UNASSIGNED: Cyclophosphamide (CP) is one of the most effective immunosuppressive agents. To understand the mechanisms used by the CP and MSCs in the kidney, we investigated their effects on some pathways.
UNASSIGNED: 4 groups of female rats were used. GI: was the normal control group treated with saline solution. Groups G II, G III, and G IV were treated with CP. G I and G II groups were sacrificed on the fourth day after treatment., G III (Auto healing group) was left without treatment after the CP injection for six days. The G IV group was treated with MSCs on the fourth day after the CP injection. G III and G IV groups were sacrificed six days after treatment, and the kidney was removed and processed.
UNASSIGNED: CP induced up-regulation in CD14 and CD21 positive cells and caspase. Significant down-regulation of previous markers in groups III and IV. CP exerted a downregulation effect on AKT/ PI3K, that were ameliorated in groups III and IV. A significant increase in P53, BCL2, as well as VEGF in Group IV (P < 0 05).
UNASSIGNED: MSCs play a vital function in the immune inhibition in CP-treated rats through PI3K/AKT pathway.

The current investigation aims to study the embryonic dermis formed in the early stages of development and identify the initial interstitial components of the dermis that serve as biological and structural scaffolds for the development of the dermal tissue. To investigate the dermal structure, the current study used morphological and immunological techniques. TCs identified by TEM. They had a cell body and unique podomeres and podoms. They formed a 3D network spread throughout the dermis. Homocellular contact established between them, as well as heterocellular contacts with other cells. Immunohistochemical techniques using specific markers for TCss CD34, CD117, and VEGF confirmed TC identification. TCs represent the major interstitial component in the dermal tissue. They established a 3D network, enclosing other cells and structures. Expression of VEGF by TC promotes angiogenesis. TCs establish cellular contact with sprouting endothelial cells. At the site of cell junction with TCs, cytoskeletal filaments identified and observed to form the pseudopodium core that projects from endothelial cells. TCs had proteolytic properties that expressed MMP-9, CD68, and CD21. Proteolytic activity aids in the removal of components of the extracellular matrix and the phagocytosis of degraded remnants to create spaces to facilitate the development of new dermal structures. In conclusion, TCs organized the scaffold for the development of future dermal structures, including fibrous components and skin appendages. Studying dermal TCs would be interested in the possibility of developing therapeutic strategies for treating different skin disorders and diseases.

The clinical presentation of CD21 deficiency in 2 siblings caused by a novel mutation in the CD21 gene is reported, and the frequency of this mutation in the Danish population is explored. Successful treatment with IgG replacement in both patients with CD21 deficiency is also reported.

Reviewing old protocols, it was found that Raji, a CR2-posistive cell line, binds both endogenous (e-C3) and exogenous C3 (i-C3). The processing of i-C3 to an i-C3b-like protein and their fixation to CR2 isoforms resulted in the formation of heterodimers whose units might be linked via thioester by low m.w. molecule(s). In an attempt to study the origin of the low m.w. molecules, it was found that they were detected following I12⁵-C3d treatment with NHS or hi-S. Indirect evidence would suggest that the products of C3 fragment fixation could have a short half-life and that the aromatic residues present in C3d might have different physico-chemical characteristics than those present in C3c. The surface hydrophobicity expressed by these aromatic residues could be required for the fixation of C3 or CR2 fragments to cell surface proteins.

