T CD4+ lymphocytes are not required for the control of a second infection to P-chabaudi AS

The role of CD4(-) T lymphocytes in the specificity of the immune response to malaria was studied in a murine model. CBA/Ca mice, either normal or immune to P. chahnudi, were treated with MAb alpha-CD4, or rat IBG and then challenged with P, chabaudi. P. yoelii. or both. Among normal mice treated with IgG only those infected with P, chabaudi survived, while those without CD4(+) mortality rate was of 100%. Immune mice treated with IgG or a-CD4 controlled the homologous challenge, however CD4(+) depleted immune mice had a 100% mortality rate with the heterologous one. Therefore, CD4(+)T lymphocytes are necessary for the elimination of P, chabaudi in a primary infection. they induce the activation of specific mechanisms that do not require their presence to control a second infection with the homologous parasite. Nevertheless, to control an heterologous challenge, immune mice require the presence of CD4(+) T cells.