Previous studies on T cell activation via CD43 antigen stimulation were limited to the use of L10, a monoclonal antibody (mAb) recognizing a sialic acid-independent epitope on the CD43 molecule. Here we study the CD43 mAb MEM-59, which recognizes a neuraminidase-sensitive epitope on the CD43 molecule, for its ability to activate T lymphocytes. The antibody by itself is able to stimulate proliferation of peripheral blood mononuclear cells (PBMC) in a monocyte-dependent fashion, and to act synergistically with the mitogen phorbol 12-myristate 13-acetate. It is demonstrated that the monocyte dependence of MEM-59-induced proliferation of peripheral blood lymphocytes (PBL) cannot be attributed to cross-linking via Fc receptors on monocytes alone: F(ab')2 fragments of MEM-59 are at least as effective as intact IgG in the induction of PBMC proliferation. The effects of MEM-59 reported here are distinct in important ways from those reported for L10. Our proliferation data are extended by the observation that MEM-59 mAb induces mobilization of intracellular Ca2+ in PBMC and in the T cell line Jurkat, while the CD3/TcR-negative Jurkat derived-mutant J.TR3-T3.5 exhibits defective signaling compared to the parent cell line. Moreover, CD3 and CD43 are shown to be present jointly in a large complex in a mild detergent lysate of the T cell line HPB-ALL. These data indicate a physical and functional association between CD3/TcR and CD43 pathways, suggesting a role for CD43 as a co-stimulatory molecule in CD3/TcR signaling, especially in T cell-antigen-presenting cell interactions.

Paroxysmal nocturnal haemoglobinuria (PNH) is now generally accepted as a disease in which bone marrow derived cells are deficient in phosphatidylinositolglycan (PIG)-anchored surface molecules. A series of new monoclonal antibodies detecting PIG-anchored surface structures on human leucocytes (CD48, CD55, CD59) has recently been described. In the present study 12 patients with the diagnosis PNH and a positive Ham test were examined for PIG-anchored surface antigen expression on various cell lineages using immunofluorescence. In all patients deficient cells were detected in erythrocyte, granulocyte and monocyte analysis. A deficient lymphocyte subset was also observed in all but one of these patients. Using two-colour analysis, all lymphocyte subpopulations such as T, B and NK cells were found to be affected. In addition, peripheral blood cells of 22 patients with severe aplastic anaemia (SAA) were tested for the PIG-anchoring defect. In five of these patients the defect was detected, and in four of the five the lack of PIG-anchored molecules was confined to the granulocyte and monocyte lineages apparently without affecting the erythrocytes. The results of these studies demonstrate that cytofluorographic testing of peripheral blood cells provides a simple and reliable method for establishing the diagnosis of PNH. Furthermore, especially in the case of aplastic anaemia patients, the sensitivity of immunophenotyping might be superior to conventional laboratory tests.

In this randomised prospective study we investigated whether treatment results of maximal androgen blockade (MAB) in patients with metastatic prostatic cancer can be further improved by additional Methotrexate therapy (MTX). A total number of 61 patients (stage T1 or '1"2) have been included and 31 were randomised to arm A receiving MAB, i.e. orchiectemy + flutamide (3x250 rag/d). In group B 30 patients were treated with MAB + 50 mg{m 2 MTX (once weekly for 4 months). 53 patients are evahiable for response criteria.