravir showed a higher decrease in all activated [CD4+CD38+HLA-DR+, -0.3 vs. 0.48 (P = 0.033); CD8+CD38+ HLA-DR+, -1.6 vs. 1.3 (P = 0.02)] and senescent [CD4+CD28-CD57+, -0.3 vs. 0.26 (P = 0.04); CD8+CD28-CD57+, -6.1 vs. 3.8 (P = 0.002)] T lymphocytes. In addition, the median CD4/CD8 ratio increased by 0.35 in patients in the raltegravir group vs. 0.03 in the other arms (P = 0.002). Differences between groups in monocyte subpopulations or soluble inflammation markers were not observed.
CONCLUSIONS: Losartan had no effect on lymphoid fibrosis or immune activation/inflammation. Conversely, switching to a regimen with raltegravir significantly decreased activated and senescent T-lymphocyte subpopulations and increased CD4/CD8 ratio in successfully treated PLWH.

OBJECTIVE: To evaluate the existence of tertiary lymphoid structures(TLS) in oral lichenoid lesions and its compositional characteristics of immune cells.
METHODS: Tissue samples of normal oral mucosa, oral lichen planus (OLP) and oral lichenoid tissue reaction(OLTR) were collected, thirty cases in each group. Hematoxylin-eosin(H-E) staining was performed to identify the TLS-like structures, and immunohistochemistry (IHC) staining was applied to assess the structure and amount of infiltrating CD3+ T cells, CD19+, CD20+ B cells, CD21+ follicular dendritic cells (FDC), Bcl-6+ germinal centers, CD34+ PNAd+ venules and CD34+ Gp36+ micro lymphatic vessels in TLS of OLL. Histopathology and molecular markers were used to evaluate the morphological performance of TLS in OLL. Chi-square test (Fisher exact probability method) was applied to compare the proportion of TLS in each group; integral optical density (IOD) method was used to calculate the expression level of each molecular marker, nonparametric t test (Mann-Whitney U test) was employed to analyze their difference. Statistical analysis was performed with GraphPad Prism 7.0 software.
RESULTS: In OLP group and OLTR group, 46.7% (14/30) and 23.4% (7/30) cases had TLS-like structures, respectively. The frequency of TLS-like structures was not correlated with the type of disease(P>0.05). Compared with the control group, the molecular markers in OLP group and OLTR group were highly expressed, and the expression of CD19, CD20, and CD21 in OLP group had morphological and structural characteristics of TLS. The expression of Bcl-6(mean and standard deviation of IOD were 15 498±15 108 vs. 1 841±2 276, P<0.0001), CD20 (13 067±9 049 vs. 7 695±5 159, P<0.05), CD21 (13 968±14 560 vs. 2 552±2 584, P<0.0001), PNAd (10 328±10 383 vs. 1 756±1 570, P<0.0001) and Gp36 (12 778±12 390 vs. 2 313±2 578, P<0.0001) showed significant differences between OLP and OLTR tissues, but it could not be used as the criteria for identifying the type of diseases without morphological characters.
CONCLUSIONS: TLS exists in OLL lesions, mainly presented as non-classical forms. The classical forms can be occasionally found. CD20 and CD21 can be used as the biomarkers to identify the TLS in OLL. TLS can not be used as the diagnosing criteria for identifying OLP or OLTR.

BACKGROUND: Large granular lymphocyte (LGL) leukaemia is considered a mature T-cell or natural killer (NK) cell neoplasm, characterised by a clonal proliferation of LGL.
OBJECTIVE: To analyse the characteristics and to establish (if possible) the prognostic parameters of these patients diagnosed in a single centre: University Hospital of Donostia.
METHODS: We retrospectively studied data about 308 patients with LGL leukaemia diagnosed in our centre.
RESULTS: The frequency of T-LGL leukaemia and chronic lymphoproliferative disorder of NK cells was 89% and 6.8% respectively, and no aggressive NK-LGL leukaemia was seen in our population. The median age at diagnosis was 65.7 years and male-to-female ratio was 1.08. 59% of our patients were asymptomatic at the time of diagnosis. Most patients presented lymphocytosis and 63.6% more than 20% LGLs in the peripheral blood count, but it has to be taken into account that these results may be influenced by the selection bias of our study, as we recognised these patients as \'alarms of the laboratory analysers\'. Neutropenia was the most common cytopenia, and autoimmune disorders were described in 16.5% of the patients. Only 12 patients (3.9%) required treatment, a much lower percentage that the one reported in the literature, and this is consistent with the fact that patients were less symptomatic than in other series, as we expected. The 5-year and 15-year overall survival was 92% and 87%, respectively.
CONCLUSIONS: Our patients may represent the even more benign end of the spectrum of clonal T LGL and NK proliferations.

