Plasma-like Cells Research Articles

Single-cell atlas of rainbow trout peripheral blood leukocytes and profiling of their early response to infectious pancreatic necrosis virus.

The recent development of single cell sequencing technologies has revolutionized the state-of-art of cell biology, allowing the simultaneous measurement of thousands of genes in single cells. This technology has been applied to study the transcriptome of single cells in homeostasis and also in response to pathogenic exposure, greatly increasing our knowledge of the immune response to infectious agents. Yet the number of these studies performed in aquacultured fish species is still very limited. Thus, in the current study, we have used the 10x Genomics single cell RNA sequencing technology to study the response of rainbow trout (Oncorhynchus mykiss) peripheral blood leukocytes (PBLs) to infectious pancreatic necrosis virus (IPNV), an important trout pathogen. The study allowed us to obtain a transcriptomic profile of 12 transcriptionally distinct leukocyte cell subpopulations that included four different subsets of B cells, T cells, monocytes, two populations of dendritic-like cells (DCs), hematopoietic progenitor cells, non-specific cytotoxic cells (NCC), neutrophils and thrombocytes. The transcriptional pattern of these leukocyte subpopulations was compared in PBL cultures that had been exposed in vitro to IPNV for 24h and mock-infected cultures. Our results revealed that monocytes and neutrophils showed the highest number of upregulated protein-coding genes in response to IPNV. Interestingly, IgM+IgD+ and IgT+ B cells also upregulated an important number of genes to the virus, but a much fainter response was observed in ccl4 + or plasma-like cells (irf4 + cells). A substantial number of protein-coding genes and genes coding for ribosomal proteins were also transcriptionally upregulated in response to IPNV in T cells and thrombocytes. Interestingly, although genes coding for ribosomal proteins were regulated in all affected PBL subpopulations, the number of such genes transcriptionally regulated was higher in IgM+IgD+ and IgT+ B cells. A further analysis dissected which of the regulated genes were common and which were specific to the different cell clusters, identifying eight genes that were transcriptionally upregulated in all the affected groups. The data provided constitutes a comprehensive transcriptional perspective of how the different leukocyte populations present in blood respond to an early viral encounter in fish.

Teleost fish IgM+ plasma-like cells possess IgM-secreting, phagocytic, and antigen-presenting capacities.

Plasma cells are terminally differentiated antibody-secreting B lymphocytes that contribute to humoral immunity by producing large numbers of antibodies. Increasing evidence suggests that teleost fish B cells share certain characteristics with mammalian B1 B cells, including antibody-secreting, phagocytic, and antigen-presenting capacities. However, the difference between mature B cells and plasma cells remains unclear. In this study, we found that, based on their light-scattering characteristics, tilapia anterior kidney (AK) leukocytes can be categorized into two IgM+ B-cell subsets: the lymphoid (L) gate and granulocyte–monocyte/macrophage (G-M) subsets. G-M gate cells are more numerous than L-gate cells and have higher mean fluorescence, but lower forward scatter and side scatter. We analyzed the morphological and ultrastructural features of sorted IgM+ cells and found that L-gate IgM+ cells have a high nucleus–cytoplasm ratio and lymphocyte-like morphology, whereas G-M gate IgM+ cells have a small nucleus, more abundant endoplasmic reticulum, and a larger number of mitochondria, and have a plasma cell-like or macrophage-like morphology. To further characterize the cell types, we examined the specific patterns of expression of B-cell- and T-cell-related genes. We found that B-cell-specific genes were expressed by both L-gate and G-M gate IgM+ cells, and that G-M gate IgM+ cells secreted extremely high levels of IgM. However, T-cell-related genes were highly expressed only in L-gate IgM– cells. These results suggest that G-M gate IgM+ cells are similar to plasma-like cells, with high antibody-secreting capacity. Given that G-M gate cells include the granulocyte, monocyte, and macrophage cell types, but not B cells, monocyte/macrophage markers were used to investigate the cell types further. A macrophage receptor with a collagenous structure was frequently observed, and macrophage-expressed gene-1 was highly expressed, in the G-M gate IgM+ cells. Phagocytic capacity, as determined by ingestion of beads or bacteria, was significantly higher in G-M gate IgM+ cells than in L-gate IgM+ cells, as was antigen-processing capacity. Our findings show that tilapia AK leukocytes can be divided into two IgM+ B-cell subsets and that G-M gate IgM+ cells resemble plasma-like cells, having high antibody-secreting, phagocytic, and antigen-presenting capacities. Thus, this study increases our understanding of the functions of teleost fish plasma-like cells.

