EFFECT OF IN-VIVO DEPLETION OF CD4-CELLS ON EXPERIMENTAL-INFECTION OFSUSCEPTIBLE BALB( T)C MICE WITH LEISHMANIA-AMAZONENSIS/

The role played by CD4+ T lymphocytes in susceptible BALB/c mice infec ted with Leishmania amazonensis was investigated. Depletion of CD4+ T cells was achieved in experimentally infected mice by means of treatme nt with anti-CD4 monoclonal antibody (mAb), resulting in significant r eductions in the size of lesions and in mortality when compared with c ontrol animals. Moreover, the parasite load in the depleted mice, as q uantified by limiting dilution analysis, was about 10-times lower than in the control groups. In addition, the incidence of metastases in th e depleted mice was significantly reduced, and their appearance delaye d as compared to the control animals. These effects correlated with a selective depletion of CD4+ T cells in the spleens of the mAb-treated mice, suggesting a role for CD4+ T cells in the aggravation of L. amaz onensis infection in BALB/c mice.