Cartilaginous fish are located at a pivotal point in phylogeny where the adaptive immune system begins to resemble that of other, more-derived jawed vertebrates, including mammals. For this reason, sharks and other cartilaginous fish are ideal models for studying the natural history of immunity. Insights from such studies may include distinguishing the (evolutionarily conserved) fundamental aspects of adaptive immunity from the (more recent) accessory. Some lymphoid tissues of sharks, including the thymus and spleen, resemble those of mammals in both appearance and function. The cartilaginous skeleton of sharks has no bone marrow, which is also absent in bony fish despite calcified bone, but cartilaginous fish have other Leydig\'s and epigonal organs that function to provide hematopoiesis analogous to mammalian bone marrow. Conserved across all vertebrate phylogeny in some form is gut-associated lymphoid tissues, or GALT, which is seen from agnathans to mammals. Though it takes many forms, from typhlosole in lamprey to Peyer\'s patches in mammals, the GALT serves as a site of antigen concentration and exposure to lymphocytes in the digestive tract. Though more complex lymphoid organs are not present in agnathans, they have several primitive tissues, such as the thymoid and supraneural body, that appear to serve their variable lymphocyte receptor-based adaptive immune system. There are several similarities between the adaptive immune structures in cartilaginous and bony fish, such as the thymus and spleen, but there are mechanisms employed in bony fish that in some instances bridge their adaptive immune systems to that of tetrapods. This review summarizes what we know of lymphoid tissues in cartilaginous fishes and uses these data to compare primary and secondary tissues in jawless, cartilaginous, and bony fishes to contextualize the early natural history of vertebrate mucosal immune tissues.

Studying isolated cells from mucosa-associated lymphoid tissues (MALT) allows understanding of immune cells response in pathologies involving mucosal immunity, because they can model host-pathogen interactions in the tissue. While isolated cells derived from tissues were the first cell culture model, their use has been neglected because tissue can be hard to obtain. In the present protocol, we explain how to easily process and culture tonsillar mononuclear cells (TMCs) from healthy human tonsils to study innate immune responses upon activation, mimicking viral infection in mucosal tissues. Isolation of TMCs from the tonsils is quick, because the tonsils barely have any epithelium and yield up to billions of all major immune cell types. This method allows detection of cytokine production using several techniques, including immunoassays, qPCR, microscopy, flow cytometry, etc., similar to the use of peripheral mononuclear cells (PBMCs) from blood. Furthermore, TMCs show a higher sensitivity to drug testing than PBMCs, which needs to be considered for future toxicity assays. Thus, ex vivo TMCs cultures are an easy and accessible mucosal model.

Chronic wasting disease is a fatal, horizontally transmissible prion disease of cervid species that has been reported in free-ranging and farmed animals in North America, Scandinavia, and Korea. Like other prion diseases, CWD susceptibility is partly dependent on the sequence of the prion protein encoded by the host\'s PRNP gene; it is unknown if variations in PRNP have any meaningful effects on other aspects of health. Conventional diagnosis of CWD relies on ELISA or IHC testing of samples collected post-mortem, with recent efforts focused on antemortem testing approaches. We report on the conclusions of a study evaluating the role of antemortem testing of rectal biopsies collected from over 570 elk in a privately managed herd, and the results of both an amplification assay (RT-QuIC) and conventional IHC among animals with a several PRNP genotypes. Links between PRNP genotype and potential markers of evolutionary fitness, including pregnancy rates, body condition, and annual return rates were also examined. We found that the RT-QuIC assay identified significantly more CWD positive animals than conventional IHC across the course of the study, and was less affected by factors known to influence IHC sensitivity - including follicle count and PRNP genotype. We also found that several evolutionary markers of fitness were not adversely correlated with specific PRNP genotypes. While the financial burden of the disease in this herd was ultimately unsustainable for the herd owners, our scientific findings and the hurdles encountered will assist future CWD management strategies in both wild and farmed elk and deer.