CD27 plays roles in T cell-dependent response and B cell differentiation in Nile tilapia (Oreochromis niloticus)

CD27 is a member of tumor necrosis factor receptor superfamily, and plays a central role in B cell-mediated immune response in mammals. However, the functional characterization of CD27 molecule remains unclear in bony fish. In this study, the CD27 molecule of Nile tilapia (OnCD27) was cloned and its functional characterization was identified by pursuing the expression patterns in T cell-dependent (TD) response and B cell differentiation process. The open reading frame (ORF) of OnCD27 is 666 bp of the nucleotide sequence, encoding a protein of 221 amino acid including two TNFR domains in the extracellular region. Bioinformatics analysis indicated that OnCD27 was highly homologous to other bony fish and similar to mammals. Tissue distribution analysis displayed that the relative expression of OnCD27 was highest in spleen among the examined tissues. The OnCD27 expression was significantly up-regulated in spleen and head kidney post-challenge of a TD antigen keyhole limpet hemocyanin (KLH) in vivo. Following recombination Oreochromis niloticus IL10 ((r)OnIL10) protein stimulation in vitro, the up-regulation of OnCD27 expression was detected during the process of B cell differentiation. Further, analysis of OnCD27 expression in different B cell subsets revealed that the OnCD27 expression in P50 plasma-like cells was remarkable higher than P60 plasmablast-like and P70 naïve mature B cells. Moreover, the OnCD27 transcripts presented a higher expression level in IgMlo plasma-like cells than IgMhi activated B cells. In summary, the collective results may provide that OnCD27 plays roles in T cell-dependent response and B cell differentiation in Nile tilapia.

Effects of Cell Differentiation on the Phagocytic Activities of IgM+ B Cells in a Teleost Fish.

Teleost B cells have phagocytic activities for ingesting particulate antigens, such as bacteria, in addition to the functional secretion of immunoglobulins (Igs). In the present study, the phagocytic activities of IgM+ B cells under various differentiational conditions residing in peripheral blood leukocytes were investigated in a teleost fish Nile tilapia (Oreochromis niloticus). The IgM+ B cells were recognized as IgMlo or IgMhi subsets based on their membrane IgM (mIgM) levels. The mIgM, secreted IgM (sIgM), major histocompatibility complex class II and reactive oxygen species were detected. Expressions of transcription factors (Pax5 and Blimp-1) and B cell signaling molecules (CD79a, CD79b, BLNK, and LYN) suggested that IgMlo B cells were resembling as plasma-like cells and IgMhi resembling as naïve/mature B cells, respectively. Analysis of phagocytic activities demonstrated that both IgMlo and IgMhi B cells have a similar phagocytic ability (phagocytosis percentage); however, the phagocytic capacity [phagocytic index and the mean fluorescence intensity (MFI)] of IgMhi B cells was significantly higher than that of IgMlo B cells. Taken together, the results indicated that B cell differentiation may cause the decrease of phagocytic capacity but not phagocytic ability of phagocytic IgM+ B cells in teleost. The finding may provide an evolutionary evidence for understanding the greater specialization of the B cell in more sophisticated adaptive humoral immunity, by decreasing phagocytic activity in order to contribute its function more specifically into antibody-secreting.

