Treatment of post-transplant lymphoproliferative disease with induction chemotherapy followed by haploidentical peripheral blood stem cell transplantation and Rituximab.

Management of monoclonal lymphoproliferative disease following stem cell transplantation is difficult and previous attempts to eradicate tumor using chemotherapy or radiation therapy alone have not been successful. We report successful early eradication of an EBV negative, B cell non-Hodgkin's lymphoma in a child who received a T cell-depleted, maternal haploidentical bone marrow transplant for severe combined immunodeficiency disease. Our treatment strategy involved combining conventional induction chemotherapy with re-transplantation using the paternal donor as a source of peripheral blood stem cells, followed by treatment with anti-CD 20 monoclonal antibody (Rituximab). This strategy exploits the potential graft-versus-tumor activity of the mature T cells in the graft, while providing a source of stem cells to confer long-term immune function. The administration of Rituximab in the early post-transplant course may provide additional anti-tumor activity without affecting the new stem cell compartment.

Lymphoid aggregates in bone marrow mimic residual lymphoma after rituximab therapy for non-Hodgkin lymphoma.

Rituximab is a novel anti-CD20 monoclonal antibody used in the treatment of relapsed low-grade non-Hodgkin lymphoma. To determine the impact of this therapy on the interpretation of posttherapy specimens, we reviewed the pretherapy and posttherapy bone marrow and peripheral blood morphologic and flow cytometric findings for 20 patients who received rituximab. Nine patients had a total of 13 posttherapy bone marrow specimens; all were positive for lymphoma before therapy. After therapy, 11 of 13 posttherapy bone marrow specimens were interpreted as positive or suggestive of lymphoma based on routine H&E-stained sections. However, immunohistochemical and/or flow cytometric immunophenotyping showed that 6 of the 11 cases were negative for lymphoma; the lymphoid infiltrates were composed entirely of T cells without B cells. We report that posttherapy bone marrow specimens from patients treated with rituximab may mimic residual lymphoma if examined by morphologic features alone. Familiarity with this finding and the use of ancillary immunophenotypic studies will aid in the accurate interpretation of posttherapy specimens.

Nucleotide responses of human neutrophils.

Since human polymorphonuclear neutrophils (PMN) exposed to ATP or its poorly hydrolyzable analogue, adenosine-5'-O-(3-thiotriphosphate) (ATP gamma S), respond with increases in intracellular calcium and enhanced O2- responses to the chemotactic peptide N'-formyl-Met-Leu-Phe (fMLP), we systematically evaluated responses of PMN to various nucleotides. The P2X and P2Y receptor agonists, 2-methylthioadenosine triphosphate and beta, gamma-methyleneadenosine triphosphate, failed to induce increases in intracellular calcium and did not desensitize PMN to increases in intracellular calcium induced by ATP gamma S. Since it has been suggested that P2Z receptor occupancy with the ATP4- species caused nonselective increases in cell permeability, the ability of ATP to induce increases in intracellular calcium was evaluated in the presence and absence of extracellular Ca2+ and Mg2+. In the presence of these cations, 5-fold greater concentrations of ATP were required. The effects of ATP4- were not associated with changes in cell membrane permeability. This suggests that ATP4- is the active species but that its effect on PMN is not linked to a nonselective increase in permeability of the cell membrane. With respect to responses of PMN to purine and pyrimidine nucleotides as defined by increases in intracellular calcium, the rank order of potency for the nucleotides was ATP = UTP greater than ATP gamma S greater than or equal to ITP greater than GTP greater than or equal to CTP. These responses were blocked by pretreatment of PMN with pertussis toxin. Prior exposure of PMN to ATP gamma S blocked cellular responses (calcium increases) to these nucleotides but not to fMLP. Likewise, exposure of PMN to any nucleotides blocked subsequent cellular responses to ATP gamma S but not to fMLP. These data support the concept that nucleotide responses of PMN utilize either a common receptor or a common signal transduction pathway involving a guanine nucleotide binding protein in events leading to elevations in intracellular calcium. Nucleotide interaction with PMN does not follow the established pattern of responses associated with P2X or P2Y purinergic receptor occupancy.

Effects of adenosine on inositol 1,4,5-trisphosphate formation and intracellular calcium changes in formyl-Met-Leu-Phe-stimulated human neutrophils.

In the presence of adenosine, formyl-Met-Leu-Phe-stimulated human neutrophils show a greatly diminished production of superoxide anion. Analysis of changes in levels of intracellular calcium revealed that the immediate increase (occurring within seconds) in intracellular calcium following addition of formyl-Met-Leu-Phe is not affected by the presence of adenosine, although there are significantly lower intracellular calcium levels during the late phase (occurring 1-4 min after addition of formyl-Met-Leu-Phe). Consistent with these findings is the fact that adenosine does not affect the production of inositol 1,4,5-triphosphate in formyl-Met-Leu-Phe-stimulated neutrophils. These data suggest that the profound inhibitory effects of adenosine on superoxide responses in formyl-Met-Leu-Phe-stimulated neutrophils may be related to an action of adenosine occurring late in the sequence of events of signal transduction.