α-Hemoglobin-stabilizing protein is a sensitive and specific marker of erythroid precursors.

α-Hemoglobin-stabilizing protein (AHSP) is an abundant erythroid-specific chaperone protein that facilitates incorporation of nascent α-globin into hemoglobin A. We characterized AHSP expression by immunohistochemistry in a panel of 100 neoplastic and reactive bone marrow biopsies and splenic tissue with extramedullary hematopoiesis and compared it with established erythroid markers CD71 and CD235a. In all cases, AHSP expression was limited to physiological nucleated erythroid precursors (EPs) and blasts in erythroid leukemias. Although CD71 also stained EPs, it additionally stained nonerythroid malignant cells to varying extents in acute leukemia, diffuse large B-cell lymphoma, metastatic carcinomas, and small round blue cell tumors. In contrast, CD235a staining was erythroid-specific but stained non-nucleated red blood cells in all specimens, limiting its utility. We conclude that AHSP is superior to CD71 and CD235a for detecting normal and neoplastic nucleated EPs.

Presentation of hemophagocytic lymphohistiocytosis due to a novel MUNC 13-4 mutation masked by partial therapeutic immunosuppression.

Hemophagocytic lymphohistiocytosis is a potentially fatal disease characterized by excessive macrophage and lymphocyte activity. Patients can be affected following immune activation after an oncologic, autoimmune or infectious trigger. An associated gene mutation may be found which impairs cytolytic lymphocyte function. We describe a pediatric case of hemophagocytic lymphohistiocytosis with a novel mutation of MUNC 13-4 whose diagnosis was confounded by concurrent immunosuppression. Clinical reassessment for hemophagocytic lymphohistiocytosis is necessary in persistently febrile patients with laboratory derangements in the setting of immunosuppressive agent exposure.

B lymphocyte-directed immunotherapy promotes long-term islet allograft survival in nonhuman primates.

We found that an induction immunotherapy regimen consisting of rabbit anti-thymocyte globulin (Thymoglobulin) and the monoclonal antibody to CD20 rituximab (Rituxan) promoted long-term islet allograft survival in cynomolgus macaques maintained on rapamycin monotherapy. B lymphocyte reconstitution after rituximab-mediated depletion was characterized by a preponderance of immature and transitional cells, whose persistence was associated with long-term islet allograft survival. Development of donor-specific alloantibodies was abrogated only in the setting of continued rapamycin monotherapy.

Disseminated Mycoplasma orale infection in a patient with common variable immunodeficiency syndrome.

Human infection with Mycoplasma species other than M. pneumoniae are infrequent, but may be encountered in patients with immunodeficiencies. We report a patient with combined variable immunodeficiency that developed multiple abscesses and destructive bone disease caused by M. orale, an organism generally considered to be non-pathogenic. Molecular laboratory methods, 16S rRNA sequence analysis, were used to detect the organism directly in the surgical specimen and confirmed following isolating of the organism. This case demonstrates the importance of molecular technology in the diagnosis of difficult infectious disease problems.