Hematopoietic neoplasm coexpressing CD4 and CD56 includes a subset of acute myeloid leukemia with myelomonocytic differentiation, plasmacytoid monocyte tumor, and other immature hematopoietic neoplasms of undefined origin. Herein, we report a CD4+CD56+CD68+ hematopoietic tumor that was thought to be a tumor of plasmacytoid monocytes. This case is unique in the absence of accompanying myelomonocytic leukemia and the faint expression of cCD3 on the tumor cells. The patient was a 22-yr old man presented with multiple lymphadenopathy and an involvement of the bone marrow. Tumor cells were large and monomorphic with an angulated eosinophilic cytoplasm of moderate amount. Nuclei of most tumor cells were eccentric and round with one or two prominent nucleoli. Rough endoplasmic reticulum was prominent in electron microscopic examination. Tumor cells expressed CD4, CD7, CD10, CD45RB, CD56, CD68, and HLA-DR and were negative for CD1a, CD2, sCD3, CD5, CD13, CD14, CD20, CD33, CD34, CD43, CD45RA, TIA-1, S-100, and TdT. cCD3 was not detected in the immunostaining using paraffin tissue, but was faintly expressed in flow cytometry and immunostaining using a touch imprint slide. T-cell receptor gene rearrangement analysis and EBV in situ hybridization showed negative results. Cytochemically, myeloperoxidase, Sudan black B, and alpha naphthyl butyrate esterase were all negative.
Adult ; Antigens, CD/*biosynthesis ; Antigens, CD3/*biosynthesis ; Antigens, CD4/*biosynthesis ; Antigens, CD45/biosynthesis ; Antigens, CD56/*biosynthesis ; Antigens, Differentiation, Myelomonocytic/*biosynthesis ; Bone Marrow Cells/pathology ; Cell Nucleus/pathology ; Eosinophils/metabolism ; Flow Cytometry ; Gene Rearrangement ; Humans ; Immunohistochemistry ; In Situ Hybridization ; Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis/*metabolism ; Lymph Nodes/pathology ; Male ; Microscopy, Electron ; Monocytes/*metabolism ; Receptors, Antigen, T-Cell/metabolism

Blockade of signal 1 or 2 for T-cell activation by the use of anti-CD45RB and anti-CD154 monoclonal antibodies (mAb) (two-signal blockade) has been proven effective in preventing or delaying graft rejection. However, the mechanisms of its immunomodulatory effects are clearly unknown and the present studies were performed to determine how the two-signal blockade modulate allogeneic immune responses, especially T-cell mediated cellular immunity, in a murine skin allograft model. We now report on the profound inhibition of alloreactive T cells by two-signal blockade via CD4-dependent mechanisms. C57BL/6 mice of BALB/c skin allograft were treated with anti-CD45RB, anti-CD154, CTLA4-Ig, or their combinations. For depletion of CD4 or CD8 T cells, the recipients received CD4-depleting or CD8-depleting mAb. We confirmed that survival of skin allograft was markedly prolongated in the two-signal blockade-treated group. In depletion study, anti-CD45RB, anti-CD154 and CD4-depleting mAb-treated group showed acute rejection of skin allograft in contrast to CD8-depleting group treated with the two-signal blockade. In the group treated with the two-signal blockade, the proportions of CD4+CD45RB(low)and CD8+CTLA-4 regulatory T cells were increased while effector CD8+ T cells, including IFN-gamma-secreting and CD8+CD62L(low)T cells, were decreased when compared with non-treated group. In contrast, the CD4-depleted group treated with the two-signal blockade resulted in recovery from immunoregulatory effects of two-signal blockade. In addition, results of IL-4 and IL-10 production were also showed CD4-dependence. Therefore, the two-signal blockade is accompanied by CD4-dependent mechanisms in allogeneic skin transplantation.
Transplantation, Homologous ; T-Lymphocytes, Regulatory/cytology/immunology ; Skin Transplantation/*immunology ; Signal Transduction/drug effects/immunology ; Mice, Inbred C57BL ; Mice, Inbred BALB C ; Mice ; Male ; Lymphocyte Depletion ; Lymphocyte Activation/immunology ; Interleukin-4/biosynthesis ; Interleukin-10/biosynthesis ; Graft Rejection/*immunology/prevention & control ; Flow Cytometry ; Cytotoxicity, Immunologic/immunology ; CD8-Positive T-Lymphocytes/cytology/immunology/metabolism ; CD40 Ligand/*immunology ; CD4-Positive T-Lymphocytes/cytology/immunology/metabolism ; Antigens, CD45/*immunology ; Antigens, CD4/*immunology ; Antibodies, Monoclonal/administration & dosage/*pharmacology ; Antibodies, Blocking/administration & dosage/pharmacology ; Animals