Differences in Reactivity Associated with Sex or Strain of Inbred or Random-bred Guinea Pigs in the Massive Hemorrhagic Reaction and Other Manifestations of Delayed Hypersensitivity

Abstract

Male and female guinea pigs of the random-bred Hartley strain and the inbred histocompatible strains 2 and 13 were compared with regard to their reactivity in delayed type hypersensitivity phenomena. Reactivity was generally quantitated by determination of the minimum amounts of Mycobacterium tuberculosis necessary for inducing sensitization. Hartley guinea pigs were only slightly more susceptible to tuberculin sensitization than the inbred strains. For threshold sensitization, the requirements were of the order of 0.1 to 0.2 micrograms of killed dried M. tuberculosis in all 3 strains; for sensitization leading to moderate or severe reactions, 1 microgram was sufficient in Hartley guinea pigs, between 1 and 5 micrograms in Strain 13 males, and close to 5 micrograms in Strain 13 females and Strain 2 males and females. For inducing of sensitivity manifested by the hemorrhagic reaction, the following threshold doses of M. tuberculosis were determined: In male Strain 2 guinea pigs up to 2.5 mg; in female Strain 2 animals, 0.075 mg; in male Strain 13, up to 2.5 mg, in females, 0.1 mg. These requirements are all much greater than those for the male Hartley guinea pigs (0.02 mg) determined in previous investigations. In the inducing of allergic encephalomyelitis, using an excess of all the sensitizing materials, including 2.5 mg of M. tuberculosis, male Hartley guinea pigs were as susceptible as or more susceptible than male strain 13 guinea pigs, which in turn were much more susceptible to the disease than male strain 2 guinea pigs (10 deaths in 10 strain 13, 2 deaths in 10 Strain 2). The significance of these strain and sex differences in terms of the use of these guinea pigs in delayed hypersensitivity research is discussed.