Identification and characterization of plasma-like cells in grass carp

Identification and characterization of plasma-like cells in grass carp

Bortezomib-resistant nuclear factor κB expression in stem-like cells in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a subtype of B-cell Non-Hodgkin's Lymphoma (NHL) and accounts for approximately 6% of all lymphomas. Unlike small lymphocytic lymphoma and chronic lymphocytic lymphoma, which are relatively sensitive to chemotherapy, MCL is highly refractory to most chemotherapy, and has the worst survival rate among NHL patients. Stem-like cells in MCL, which we have termed mantle cell lymphoma-initiating cells (MCL-ICs), enriched in the population that are lack of prototypic B-cell marker CD19. These cells were able to self-renew upon serial transplantation and are highly tumorigenic. Importantly, these stem-like cells confer chemotherapeutic resistance to MCL. In this report, we show that stem-like MCL-ICs are resistant to bortezomib, as well as chemotherapeutic regimens containing bortezomib, despite constitutive nuclear factor-κB (NF-κB) expression. Interestingly, bortezomib treatment induced MCL-IC differentiation in plasma-like cells with upregulated expression of CD38 and CD138. This process was accompanied by expression of plasma cell differentiation transcriptional factors, BLIMP-1 and IRF4. This article is the first to show that stem-like MCL cells utilize constitutive NF-κB expression for survival. Given that the NF-κB expression in MCL-ICs is resistant to bortezomib, it will be important to find alternative therapeutic strategies to inhibit NF-κB expression.

Visualization of Transepithelial Passage of the Immunogenic 33-Residue Peptide from α-2 Gliadin in Gluten-Sensitive Macaques

BackgroundBased on clinical, histopathological and serological similarities to human celiac disease (CD), we recently established the rhesus macaque model of gluten sensitivity. In this study, we further characterized this condition based on presence of anti-tissue transglutaminase 2 (TG2) antibodies, increased intestinal permeability and transepithelial transport of a proteolytically resistant, immunotoxic, 33-residue peptide from α2-gliadin in the distal duodenum of gluten-sensitive macaques.Methodology/Principal FindingsSix rhesus macaques were selected for study from a pool of 500, including two healthy controls and four gluten-sensitive animals with elevated anti-gliadin or anti-TG2 antibodies as well as history of non-infectious chronic diarrhea. Pediatric endoscope-guided pinch biopsies were collected from each animal's distal duodenum following administration of a gluten-containing diet (GD) and again after remission by gluten-free diet (GFD). Control biopsies always showed normal villous architecture, whereas gluten-sensitive animals on GD exhibited histopathology ranging from mild lymphocytic infiltration to villous atrophy, typical of human CD. Immunofluorescent microscopic analysis of biopsies revealed IgG+ and IgA+ plasma-like cells producing antibodies that colocalized with TG2 in gluten-sensitive macaques only. Following instillation in vivo, the Cy-3-labeled 33-residue gluten peptide colocalized with the brush border protein villin in all animals. In a substantially enteropathic macaque with “leaky” duodenum, the peptide penetrated beneath the epithelium into the lamina propria.Conclusions/SignificanceThe rhesus macaque model of gluten sensitivity not only resembles the histopathology of CD but it also may provide a model for studying intestinal permeability in states of epithelial integrity and disrepair.

