A monoclonal antibody, 3G12, reacts with a novel surface molecule, Hal-1, with high expression in CD30-positive anaplastic large cell lymphomas.

We established a monoclonal antibody, 3G12 (IgG1), with antiproliferative effects on a human T-cell leukaemia cell line, SUP-T13. Among haematolymphoid cell lines, 3G12 reacted with most T-cell lines, Epstein-Barr transformed B-cell lines, some myelomonocytic cell lines and, most strongly with an anaplastic large cell lymphoma (ALCL) cell line, Karpas 299. The cell panel reactive with 3G12 was similar, but not identical, to that of the anti-CD30 antibody Ber-H2. 3G12 induced Fas-independent apoptosis in SUP-T13 and it also induced growth-inhibition in a limited number of other cell lines, but not Karpas 299. Immunohistochemical studies on paraffin-embedded tissue specimens demonstrated that 3G12 reacted with most CD30-positive ALCL cases and some T-cell lymphomas and some Hodgkin's lymphomas, but not with B-cell lymphomas or non-haematogeneic tumours. The immunoprecipitation study with 3G12 demonstrated a major band of 200 kD and a minor band of 100 kD, which were different from CD30. Thus 3G12 defines a novel antigen that shares a similarity to CD30 in terms of distribution among haemopoietic cells. The data suggest that the 3G12-defined antigen, designated Hal-1, is important as a marker for ALCL and may play a role in its pathogenesis.