Infectious mononucleosis: immunoglobulin synthesis by cell lines

Surface receptors on human haematopoietic cell lines

The expression of complement receptors, of Fc receptors, of SRBC receptors and of S-Ig was investigated on human haematopoietic cell lines of proved malignant derivation. According to their origin and to a panel of phenotypic markers these lines have been classified into lymphoma lines, myeloma lines and leukemia lines. Results were compared with those obtained on non-malignant EBV carrying lymphoblastoid cell lines (LCL). Among the lymphoid cell lines the LCL showed a pattern of B-lymphocyte surface markers, i.e. surface immunoglobulins, C3 receptors but low density of Fc receptors. The non-Burkitt lymphoma lines bore in varying degree these B-lymphocyte markers. The lines U-698 M and DG-75 were exceptional in having only surface immunoglobulin. The Burkitt lymphoma lines had all B-lymphocyte markers. The myeloma lines differed from the lymphoid lines in lacking C3 and Fc receptors and showed only trace amounts of surface immunoglobulins. In contrast to lymphoid and myeloma lines, the leukaemia lines were completely lacking surface immunoglobulins, but showed C3 and Fc receptors in variable densities. On line, the ALL derived line MOLT-3 showed the capacity to spontaneous rosette formation with SRBC. The findings that LCL presented a homogeneous pattern of B-lymphocyte surface markers may be of value in order to discriminate between these lines and lines derived from haematopoietic malignancies other than Burkitt lymphomas.

Infectious mononucleosis: model for self-limiting lymphoproliferation

Evidence for the extensive lymphoproliferation which characterises infectious mononucleosis (I.M.) is summarised, and some of the mechanisms which are though to control lymphoproliferative activity in this disease are discussed. The main host responses which appear to limit lymphoproliferation in I.M. include the development of humoral antibodies against the Epstein-Barr (E.B.) virus-associated membrane antigen (present on the E.B. viral envelope and on E.B.-virus-infected cells) and cellular immune responses directed against E.B.-virus-containing lymphocytes. Recent evidence is reviewed which indicates that E.B. virus preferentially infects B lymphocytes and that these E.B.-virus-containing cells, which are altered antigenically, evoke a massive response in the host T cells which do not carry E.B. virus; in the presence of E.B.-virus-infected B cells, T cells are transformed and become cytotoxic for B cells. Some of the general implications of the predominant T-cell response in I.M. are discussed with particular relation to autoantibody formation and antigenic competition. The possible role of the distinctive heterophil antigens and antibodies in determining the self-limiting course of I.M. is briefly considered. The general status of I.M. as a self-limiting, albeit intense, lymphoproliferative disease is appraised and the tenuous relationship between I.M. and irreversible lymphoproliferative states is discussed.

Human lymphoblast cell lines: antibody-dependent cytotoxicity

Five cell lines were isolated after prolonged culture of human buffy coat leukocytes. The cells consisted for the most part of lymphoblasts morphologically similar to those produced by in vivo or in vitro stimulation of small lymphocytes by antigens or mitogens. One of the lines possessed virus-like particles of the Epstein-Barr type. All the established lines were capable of mediating antibody-dependent cytotoxicity (LADC) quantitatively at a level not significantly different from that mediated by freshly isolated, normal human peripheral blood lymphocytes (PBL). The LADC of the lymphoblasts was inhibited by all the human IgG subclasses tested (IgG1, IgG2, IgG3, IgG4) as was the LADC of PBL. It is concluded that, at least so far, the lymphoblasts have retained the properties of the lymphocytes from which they were originally derived as regards their ability to mediate LADC.

A method for the storage and retrieval of laboratory data on human lymphoblastoid cell lines

A computer-based system has been developed for the handling and retrieval of data on long-term human lymphoblastoid cell lines. It permits accurate recording of a wide range of genetic markers and other defined characteristics for the donor of each culture and for individual aliquots of any cell line. The data is recorded in relation to the in vitro age of each aliquot studied and the programme is designed to permit both the sequential examination of a single cell line and the comparison of lines of different origins. It is hoped that, by the application of this type of system, the confusion which has arisen in relation to other long-term cell lines (and which threatens to develop in relation to human lymphoblastoid cell lines) may be avoided and that the exchange of information between laboratories may be facilitated.

Lambda-chain production in human lymphoblast-mouse fibroblast hybrids

Mutant human lymphoblast cells deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) activity were hybridized with thymidine kinase (EC 2.7.1.21)-deficient mouse fibroblasts. Hybrid cells were readily selected, as both parental lines were nonreverting and eliminated by hypoxanthine-amethopterinthymidine medium. Human lambda (lambda) chain was the only immunoglobulin chain produced by the lymphoblast parent, as determined by immunofluorescent techniques. Two independent hybrid clones chosen for detailed study synthesized human lambda chain, and continued to do so after prolonged culture. As in both parental lines, no human immunoglobulin heavy chains, complements C3 or C4, or alpha(1)-antitrypsin, or mouse immunoglobulin chains or complement C5 were detectable in the hybrids. Selection against thymidine kinase-containing hybrid cells with 5-bromodeoxyuridine did not eliminate positive lambda-chain reactivity, suggesting that the kinase and lambda-chain loci are not linked. The continued production of an immunoglobulin chain by human lymphoblast-mouse fibroblast hybrids contrasts with the extinction of other differentiated functions in several hybrid systems, and indicates that gene localization and linkage analysis for human immunoglobulin chains should be feasible with this system.

Products of lymphoid cells in continuous culture

Images