Study of clinical and morphological features, immunophenotype and Epstein-Bar virus infection in situ of infectious mononucleosis

To study the clinical and morphological features, immunophenotype and in situ detection of Epstein-Barr virus (EBV) infection in infectious mononucleosis (IM) to enhance the knowledge and diagnosis of the disease. Using routine haematoxylin and eosin staining, immunohistochemistry and EBER in situ hyhridization together with clinical data analysis, 15 cases of IM were evaluated for their clinical features, morphology, immunophenotype and EBV infection status. IM was common in children and young adults with a median age of 18 years. It was an acute disease with lymphadenopathy and frequently fever. Most of the patients had a rapid recovery. Every case showed a markedly T zone expansion with a mottling pattern, composing of small to large lymphocytes, plasma cells and histiocytes. The cells also showed a B-cell differentiation profile ranging from activated lymphoblastoid cells, immunoblasts, plasmablasts, plasma-like cells and plasma cells. Many small lymphocytes in the expanded T zone expressed CD3. Some of the activated lymphoblastoid cells and immonoblasts were CD20 and CD30 positive with variable intensity signals. EBER positive (nuclear staining) cells were seen in every case. The number of EBER positive cells ranged from 10 to more than 100 per high power field. These cells included small to large lymphocytes locating mostly in the expanded T zone and a few were in the follicular germinal centers. IM is an EBV related acute sell-recovering lymphoproliferative disease, having distinct clinical, morphological and immunophenotypic characteristics as well as EBV infection. Taking these features into consideration will facilitate the correct diagnosis of IM.

Sophorolipids Decrease IgE Production in U266 Cells.

RATIONALE: Sophorolipids are promising modulators of the immune response. We have previously demonstrated that sophorolipids decreased sepsis related mortality at 36 hr in vivo in a rat model of septic peritonitis by modulation of nitric oxide, adhesion molecules and cytokine production. In this study we assessed the effect of sophorolipids on IgE production to explore the anti-inflammatory effects of sophorolipid in a cellular model of allergic disease. METHODS: U266 (IgE producing myeloma cell line) were cultured in complete RPMI medium (cRPMI) +/- increasing concentrations of sophorolipids (0.1-10ug/ml) for 3 days after which levels of IgE and soluble CD23 (sCD23) protein were determined in culture supernatants (ELISA); cells were assessed for cell surface expression of CD23 and CD38 and changes in cell morphology compared with controls (cRPMI, 20% sucrose vehicle). Cell viability was determined by Trypan blue exclusion (>95%). Data are reported as mean IgE (IU/ml)+/-SE and significance between groups was determined by student's t-test. RESULTS: U266 cells cultured in cRPMI or sucrose vehicle produced high levels of IgE (520IU+/-32). Addition of sophorolipids maximally decreased IgE production at 1.0ug/ml (416+/-8SE) (p<0.01). Similar numbers of sCD23 and cell surface expression of CD23 were detected among all groups. Addition of increasing sophorolipid concentration (10ug/ml) correlated with a bimodal cell surface expression of CD38 and an increase in the percentages of plasma-like cells compared with controls (14%, 4% respectively)(p<0.05). CONCLUSIONS: Sophorolipids decrease IgE production in U266 cells, possibly through affecting plasma cell activity. This suggests that sophorolipids possess anti-inflammatory activity and may provide a novel therapy in diseases of altered IgE regulation.

Extremely Peculiar Nuclear Changes in Cultured Primary Myeloma Cells, Including Bulging and Duplication/Multiplication of Nuclei and Cell Expansion without Apparent Mitotic Forms.

Using our new cytokine-free, mitogen-free in vitro culture system for primary multiple myeloma cells (see abstract by Cohen Y and Zipori D), we have observed peculiar nuclear changes occurring during the first days in culture. After 3–4 days small lymphocytic-like cells are frequently seen, accompanied by typical plasma cells together with plasma-like cells possessing a single bulge in one edge of the nucleus (Figure 1). This nuclear bulging has been seen only in cultures from primary myeloma cases therefore it might represent a pathognomonic disease related phenomenon. Later in culture, multiple cells show nuclear bulging of variable shapes and degrees. It seems that this heterogeneity represents a spectrum of the same nuclear process (Figure 2). In addition, binucleated cells with eccentric nuclei are commonly seen at this stage, whereas multinucleated cells can be seen occasionally. Another observation is an apparent burrier-like structure between those nuclei in binucleated cells. Most interestingly, despite extensive expansion of the cultured myeloma cells (whose clonality was confirmed by FACS analysis, PCR and FISH-Bioview), mitotic forms are very rare. Furthermore, by combined FISH/morphology analysis of some cultured binucleated myeloma cells from a patient with del 13, a single signal was seen in each of the two nuclei using a probe for chromosome 13. Altogether, these unusual myeloma cell forms can now explain the yet unexplained finding frequently seen by FACS analysis of nuclear hyperploidity in myeloma cells. Currently, we use time lapse cinematography to assess the possibility that cultured myeloma cells undergo nuclear replication, through budding, and examine the possibility that these changes lead to the emergence of two daughter cells. [Display omitted]