BACKGROUND: Studies suggested that the immunophenotype of hyaline vascular type Castleman disease (HVCD) lacked characteristics, which was easy to be confused with other diseases.
METHODS: From January 2010 to June 2022, 17 cases of HVCD were selected from the Department of Pathology of Shaanxi Provincial People\'s Hospital and the Department of Pathology of Shaanxi Provincial Cancer Hospital. 13 cases of reactive hyperplastic lymph nodes (RHL) and 11 cases of follicular lymphoma (FL) were selected as the control group. All cases were performed CD3, CD20, CD21 and BCL2 immunohistochemical staining.
RESULTS: (i) In 17 cases of HVCD, the negative area of BCL2 of germinal center was significantly smaller than the negative area of CD3 of germinal center. However, in 13 cases of RHL, the negative area of CD3 of germinal center was basically consistent with the negative area of germinal center of BCL2 of germinal center. In 11 cases of FL, in neoplastic follicles, the negative area of CD3 was basically consistent with the positive area of BCL2. The difference between HVCD group and other two groups of diseases was statistically significant (P < 0.05). (ii) In 17 cases of HVCD, the negative area of BCL2 of germinal center was significantly smaller than the follicular dendritic cell (FDC) meshworks expressed by CD21. However, in 13 cases of RHL, the FDC meshworks expressed by CD21 were basically consistent with the negative area of BCL2 of germinal center. In 11 cases of FL, in neoplastic follicles, the FDC meshworks expressed by CD21 was basically consistent with the positive area of BCL2. The difference between HVCD group and other two groups of disease was statistically significant (P < 0.05).
CONCLUSIONS: HVCD has unique immunophenotypic characteristics. The negative area of BCL2 of germinal center is significantly smaller than the negative area of CD3. The negative area of the BCL2 of germinal center is significantly smaller than the FDC meshworks expressed by CD21. These two immunophenotypic features in HVCD are very important in diagnosis and differential diagnosis.

To improve accuracy in evaluating stallion ejaculates, an antibody-based, flow cytometric assay for the detection and identification of leukocyte subpopulations (CD4-, CD8-, CD21-, CD172a-positive cells) in stallion semen (n = 12) was established. For establishment of the assay, native semen was supplemented with blood leukocytes (control: 20% leukocytes, 80% sperm cells) and analysed by flow cytometry. Adding antioxidants (ascorbic acid and butylated hydroxytoluol) to semen immediately after collection inhibited rapid death of lymphoid cells in sperm leukocyte mixtures. In control set-ups, 27.85 ± 5.7% of events were positive for CD4, CD8, CD21 or CD172a, while in native semen samples, leukocytes were scarce (0.114 ± 0.134%). The most abundant leukocyte subpopulation in semen was of lymphoid origin (CD4-positive cells [0.015 ± 0.02%]), whereas CD21-positive cells (B cells; 0.001 ± 0.001%) were virtually absent in ejaculates of fertile stallions. This presented flow cytometric assay for the detection and identification of different leukocyte population in equine antioxidant-treated ejaculates can be used as an additional tool for spermatological examination in stallions.

An in-depth knowledge of non-neoplastic patterns is fundamental to diagnose neoplasia. In the present study, we described the flow cytometric (FC) cell size (FSC) and fluorescence intensity (MFI) of B- and T-lymphocytes in 42 canine reactive lymph nodes and 36 lymphomas. Proliferative activity (Ki67%) in reactive lymph nodes was also reported. Reactive lymph nodes were composed of a mixed population of small and large T (CD5+) and B (CD21+) cells. Small T-cells were larger in size than small B-cells, and large T-cells were larger than large B-cells. Small T-cells were composed of CD5+CD21- and CD5+CD21+dim subpopulations. Large B-cells were <20% in reactive lymph nodes and >20% in lymphomas and showed a higher FSC in lymphomas than in reactive lymph nodes. Large T-cells were <4% in reactive lymph nodes and >4% in lymphomas and showed a higher CD5 MFI in lymphomas (if expressed) compared to reactive lymph nodes. A subset of CD5+CD21+dim lymphocytes was recognized in addition to CD5+CD21- and CD5-CD21+ cells. In T-zone lymphomas, neoplastic cells had higher FSC and CD21 MFI values than small CD5+CD21+dim cells in reactive lymph nodes. Ki67% values were higher than those reported in normal lymph nodes, and largely overlapped with those reported in low-grade lymphomas and partially in high-grade lymphomas. Our results may contribute to making a less operator-dependent FC differential between lymphoma and reactive lymph nodes.