A cross sectional descriptive study was performed on 40 postmortem vermiform appendix (male 24 and female 16) to find out the diameter of lymphoid follicle of vermiform appendix of Bangladeshi people. The specimens were collected from autopsy laboratory of the Department of Forensic Medicine, Mymensingh Medical College, Mymensingh, Bangladesh by purposive sampling technique and were divided into four age groups. They were Group A (upto 20 years), Group B (21 to 40 years), Group C (41 to 60 years) and Group D (above 60 years). For this purpose, about 3mm long of whole thickness transverse section was taken from the middle of the vermiform appendix and thus the permanent slides were made for microscopic examination. To measure the diameter of the lymphoid follicle two measurements were taken. One was taken at the maximum diameter and another was perpendicular to it by ocular micrometer. Diameter of one largest and one smallest lymphoid follicles were measured and find out the mean diameter of lymphoid follicle between them. Diameter of lymphoid follicle = (Maximum transverse diameter + perpendicular diameter) /2. All data were recorded in the predesigned data sheet, analyzed by SPSS program (version 21, 2012) and compared with the findings of other national and international studies and standard text books. It was observed that diameter of lymphoid follicle of vermiform appendix gradually decreased as age advanced. The mean±SD diameter of lymphoid follicle was 580.31±37.07, 545.58±38.37, 485.68±40.20 and 428.12±68.41μm in Group A, B, C and D respectively. Statistical analysis shows that the mean differences of diameter of lymphoid follicle between A&B, C&D were statistically non significant at p= or >0.05 level, difference between Group B&C was statistically moderately significant at p<0.01 level and differences between Group A&C, B&D, A&D were statistically highly significant at p<0.001 level. Mean diameter of lymphoid follicle of vermiform appendix in male was higher (584.30±12.65μm in Group A, 549.42±38.36μm in Group B, 487.38±39.91μm in Group C, 430.68±70.30μm in Group D) than in female (576.31±53.77μm in Group A, 536.61±45.14μm in Group B, 483.14±46.68μm in Group C, 424.28±75.95μm in Group D) but mean difference between sexes in the different groups was statistically non significant at p=or >0.05 level. The present study will help to increase the information pool on the diameter of lymphoid follicle of vermiform appendix of Bangladeshi people.

BACKGROUND: Analyze the clinical, demographic, histopathological, and immunohistochemical features of oral lymphoepithelial cyst (OLEC).
METHODS: Samples were retrospectively retrieved from five oral pathology services. Clinical and demographic data were collected from patient charts. Histopathological and immunohistochemical (CD3 and CD20) features were evaluated. Data analysis involved descriptive statistics and bivariate analyses (P ≤ .05).
RESULTS: Seventy-seven cases were found among a total of 146 150 specimens (0.05%). OLEC was predominantly diagnosed in females (70.1%). Mean patient age was 46.51 years. The lesions arose mainly on the lateral border of the tongue (40.3%), measured up to 1 cm (61.0%), and were asymptomatic (64.9%). Twenty-four lesions (31.2%) were white. Forty-one cases (53.2%) presented lymphocytic inflammatory infiltrate with no specific arrangement. The cystic lining was composed of a non-keratinized stratified epithelium (59.7%) presenting hyperplasia (39.0%). Connection with the surface, epithelium was found in 23 cases (29.9%) and 31 (40.3%) cases had two or more cystic cavities. The lumen content was predominantly desquamated cells (48.1%). Subgemmal neurogenous plaque was found in 11/42 (26.2%) cases involving the tongue. CD20+ cells predominated in 36/63 cases (57.2%), and lymphocytic inflammatory infiltrate was not always continuous around the cystic cavity (52.4%).
CONCLUSIONS: Lymphoepithelial cyst is an uncommon lesion of the oral cavity. The present study offers the largest sample of OLEC for which clinical, demographic, histopathological, and immunohistochemical features were evaluated. The clinical and demographic findings were similar to those described in previous reports, but the microscopic analyses revealed interesting aspects of the cystic epithelium and the lymphocytic inflammatory infiltrate in OLEC.