STAT1 mediates differentiation of chronic lymphocytic leukemia cells in response to Bryostatin 1

AbstractBryostatin 1 is known to exhibit in vitro and in vivo activity against chronic lymphocytic leukemia (CLL) cells by inducing their further maturation into plasmalike cells. Signal transducer and activator of transcription (STAT) proteins play a central role in B-lymphocyte growth and function and are aberrantly phosphorylated on serine residues in CLL cells. To determine whether STAT transcription factors are important in Bryostatin 1–induced differentiation of CLL cells, primary CLL cells were examined for signaling events following exposure to Bryostatin 1 in vitro. Western analysis and electrophoretic mobility shift assays revealed that Bryostatin 1 induced tyrosine phosphorylation and DNA binding of STAT1, yet there was no effect on constitutive serine phosphorylation of STAT1. Bryostatin 1–induced STAT1 activation occurred in a manner that was dependent on protein kinase C (PKC), mitogen-activated protein kinase (MAPK), and Janus tyrosine kinase (JAK) activation. Evidence indicates that Bryostatin 1 induces STAT1 activation through an interferon γ (IFNγ) autocrine loop. However, STAT1 activation by IFNγ stimulation alone was not sufficient to induce differentiation. This insufficiency is due to the broader effect on gene expression caused by Bryostatin 1 compared with IFNγ, as demonstrated by microarray analysis. Both up-regulation of CD22 expression and immunoglobulin M (IgM) production, markers of CLL differentiation, were inhibited by a decoy oligonucleotide for STAT1, indicating that STAT1 is necessary for Bryostatin 1–induced differentiation of CLL cells. This study implicates STAT transcription factors as important mediators of Bryostatin 1–induced differentiation of CLL cells and could possibly lead to improved therapeutic approaches for the treatment of CLL.

Spontaneous increase of plasma-like cells with high GANP expression in the extrafollicular region of lymphoid organs of autoimmune-prone mice

Autoimmune-prone mice bear a hyper-active B cell population generated spontaneously in peripheral lymphoid organs. Expression of β RNA-primase GANP was shown to be an activation marker in lymphoid follicle germinal center (GC) B cells after immunization with T cell-dependent antigen (TD-Ag) in normal mice. In this study, we examined the expression of GANP in lymphoid tissues of autoimmune-prone mice. GANP expression was up-regulated in GC-B cells after stimulation with TD-Ags; however, highly GANP-positive (GANP hi) cells were also observed in lymph nodes of non-immunized MRL/lpr mice. GANP hicells in lymph nodes as well as in spleens of the different autoimmune-prone strains, MRL/lpr, NZB, (NZB×NZW)F1 and BXSB, gradually increased with age. This population was detected only in small numbers in the red pulp region of the spleen after immunization with TD-Ag in normal C57BL/6 and BALB/c mice. GANP hicells had a B220 −IgM +Syndecan-1 +phenotype, but were negative for PAS-staining and bromo-deoxyuridine incorporation. These results demonstrate that GANP hiplasma-like cells appear in lymph nodes of autoimmune mice during aging, suggesting that the new plasma cell population might be generated after hyper-activation of B cells during the course of autoimmune disease.

