Do HCAbs arise in the context of Th1 or Th2?

SACCODOSSI, NATALIA; DE SIMONE, EMILIO; LEONI, JULIANA

Buenos Aires

Congreso; 1st. French-Argentine Congress. LVIII Reunión Anual de la SAI; 2010

Sociedad Argentina de Inmunología (SAI)

Do HCAbs arise in the context of Th1 or Th2?Saccodossi, Natalia1; De Simone, Emilio A.2; Leoni, Juliana1.  1IDEHU (CONICET-UBA), Cátedra de Inmunología. Facultad de Farmacia y Bioquímica, UBA. 2Cátedra de Fisiología Animal. Facultad de Ciencias Veterinarias, UBA.  The camelids are susceptible to diseases and infections similar to those who have cattle, sheep and pig. In the latter species the role of cytokines in triggering a Th1 or Th2 response is well studied in order to develop rational vaccination plans. There are three fractions of IgG in camelids namely IgG1, IgG2 and IgG3, of which IgG2 and IgG3 are heavy chain antibodies (HCAbs). HCAbs lack the light chains and the CH1 constant domain. Currently, nothing is known about the behavior of the camelid PBMC in response to the challenge with different Ags. The objectives of this work are: to study the response of different IgG subisotypes against various antigenic stimuli, in vitro and in vivo, and to evaluate the cytokine profile predominating in each case. Three llamas were immunized with ovoalbumin (OVA) and the supernatant of a lysate of T. cruzi (F105). Total serum IgG was titrated by ELISA and greater OD readings were obtained with the sera of llamas immunized against OVA than the sera of llamas immunized with F105. Furthermore, in vitro cultures with the PBMC of immunized llamas were challenged with the Ags used in the immunization plans. After 24 hours of culture, Th1 and Th2 cytokines were evaluated by RT-PCR. There were no differences in relation to Th2 cytokines. In contrast, the challenge with F105 generated an increase of IL-2 and IFN-γ. After 6 days of culture, the response of the different fractions of IgG was evaluated by ELISA. It was noted that the supernatant of the PBMC cultured with F105 secreted IgG2. Then, we analyzed the relation between HCAbs/IgG1 against F105 in the sera of animals from different places. IgG2/IgG1 ratio was greater in the animals that had higher total IgG titers. From these preliminary results we suggest that IgG2 is related with Th1 responses. These results provide possible design objectives for future vaccines as well as criteria for detecting Th1 and Th2 immune response bias in camelids.