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Epidemiological, microbiological and clinical characteristics of 14 episodes of Xanthomonas maltophilia bacteremia in 12 seriously immunocompromised hematological patients, admitted to Rigshospitalet in Copenhagen over the 3-year period 1989-91, were evaluated. The results were compared with a randomly selected control group of 25 patients with Escherichia coli bacteremia. Hospital acquired bacteremia was more common among the patients with X. maltophilia bacteremia (p < 0.01). Treatment with broad-spectrum antibiotics before the bacteremic episode was markedly more common among the patients with X. maltophilia bacteremia (p < 0.001). The presence of a central venous catheter and previous treatment with corticosteroids were more frequent in patients with X. maltophilia bacteremia (p < 0.05). The X. maltophilia blood culture isolates were generally resistant to aminoglycosides and most beta-lactams. The mortality rates related to bacteremia caused by X. maltophilia and E. coli were 14% and 20%, respectively.

Among 128 patients with malignant B-lymphoproliferative disorders, 19 patients had long lasting dyspepsia and gastroscopy showed chronic active gastritis or gastric ulcer. PCR analysis for TCR and IgH clonality in biopsies showed local involvement of the malignant lymphocyte clone in four patients out of eight indicating presence of these cells in the inflammatory infiltrate. Weak B-cell clonality was found in four patients. A close relationship was seen between lymphocytic clonality and immune response to H. pylori Cag A, and all patients had parietal cell antibodies. Thus, the malignant clone may participate in the local inflammatory reaction, and continued local stimulation by H. pylori as well as parietal cell antigens may lead both to autoimmunity as well as a clonal development of lymphocytes.

Subcutaneous lesions were seen in three of 13 neutropenia patients who had Stenotrophomonas (Xanthomonas) maltophilia bacteraemia. The characteristic clinical presentation resembled leukaemic infiltrates, and were different from deep ulcers or subcutaneous nodules caused by Pseudomonas aeruginosa. The three patients had acute leukaemia and were treated with intensive combination chemotherapy. All had previously been treated with broad-spectrum antibiotics, and each patient recovered after proper combination antibiotic treatment given according to sensitivity testing.

In 18 cases of monoclonal gammopathy of undetermined significance, MGUS (monoclonal gammopathy of undetermined significance), admitted for diagnosed or suspected peripheral neuropathy, 11 patients showed other co-existing autoimmune manifestations. Two had POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-component, and skin symptoms), the others mainly endocrinopathy and polyclonal pseudolymphoma. There were 13 cases of sensorimotor neuropathy, two cases of neuritis, while neuropathy could not be confirmed in three cases. Compared with a retrospective review of autoimmunity in a randomly selected CLL (chronic lymphocytic leukemia) cohort of 115 patients, 13 out of 42 patients with clinical and/or laboratory features of autoimmunity showed co-expression of autoimmune signs, the dominating traits being Coombs positive AIHA (auto-immune hemolytic anemia), platelet autoantibodies, endocrinopathy mainly associated with the thyroid gland, serological and/or rheumatological symptoms, but only one case of sensorimotor neuropathy. Viewed from a current model of acquired autoimmunity it is perhaps not surprising that such autoimmunity is seen predominantly in patients with monoclonal gammopathy. Thus, a high concentration of cross-reacting polyreactive autoantibodies related to the M-component might be present in these patients. Furthermore, quantitative defects of the immunoglobulins including the hypogammaglobulinemia associated with M-components can presumably give rise to a defect of the anti-idiotypic network's regulation of natural autoantibodies and autoimmune manifestations in vivo. Such autoimmune manifestations, which are easily overlooked in CLL may call for additional treatment with immunosuppression and/or intravenous, polyclonal IgG.

2 cases of malignant T-lymphoproliferative disease are reported. The proliferating cell was a large blast expressing E and Fc gamma receptors but no helper or suppressor phenotypes and no SmIg. Skin infiltrates were the dominant clinical sign with conspicuous perivascular aggregations of T, E, Fc gamma lymphocytes, though both patients initially had disseminated disease with mild lymphadenopathy, splenomegaly and, in case 2, also hepatic infiltrations. Accordingly, DNA measurements on skin biopsies, taken early in the course, showed a dominating hypotetraploid clone (case 1) and a pronounced population in S-phase (case 2). The patients were alive for 6 and 2 yr, respectively, with a final fatal course of about 6 months duration involving a rather sudden progression of the skin infiltrates, increasing lymphadenopathy and splenomegaly, leukaemic transformation of the neoplastic T, E, Fc gamma lymphocyte and practically no response to cytostatic treatment.

Rothia dentocariosa is part of the human oral flora and has only rarely been reported as a cause of clinical infection. We report the isolation of Rothia dentocariosa from the blood of a septicaemic patient with chronic lymphocytic leukaemia and bone marrow depression following treatment with clomipramine and zuclopentixol.

Agarose gel electrophoresis of serum from the eleventh case of mu-chain disease (mu-CD) showed two distinct abnormal bands due to free light chains and kappa-complexes with other serum proteins. This caused diagnostic difficulties on conventional immunoelectrophoresis, and crossed immunoelectrophoresis with intermediate gel is demonstrated as a superior tool for investigation of mu-CD. A simple rocket immunoelectrophoresis method foe mu-CD screening is also shown. The mu-CD protein had alpha-2-mobility and a part of the protein carried kappa-determinants probably due to secondary binding. Preparative ultracentrifugation and size chromatography on serum demonstrated that the mu-CD protein was present in serum in several sizes, the smallest being a dimer of mu-chains. Due to scarcity of material the abnormal protein could not be characterized further.

Polyclonal intravenous IgG (IVIG) was administered as an infusion 6 times every 3 weeks (week 0, 3, 6, 9, 12, 15) in doses of 0.1, 0.4 and 0.8 g/kg BW to determine the dose causing an increase in 12 pneumococcal antibody types above the protective level of 200 ng/ml of antibody N. The dose of 0.4 g/kg BW was found to be optimal in patients with chronic lymphocytic leukaemia (CLL). From the first infusion onwards at least 80% of CLL patients had increases in all 12 antibodies. Five weeks after the last infusion the antibody levels were still elevated in 80% of patients with CLL. The dose of 0.8 g/kg raised all 12 antibodies in 53-73% of CLL patients when assessments were made after each infusion. In multiple myeloma (MM) patients, 73-82% and 73-91% of patients had increased antibody levels, respectively, before and after the 4th-6th infusions at the 0.8 g/kg dose level. However, in only 45-50% of patients did the antibodies remain increased 2 weeks after the treatment at this dose. The dose of 0.4 g/kg caused antibody increases in only 30-50% of patients when measured before the 4th-6th infusion. Serum IgG increased significantly only in the CLL patients, whereas in the MM patients it was high from the beginning owing to the disease. Therefore, the pneumococcal antibody levels were a better marker for the purpose of dose finding. The dosage recommendation in CLL is 0.4 g/kg every 3 weeks until week 12, when steady state is reached. The maintenance dose is 0.4 g/kg every 5 weeks. In MM patients, who have a faster elimination rate of antibodies, the recommended loading dose is 0.8 g/kg, followed by 0.4 g/kg every week as a continuous treatment. Treatment with IVIG in CLL and MM was generally well tolerated. Only 25% of patients experienced minor side-effects, the most frequent being febrile reactions, shivering and headache.