Gradual development of organ damage in the murine zymosan-induced multiple organ dysfunction syndrome.

A well defined animal model is a prerequisite to test intervention strategies aimed at preventing the development of the multiple organ dysfunction syndrome. This study compares changes in clinical parameters to histopathologic changes in tissues, observed over a 12 day period after a single intraperitoneal injection of zymosan in C57BL/6 mice. Administration of zymosan induced gradual and progressive changes in wet and dry organ weight of the liver, kidneys, and particularly, lungs and spleen that correlated with increasing histopathology. From 6 days after zymosan injection onwards, hemorrhagic spots were found in the lungs evolving into massive hemorrhages at 12 days, when thickened interstitial walls and loss of the honey comb-like structures were observed. The liver displayed progressive accumulation of macrophage-like and mononuclear cells. After 12 days, numerous granuloma-like structures were disseminated throughout the liver parenchyma. The spleen displayed great changes in red and white pulp with increasing numbers of megakaryocytes and plasma-like cells. In the kidneys, necrosis of the tubular epithelium adjacent to granulomas on the ventral (peritoneal) side was found. In mice, a single intraperitoneal challenge with zymosan leads to progressive multiple organ damage, which becomes apparent at some time after the insult. This animal model displays a number of features encountered in human multiple organ dysfunction syndrome and appears suitable to conduct intervention studies.

The Plasmacytoma Growth Inhibitor Restrictin-P Is an Antagonist of Interleukin 6 and Interleukin 11: IDENTIFICATION AS A STROMA-DERIVED ACTIVIN A

A stromal protein, designated restrictin-P, that specifically kills plasma-like cells was purified to homogeneity and shown to be identical with activin A. The specificity to plasma-like cells stemmed from the ability of restrictin-P/activin A to competitively antagonize the proliferation-inducing effects of interleukin (IL) 6 and IL-11. Restrictin-P further interfered with the IL-6-induced secretion of acute phase proteins by HepG2 human hepatoma cells and with the IL-6-mediated differentiation of M1 myeloblasts. A competition binding assay indicated that restrictin-P did not interfere with the binding of IL-6 to its receptor on plasma-like cells, suggesting that it may act by intervening in the signal transduction pathway of the growth factor. Indeed, concomitant addition of restrictin-P and IL-6 to cytokine-deprived B9 hybridoma cells was followed by sustained overexpression of junB gene until cell death occurred, while IL-6 alone caused a transient increase only. This altered response to IL-6 stimulation was accompanied by a moderate increase in STAT protein activation. Thus, in this study, we identified the plasmacytoma growth inhibitor, restrictin-P, as being activin A of stromal origin. It is shown that activin A is an antagonist of IL-6-induced functions and that it modifies the IL-6 signaling pattern.

A CASE OF PRIMARY PLASMOCYTOMA ARISING IN THE THYROID

We experienced a case of primary plasmocytoma arising in the thyroid. A 76-year-old female visited our hospital complaining of a tumor on the right side of the neck. The tumor locating at the posterior part of the right lobe of thyroid was 4.0×3.5 cm in size, with smooth surface, elastic hard, and well-defined border. It was mobable but slightly restricted. Ultrasonography revealed a tumor picture of irregular margin, internal unequal, and slightly unclear border. Scintigram showed a cold nodule at 99mTc and accumulated picture at 201Tl. A possible malignancy could not be denied, right thyroid lobectomy, paratracheal and parathyroidal lymph nodes dissection being done on October 1, 1990. The excised tumor was 3.8×3.5×2.4 cm in size without any infiltration into the adjacent organs. It could be easily removed. Histopathologic examination showed that the tumor consisted of plasma-like cells, leading to a diagnosis of plasmocytoma. Chronic thyroiditis could be seen in the surrounding thyroid tissues.Immunohistochemical tests resulted in positive against IgG and lambda chain. No abnormalities were noted in bone marrow puncture, general bone X-P, and bone scintigram. No urinary Bence-Jones protein nor blood M protein were determined. Only 12 cases of primary plasmocytoma arising in the thyroid, including this case, can be collected from the literature in this country.

