Rowley & Powell: I should have waited a day before commenting on the “social immunity in ants” paper.1, 2 , 3 I referred to a review in BioEssays,4 but the latest issue of the Journal of Immunology has a review with a very similar theme. 5

My comment on the original paper was basically that they refer to “immunity” and “immune priming” without actually examining any immunological functions. Quoting Hauton and Smith:

The failure to make assessment of immunological parameters is a consistent weakness in most papers purporting to demonstrate priming, memory or adaptivity in the invertebrate innate immune system. In some cases, only single-end points are taken and the role of the immune system is inferred but not actually tested.

The J Immunol review from Rowley and Powell surveys the recent literature on invertebrate immune responses. As with Hauton and Smith, they’re not much impressed by most of the claims (“Whether these observations prove the existence of an analogous adaptive immune system with levels of specificity and memory with equivalent status to that in jawed vertebrates is still very much unanswered”). They are a little more convinced, though, especially by a recent paper that Hauton and Smith didn’t specifically mention6 although even here they’re clearly not swept off their feet:

Although such specific protection could also be found for other pathogens such as the entomopathogenic fungus Beauveria bassiana, rather surprisingly (and perhaps worryingly) the other bacteria tested yielded no enhancement in protection against later challenge.

They also review possible mechanisms for immune memory in invertebrates (assuming it does exist) and propose methods to test these mechanisms (as well as explaining what isn’t acceptable): “What is surely needed is the ability to unequivocally prove the existence of immune mechanisms in selected invertebrates that both yield a memory component and have specificity in their mode of action.” This is exactly what Hauton and Smith call for, as well.

  1. Social Prophylaxis: Group Interaction Promotes Collective Immunity in Ant Colonies. Line V. Ugelvig and Sylvia Cremer. Current Biology 17:1967-1971 (20 November 2007) []
  2. I am experimenting with a citation aggregator; the next footnote should include the same reference formatted for the aggregator.[]
  3. Ugelvig, L.V., Cremer, .S. (2007). Social Prophylaxis: Group Interaction Promotes Collective Immunity in Ant Colonies. Current Biology, 17, 1967-1971.[]
  4. Hauton, C., and Smith, V. J. (2007). Adaptive immunity in invertebrates: A straw house without a mechanistic foundation. Bioessays 29, 1138-1146. []
  5. Rowley, A. F., and Powell, A. (2007). Invertebrate Immune Systems Specific, Quasi-Specific, or Nonspecific? J Immunol 179, 7209-7214. []
  6. Sadd, B. M., P. Schmid-Hempel. 2006. Insect immunity shows specificity in protection upon secondary pathogen exposure. Curr. Biol. 16: 1206-1210. []