Memory T Lymphocytes Generated by Mycobacterium bovis BCG Vaccination Reside within a CD4 CD44lo CD62 Ligandhi Population

In the lungs of mice vaccinated with Mycobacterium bovis BCG, there was an accumulation of CD4 cells expressing the activated effector phenotype CD44hi CD62 ligandlo (CD62Llo) which were capable of secreting gamma interferon. Upon cell transfer, however, cells expressing a resting/naive phenotype (CD44lo CD62Lhi) were capable of protecting the recipients from a virulent challenge infection, suggesting the emergence of T-cell memory from within this subset.