Nonparenchymal liver cells and granulomas during lamprey biliary atresia.

Transmission (thin sections and freeze-fracture replicas) and scanning electron microscopy were used to describe the nonparenchymal liver cells during the seven (1-7) stages of metamorphosis in the sea lamprey, Petromyzon marinus L., when bile ducts and canaliculi degenerate. The biliary atresia is accompanied by an increased diameter of fenestrae in the endothelium, an active phagocytosis by Kupffer cells in the sinusoids, and large lipid inclusions in perisinusoidal lipocytes (fat-storing or Ito cells). Plasma-like cells and foci of nonparenchymal cells (granulomas) are present in the liver interstitium during at least four stages of metamorphosis. The fenestrae in the sinusoidal wall are wider (up to 2.8-micron diameter) than normally reported for vertebrate livers but are likely a reflection of the morphogenetic and physiological events and consequences of the biliary atresia. Kupffer cells are involved in an extensive erythrophagocytosis, the storage of iron, and perhaps the incorporation of cellular components from hepatocytes. Lipocytes are the vitamin A-storing cells of the transforming liver and may be responsible for some perisinusoidal fibrosis. Granulomas are present during stages 3-6 and are focal areas where mononuclear leukocytes (lymphocytes and plasmalike cells), macrophages, and neutrophils have infiltrated the hepatic parenchyma. The function of the granulomas is not known; but their presence may be related to the porous nature of the sinusoidal wall, the tissue degeneration, and/or the physiological change (e.g., bile stasis) during biliary atresia.

Induction of proliferation and differentiation of leukaemic B cells from patients with chronic lymphocytic leukaemia by anti-mu and conditioned medium.

We investigated the growth and differentiation of leukaemia B cells from patients with B-cell chronic lymphocytic leukaemia (CLL) in response to proliferation and differentiation factors present in conditioned medium and to anti-immunoglobulin antibodies. Highly purified E-rosette negative (E-) B cells from 5 out of 15 patients with CLL exhibited moderate proliferative responses to 10 or 50 micrograms/ml of F(ab)'2 fragments of rabbit anti-human mu-chain specific antibody. Conditioned medium (CM), derived by stimulating human peripheral blood mononuclear leucocytes with PHA, induced significant proliferative responses of purified E- cells in 13 out of 14 patients examined. The extent of these proliferative responses varied substantially, and was in the range of 2.6- to 91-fold. Stimulation of purified E- cells from patients with CLL with both anti-mu and CM resulted in significant proliferation in all 15 patients examined. These responses were significantly higher than those induced by CM alone (P less than 0.02). Synergism between CM and anti-mu in inducing proliferative responses was observed in 11 out of 15 patients. Largely leukaemic B cell populations expressing on the cell surface more than one immunoglobulin heavy-chain isotype, exhibited significantly higher (P less than 0.009) proliferative response to CM and anti-mu than those expressing IgM only. Highly purified E-peripheral blood or tonsil lymphocytes from all normal donors examined responded by proliferation to anti-mu alone or to CM alone. Synergism in inducing proliferative responses was also observed when the cells were stimulated with both CM and anti-mu. In addition to inducing proliferative responses, culture with CM of purified E-rosette negative, largely leukaemic, B cells from patients with CLL for 6 days at 37 degrees C resulted in differentiation into immunoglobulin synthesizing and secreting cells. Synthesis and secretion of IgM were observed in 7 out of 10 patients examined. A switch to IgG production was observed in three patients. Morphological examination of E- cells from patients with CLL after treatment with CM demonstrated that these cells were differentiated into plasma-like cells. These results suggest that leukaemic B cells from patients with CLL can be induced to proliferate and differentiate in response to growth and differentiation factors derived by mononuclear leucocytes, in a manner similar to that of normal B cells.

