Blood defense system - Proposal for a new concept of an immune system against blood borne pathogens comprising the liver, spleen and bone marrow.

Blood-borne pathogen (BBP) infections can rapidly progress to life-threatening sepsis and must therefore be promptly eliminated by the host's immune system. Intravascular macrophages of the liver sinusoid, splenic marginal zone and red pulp and perisinusoidal macrophage protrusions in the bone marrow (BM) directly phagocytose BBPs in the blood as an innate immune response. The liver, spleen and BM thereby work together as the blood defence system (BDS) in response to BBPs by exerting their different immunological roles. The liver removes the vast majority of these invading organisms via innate immunity, but their complete elimination is not possible without the actions of antibodies. Splenic marginal zone B cells promptly produce IgM and IgG antibodies against BBPs. The splenic marginal zone transports antigenic information from the innate to the adaptive immune systems. The white pulp of the spleen functions as adaptive immune tissue and produces specific and high-affinity antibodies with an immune memory against BBPs. The BM works to maintain immune memory by supporting the survival of memory B cells, memory T cells and long-lived plasma cells (LLPCs), all of which have dedicated niches. Furthermore, BM perisinusoidal naïve follicular B cells promptly produce IgM antibodies against BBPs in the BM sinusoid and the IgG memory B cells residing in the BM rapidly transform to plasma cells which produce high-affinity IgG antibodies upon reinfection. This review describes the complete immune defence characteristics of the BDS against BBPs through the collaboration of the liver, spleen and BM with combined different immunological roles.

The human spleen as the center of the blood defense system.

Blood-borne infections can develop into sepsis and are therefore a major human health risk. The responsible pathogens thus need to be eliminated rapidly. Intravascular macrophages in the liver and bone marrow (BM) sinuses, and in the red pulp and marginal zone of the spleen, remove the majority of these microorganisms via innate immunity. However, specific antibodies are essential for their complete elimination. Splenic marginal zone B cells simultaneously produce many of the IgM and IgG2 antibodies that target blood-borne pathogens within a few days of infection. Subsequently, follicular B cells of the white pulp of the spleen produce specific IgG antibodies against the invading pathogens, known as adaptive immunity. Although the liver, BM, and spleen work together to activate the defense response to blood-borne pathogens through innate and adaptive immunity, the spleen acts as the center of the blood defense system (BDS). The structure of the spleen is introduced in this review in relation to its function in the BDS as part of the response of the immune system and of functioning organs to blood-borne pathogens. The concept of a BDS is also important for hematological disorders, such as lymphomas and; therefore, may be useful to hematologists and pathologists.

Chronic myelogenous leukaemia with a p53 mutation demonstrated neutrophilic granulocytes with nuclear hypolobation (pseudo-Pelger-Hüet anomaly) and hypogranulation in the peripheral blood smear.

A 70-year-old man visited our emergency department, whose laboratory test results revealed leucocytosis, anaemia, thrombocytopenia and high levels of serum lactate dehydrogenase. In addition, the peripheral blood smear revealed neutrophilic granulocytes with nuclear hypolobation (pseudo-Pelger-Hüet anomaly), hypogranulation and no myeloperoxidase reactivity. Genetic testing of the peripheral blood sample was as follows: G-band, 46XY,t(9;22)(q34;q11.2) (20/20); fluorescence in situ hybridisation BCR/ABL fusion signal, 97%; and analysis of exons 5-9 of the p53 gene, mutation (Pro72Arg) in exon 4 protein. On the basis of these findings, the patient was diagnosed with chronic myelogenous leukaemia (CML) in chronic phase with a p53 mutation and treated with hydroxyurea, dasatinib and nilotinib. Neutrophilic granulocytes with the anomalies were no longer observed after achieving cytogenetic remission. To the best of our knowledge, this is the first report of CML case with the anomalies, in which a p53 mutation without chromosome 17 abnormalities was identified.

Follicular lymphoma in situ in the spleen of a patient with autoimmune hemolytic anemia and carrying HCV was associated with more clonal B-cells than t(14;18) positive B-cells.