Background. Follicular dendritic cell (FDC) sarcoma is a rare neoplasm arising from follicular dendritic cells (FDCs). It can be nodal or extranodal. Histological diagnosis of extranodal FDC sarcoma in the head and neck region is challenging and a significant percentage are misdiagnosed. Objectives. To report clinicopathological features of head and neck extranodal FDC sarcoma cases and discuss differential diagnoses. Methods. Seven head and neck extranodal FDC sarcomas were retrieved and clinicopathological features were noted. Results. Two tumors each involved parapharyngeal space and tonsil while remaining cases involved the parotid, soft tissue of neck and oropharynx. Age range was 12 to 79 years (mean and median age were 40 and 44 years respectively) and there was a male predilection (6 males: 1 female). All showed spindle to ovoid cells arranged in fascicles, whorls and/or storiform pattern. Mitoses ranged from 3 to 20/mm2. All tumors expressed CD21 and CD23. Two patients died of their disease at 9 and 16 months. Both had tumors larger than 5 cm with ≥10 mitoses/mm2. Three patients were alive at 12, 44 and 184 months. Conclusions. There was a distinct male predominance in our cohort. FDC sarcoma should be included in the differential diagnosis of spindle cell extranodal neoplasms in the head and neck with a whorled growth pattern and intratumoral lymphocytes. Head and neck region tumors show similar clinicopathologic characteristics as their counterparts at other locations with potential for aggressive behavior especially in tumors greater than 5 cm in size and with high mitotic rates.

Long-term protective immunity to infectious disease depends on cell-mediated and humoral immune responses. Induction of a strong humoral response relies on efficient B cell activation and differentiation to long-lived plasma cells and memory B cells. For many viral or bacterial infections, a single encounter is sufficient to induce such responses. In malaria, the induction of long-term immunity can take years of pathogen exposure to develop, if it occurs at all. This repeated pathogen exposure and suboptimal immune response coincide with the expansion of a subset of B cells, often termed atypical memory B cells. This subset is present at low levels in healthy individuals as well but it is observed to expand in an inflammatory context during acute and chronic infection, autoimmune diseases or certain immunodeficiencies. Therefore, it has been proposed that this subset is exhausted, dysfunctional, or potentially autoreactive, but its actual role has remained elusive. Recent reports have provided new information regarding both heterogeneity and expansion of these cells, in addition to indications on their potential role during normal immune responses to infection or vaccination. These new insights encourage us to rethink how and why they are generated and better understand their role in our complex immune system. In this review, we will focus on recent advances in our understanding of these enigmatic cells and highlight the remaining gaps that need to be filled.

Although chimeric antigen receptor-modified (CAR) T cell therapy has been successfully applied in the treatment of acute B lymphocytic leukemia, its effect on Burkitt lymphoma (BL) and chronic B lymphocytic leukemia (B-CLL) is unsatisfactory. Moreover, fatal side effects greatly impede CAR T cell application. Extracellular vesicles (EVs) are excellent carriers of therapeutic agents. Nevertheless, EVs mainly accumulate in the liver when administered without modification. As an envelope glycoprotein of Epstein-Barr viruses, gp350 can efficiently bind CD21 on B cells. Here, gp350 was directly anchored onto red blood cell EVs (RBC-EVs) via its transmembrane region combined with low-voltage electroporation. The results showed that gp350 could anchor to RBC-EVs with high efficiency and that the resulting gp350-anchored RBC-EVs (RBC-EVs/gp350Etp) exhibited increased targeting to CD21+ BL and B-CLL relative to RBC-EVs. After the loading of doxorubicin or fludarabine, RBC-EVs/gp350Etp had powerful cytotoxicity and therapeutic efficacy on CD21+ BL or B-CLL, respectively. Moreover, RBC-EVs/gp350Etp loaded with a drug did not exhibit any apparent systemic toxicity and specifically induced the apoptosis of tumor B cells but not normal B cells. Therefore, our findings indicate that drug-loaded RBC-EVs/gp350Etp may be adopted in the treatment of CD21+ B cell malignancies.