Spontaneous "secondary" disease in germfree AKR mice.

DISEASES which develop in gnotobiotic (germfree; mice reflect defects in the nutritional, genetic or microbial status of the host. Three viral agents have been detected so far in germfree mice, and these appear to be passed to their progeny by congenital route(s). All mouse strains carry leukaemia virus1, some strains carry mammary tumour virus2 and one strain carries lymphocytic choriomeningitis (LCM) virus3. Except for these, germfree mice are free of bacteria, fungi and parasites. They are referred to here as germfree, on the understanding that they are not free of virus. Spontaneous lymphatic leukaemia develops only in the AKR strain: in other strains (Balb/c, ICR, CFW, C3H, Swiss–Webster and C57 BL) lymphatic leukaemia must be elicited by whole body exposure to X-rays4,5. Germfree mice of the AKR strain develop the same type and incidence of spontaneous lymphatic leukaemia as the conventional stock from which they were derived. In addition, an unusual syndrome which has been referred to as “puny” disease6 has been observed in germfree AKR mice; the mice are hunched and have rough hair and dermatitis with depilation around the anus and base of the tail. Diarrhoea was difficult to assess because the faeces of germfree mice are usually semisolid in consistency. “Puny” disease has been observed in twenty-eight germfree AKR mice of average age 14 weeks. At autopsy the mice had large lymph nodes and spleens and small, almost imperceptible, thymus glands. The lymph nodes were swollen with extensive perivascular cords of lymphocytes and plasma-like cells in the medullary areas, but the prominent cortical follicles were free of germinal zones. Germinal zones were not observed in the white pulps of the spleens, but the red pulps were congested with lymphoid and plasma-like cells. The thymic cortices were depleted of thymocytes; however, in several of them, segments of the cortex contained aggregations of large reticulum cells, many in mitosis. The latter changes were suggestive of early stage thymic lymphoma, which may have been coincident with, or a sequel to, the thymic depletion.

Homologous disease in the adult rat, a model for autoimmune disease. II. Findings in the joints, heart, and other tissues.

Polyarthritis and cardiac lesions have been observed in the adult rat with homologous disease. Changes in the lymphoid tissue and kidney have also been noted. A migratory polyarthritis occurred in over half of the affected animals, and cardiac involvement of varying intensity was present in all. Histologically, the arthritis was characterized by a mononuclear synovial inflammatory reaction. In the heart, the valves and myocardium demonstrated a similar type of response. Cultures of involved joints and hearts for pyogens and pleuropneumonia-like organisms were negative. The lymphoid tissues showed progressive changes in three stages: (a) disappearance of follicles; (b) increase in plasma-like cells and histiocytes; and (c) fibrosis. The second stage tended to coincide with the development of the polyarthritis. The kidney showed mild interstitial mononuclear infiltration. The pathologic changes described appear to be a consequence of reaction between foreign immunologically competent cells and host antigens, but the possibility that these lesions represent a response to antigens derived from unknown infectious agents is, however, not ruled out.

PRIMARY MIXED CELL MYELOMA OF THE MOUTH INVOLVING THE ANTRUM

This case is reported because of the unusual pathologic picture in a primary tumor of the superior maxilla. Other cases of plasma cell tumors about the head and neck without skeletal involvement have been reported.1So far as I am aware there are but few cases of such a tumor originating about the alveolar process. Myelomas are considered most commonly to be tumors of the bone marrow which show multicentric foci of origin and produce certain characteristic roentgenologic changes in the bone involved. In addition, certain findings in the blood and urine are, as a rule, more or less commonly associated with the disease. Histologically the new growths may vary in appearance from case to case and even from point to point within the same tumor. Study of numerous sections, however, almost invariably reveals collections of plasma-like cells with eccentric nuclei, which are the most significant and pertinent factor in