| Abstract |
In contrast to other B-cell neoplasias the immunologic phenotype of
myeloma cells is only poorly defined. Therefore we have performed an
extensive immunephenotypic analysis of 3 human myeloma cell lines
established in vitro in our laboratory (LOPRA-1 (IgA2/kappa), LOPRA-2
(IgG1/lambda), LOPRA-3 (IgG3/kappa)) by flow cytometry (FACS 440) and
immunocytochemical staining (APAP). In addition, 10 bone marrow samples of
multiple myeloma patients were phenotyped by APAP technique. The myeloma
cells were consistently negative for surface immunoglobulin and NLA class
II (NLA-DR/DP, HLA-DQ) antigens. Moreover, HLA class II antigens were not
inducible by IFN-alpha or IFN-gamma. The myeloma cells did not stain for
most B-cell differentiation antigens (CD10 (CALLA), CD19 (B4), CD20 (B1),
CD21 (B2), CD22 (HD39), CD23 (MHM6), CD37 (BL14), CD39 (G28-8)) except
PCA-1 and CD38 (OKT10). Monoclonal antibodies of the CD24 cluster gave a
heterogeneous staining pattern: Some monoclonal antibodies were
consistently negative, whereas others showed a broad reactivity peak which
may be due to posttranslational modifications of the CD24 molecule
synthesized in myeloma cells. In addition, we have employed hybridoma
technology to produce monoclonal antibodies to cell surface antigens
restricted to myeloma/plasma cells. Six antibodies detected antigens on
the immunizing myeloma cells; two of them displayed a staining pattern
restricted to late B-cell differentiation stages as analysed on a panel of
normal and neoplastic tissues.
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