Certain autoimmune conditions are associated with an increased risk of lymphoid malignancy. We report a 65-year old patient with autoimmune hemolytic anemia (AIHA) complicated by a follicular lymphoma (FL) in situ and other B-cell clones in the spleen. This diagnosis was made by immunohistochemistry, flow cytometry, and Southern blot analysis of the B-cell receptor. Chromosomal analysis revealed 46,XX,t(14;18)(q32;q21) 2/20, 46,XX,del(7)(q?),del(11)(q?) 2/20, and 46,XX 16/20. It has been speculated that these preneoplastic conditions do not progress to overt FL and other lymphomas without a second lymphomagenic insult. However, AIHA confers a 27.4-fold higher risk of such an insult leading to lymphoma compared with the normal healthy population. Without any therapy after splenectomy, our current study patient remained healthy with no lymphoma development for 28 months. Based on this case, we discuss the pathophysiology of lymphomagenesis in a spleen with AIHA and the roles of a splenectomy for preventing further lymphomagenesis in AIHA patients.

A multicenter clinical study evaluating the confirmed complete molecular response rate in imatinib-treated patients with chronic phase chronic myeloid leukemia by using the international scale of real-time quantitative polymerase chain reaction.

Achievement of complete molecular response in patients with chronic phase chronic myeloid leukemia has been recognized as an important milestone in therapy cessation and treatment-free remission; the identification of predictors of complete molecular response in these patients is, therefore, important. This study evaluated complete molecular response rates in imatinib-treated chronic phase chronic myeloid leukemia patients with major molecular response by using the international standardization for quantitative polymerase chain reaction analysis of the breakpoint cluster region-Abelson1 gene. The correlation of complete molecular response with various clinical, pharmacokinetic, and immunological parameters was determined. Complete molecular response was observed in 75/152 patients (49.3%). In the univariate analysis, Sokal score, median time to major molecular response, ABCG2 421C>A, and regulatory T cells were significantly lower in chronic phase chronic myeloid leukemia patients with complete molecular response than in those without complete molecular response. In the multivariate analysis, duration of imatinib treatment (odds ratio: 1.0287, P=0.0003), time to major molecular response from imatinib therapy (odds ratio: 0.9652, P=0.0020), and ABCG2 421C/C genotype (odds ratio: 0.3953, P=0.0284) were independent predictors of complete molecular response. In contrast, number of natural killer cells, BIM deletion polymorphisms, and plasma trough imatinib concentration were not significantly associated with achieving a complete molecular response. Several predictive markers for achieving complete molecular response were identified in this study. According to our findings, some chronic myeloid leukemia patients treated with imatinib may benefit from a switch to second-generation tyrosine kinase inhibitors (ClinicalTrials.gov, UMIN000004935).

Primary hepatic and hepatosplenic diffuse large B-cell lymphomas with intrasinusoidal and interstitial lymphomatous infiltration.

Primary hepatic and hepatosplenic diffuse large B-cell lymphomas (DLBCLs) are rare cancers and form nodules in most instances. However, very rare cases can diffusely infiltrate the whole liver without nodules. The general clinicopathological features of these lymphomas have not been reported to date. In our current study, we attempted to elucidate the features of these lesions through our direct observations and by reviewing the current literature. We describe the characteristics of 2 patients with hepatic and hepatosplenic DLBCL by autopsy. The lymphoma cells showed diffuse infiltration of the liver, red pulp of the spleen, and bone marrow with intrasinusoidal and interstitial lymphomatous infiltration of the organs. We discuss our observations in relation to previously reported DLBCLs with a similar pathology.

Infectious mononucleosis lymphoadenitis showing histologic findings indistinguishable from toxoplasma lymphadenitis. A report of three cases.

Lymph node lesions in infectious mononucleosis (IM) show a marked histologic diversity. We report here three cases of IM lymphadenitis with histologic findings indistinguishable from those of toxoplasmic lymphadenitis. The histologic findings of the three cases presented here showed a histologic triad of toxoplasmic lymphadenitis, including (i) numerous lymphoid follicles with hyperplastic germinal centers; (ii) small clusters or single epithelioid histiocytes; and (iii) multiple foci of monocytoid B-cells. Moreover, all three lesions contained isolated or small clusters of epithelioid histiocytes within the hyperplastic germinal centers and the periphery of lymphoid follicles, which are the most specific histologic findings of toxoplasmic lymphadenitis. However, serologic findings confirmed EBV infection in all three cases. On in situ hybridization, numerous Epstein-Barr virus (EBV)-encoded small RNA (EBER)-positive cells were demonstrated in the germinal center, as well as in interfollicular areas in all three cases. Toxoplasmosis gondii infection was excluded in at least one case, based on serologic findings. Polymerase chain reaction analysis also demonstrated that there was no T. gondii DNA in the remaining two cases. Two of our three cases showed atypical clinical presentations, including an absence of atypical lymphocytosis in peripheral blood in two cases, age more than 30 years, and an absence of systemic symptoms in one case. It appears that previous descriptions emphasize the differential diagnostic problems between IM lymphadenitis and malignant lymphomas. However, from a therapeutic perspective, it is important to discriminate IM lymphadenitis from toxoplasmic lymphadenitis particularly in patients showing atypical clinical features.

