[Binding of natural IgM autoantibodies DJ to T-lymphocytes and T-cell hybridomas and its possible role in apoptosis].
BACKGROUND
Natural autoantibodies can recognize self-antigens expressed on damaged cell membranes and participate in their elimination from the body and maintainance of homeostasis. It has been shown earlier that human monoclonal immunoglobulin M DJ isolated from sera of patients with Waldenstrom macroglobulinemia, possesses characteristics of natural antibodies/autoantibodies and binds to phosphoryl choline. In this paper we analyzed binding of IgM DJ to the membrane of thymocytes, T-lymphocytes derived from lymph node and to T-cell hybridomas.


METHODS
Human monoclonal IgM antibodies were isolated by means of euglobulin precipitation and used for immunization of BALB/c mice. T-lymphocytes were isolated from lymph nodes and stimulated by antigen or Concanavalin A, used as a mitogen. For obtaining T-T hybridoma, fusion was done with BW 5147 cell line. Binding of IgM DJ to T-lymphocytes and T-hybridomas was detected by flow cytometry.


RESULTS
We presented IgM DJ binding to the membrane of thymocytes and lymphocytes of the lymph nodes from nonimmunized mice. Binding with similar characteristics was demonstrated for T-lymphocytes isolated from lymph nodes from immunized mice before in vitro stimulation, which significantly increased after stimulation either by mitogen or by antigen. The highest level of binding of IgM DJ was obtained in the population of in vitro cultivated lymphocytes, not stimulated in vitro. By analyzing cells which bound IgM DJ, it has been established that the examined cell population presented with characteristics of cells undergoing apoptosis.


CONCLUSIONS
These results indicate that IgM DJ can be involved in maintenance of homeostasis by elimination of cells expressing phosphoryl choline during apoptosis.
Zivancević-Simonović
Snezana
S
Inić-Kanada
Aleksandra
A
Kosec
Dusko
D
Dimitrijević
Ljiljana
L
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D017209:Apoptosis / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001666:Binding Sites, Antibody; D005260:Female; D005434:Flow Cytometry; D006825:Hybridomas / Q000276:immunology*; D007114:Immunization; D007075:Immunoglobulin M / Q000276:immunology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D013601:T-Lymphocytes / Q000276:immunology*; D008258:Waldenstrom Macroglobulinemia / Q000276:immunology
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007075:Immunoglobulin M