Effect of interleukin-1 alpha on the growth of Mycobacterium microti within J774A.1 cells

The effect of mouse recombinant interleukin-1 alpha on the intracellular growth of Mycobacterium microti in a murine macrophage cell line J774A.1 was investigated. Interleukin-1 alpha added after infection to the M. microti-infected macrophage monolayers enhanced the growth of M. microti in a concentration-dependent manner and this growth enhancement was abrogated by neutralization of interleukin-1 alpha with anti-interleukin-1 alpha antibody. Cyclic adenosine monophosphate level in J774A.1 cells was increased by the addition of interleukin-1 alpha. Addition of dibutyryl cyclic adenosine monophosphate to infected J774A.1 cells increased the number of intracellular bacteria in a concentration-dependent manner. These results suggest that interleukin-1 alpha acts as a growth enhancer for intracellular M. microti and the growth enhancing effect of interleukin-1 alpha may be due to enhanced cellular cyclic adenosine monophosphate level.