Primary splenic diffuse large B-cell lymphoma manifesting in red pulp.

We evaluated six cases of diffuse large B-cell lymphoma (DLBCL) involving the red pulp of the spleen. All had B symptoms and an aggressive clinical course. The lymphoma cells proliferated diffusely and non-cohesively in the cords of the red pulp. The lymphoma involved the bone marrow in four of the five patients and the liver in all four of the patients examined. However, lymph node (LN) involvement was rare at presentation, and systemic LN involvement was not observed even in the terminal phase. The lymphoma cells infiltrated the intrasinusoidal/intravascular and interstitial spaces of the involved tissues and were detected in the peripheral blood in two of the six patients. CD5-expressing lymphoma cells were detected in four of the five patients examined. Because these cases had some unique clinical features and occurred in distinct splenic sites, we proposed that primary splenic DLBCL manifesting in red pulp is a distinct clinicopathological entity.

Clinical implications of idiopathic multicentric castleman disease among Japanese: a report of 28 cases.

To clarify the clinicopathologic findings of idiopathic multicentric Castleman disease among Japanese, 28 cases were studied. Two variants were delineated by the clinicopathologic findings (1) idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia (n = 18) and (2) nonidiopathic plasmacytic lymphadenopathy type (n= 10). Clinicopathologically, idiopathic plasmacytic lymphadenopathy was defined by the prominent polyclonal hyperimmunoglobulinemia, normal germinal centers, and sheet-like infiltration of plasma cells in the interfollicular area of the lymph node. Histologically, the nonidiopathic plasmacytic lymphadenopathy type was characterized by hyaline-vascular germinal centers of the lymph node lesion. In comparison with idiopathic plasmacytic lymphadenopathy, patients with nonidiopathic plasmacytic lymphadenopathy showed infrequent prominent polyclonal hyperimmunoglobulinemia and frequent association with autoimmune disease. However, there was no difference in the overall 5-year survival between the 2 subtypes. Compared with idiopathic multicentric Castleman disease in Western countries, the chronic course of the disease of idiopathic multicentric Castleman disease in Japan appears to be related to negativity for human herpesvirus 8 infection.

Epstein-Barr virus-related reactive lymphoproliferative disorders in middle-aged or elderly patients presenting with atypical features. A clinicopathological study of six cases.

We report six cases of Epstein-Barr virus (EBV)-associated lymphoproliferative disorders (LPDs) in middle-aged and elderly patients exhibiting atypical clinical findings. The patients, two males and four females, ranged in age from 52 to 74 years, with a median age of 64 years. Clinically, they were characterized by tonsillar tumor, cervical lymphadenopathy, and absence of atypical lymphocytosis of the peripheral blood. "B"symptoms were recorded in only two cases. Pancytopenia was recorded in one case during the disease course. The clinical course was self-limited. Histologically, all lesions were characterized by effacement of the follicles and expansion of the interfollicular area with proliferation of small vessels, indicating atypical lymphoid proliferation. In the interfollicular area, there was a mixed infiltrate, including small-to-medium-sized lymphocytes, plasma cells, and T-and B-immunoblasts. Immunoblasts resembling Reed-Sternberg cells were observed in four lesions. Three lesions contained numerous mature plasma cells, plasmacytoid cells, and immature plasma cells in some areas. In situ hybridization demonstrated a varying number of EBV-infected lymphocytes in the interfollicular area. The overall histomorphologic findings of the present six cases were similar to those of infectious mononucleosis (IM) in younger patients. However, the clinical findings were quite different from those of IM in the younger age population. To avoid overdiagnosis and overtreatment, we emphasize the need to be aware of the atypical clinical presentation of EBV-related LPDs in middle-aged or elderly patients, and to turn careful attention to these clinical and laboratory findings as well as to the morphologic features.