An approach to the biological properties of HCAbs

NATALIA SACCODOSSI, EMILIO DE SIMONE AND JULIANA LEONI.

Rio de Janeiro, Brasil

Congreso; 13th International Congress of Immunology; 2007

ALAI

13 International Congress oi Immunology, Rio do Janeiro, Brazil, Aug 21-25, 2007 MS-14.3 An approach to the biological properties of HCAbs N. Saccodossi, E. De Simone, J. Leoni; IDEHU (CONICET)-UBA. Ciudad de Buenos Aires, Argentina.   Part of the circulating y immunoglobulins ofthe camelids are heavy chain antibodies (HCAbs) devoid of light chains and the CH'l constant domain. There are three subclasses of IgG in dromedaries and llamas namely |gG1, |gG2 (|gG2a, |gG2b and |gG2c) and |gG3, of which |gG2 and IgG3 are of the HCAbs type. The objectives of this work are: to study the cDNA organization of the HOAbs and the convenhonal classes ofAbs, and to analyze the relation between the HCAbs and the T helper (TH) cytokines in llama glama. Full cDNA constant regions were obtained from the llama y2a, y2b and y2c HCAbs which revealed conserved motifs related to effector functions. We could also amplify by RT-PCR IgA and IgM heavy chain constant regions which have not been described in camelids yet. Subsequently, we studied the in vitro expression ofthe TH1 and TH2 cytoquines by RT-PCR against different antigens. Peripheral blood mononuclear cells were cocultured with proteins of T. cruzi and OvoAIb which revealed a TH2 phenotype; and superantigens, LPS and ConA which revealed a THl phenotype. The relation between these TH phenotypes and the IgG isotypes is being analyzed. In parallel, we have done flow cytometric analysis to characterize B-cells populations using antisera against: IgG1, HCAbs, Iglvl, and the light chains. The structure and the relation between the HCAbs and the TH cytokines are interesting ways to look for some of the biological properties of the HCAbs.