V{beta}6-bearing T cells are involved in resistance to Trypanosoma cruzi infection in XID mice

BALB.xid mice, carrying an X-linked mutation leading to theabsence of CD5⁺ B cells, are highly resistant to Trypanosomacruzi Infection. These mice clear blood parasites In the acutephase of infection and do not develop the inflammatory Infiltrationcharacteristically observed in the chronic phase of susceptiblestrains of mice. We have shown that the resistance of BALB.xldIs dependent on the production of high levels of IFN-y. Natural(adoptive foster) or artificial (In vivo Injection of blockingantibodies) treatments of BALB.xld induced deletion of CD4⁺and CD8⁺ cells bearing V_ß6 TCR. The absence of V_ß6lymphocytes considerably reduced resistance to infection. Furthermore,in BALB.xld lacking this minor fraction of the T cell repertoire,almost 50% of the IFN-y production is lost. This indicates thatV_ß6-bearing T cells are either directly or Indirectlyinvolved in the production of IFN-y and, thus, important foran effective immune response during the acute phase of experimentalChagas' disease.