No abstract

We have investigated the effect on sensitization of altering the area of application of 2,4,dinitrochlorobenzene (DNCB) at a constant dose per unit area. We showed that, when an area of less than 1 cm2 is used, this area is critical in determining the degree of sensitization. This contrasts with previous work that showed, for larger areas, an alteration in the area of application had little effect on sensitization, whereas keeping the area constant and increasing the concentration of DNCB increased the degree of sensitization. We suggest that not only is the amount of antigen important in determining response, but also the distribution of the antigen as presented to the afferent limb of the immune system.

We have investigated the differences between the sexes in the development of contact sensitivity induced by dinitrochlorobenzene (DNCB). Ten male and 12 female subjects were sensitized with DNCB (30 micrograms applied on a 1 cm patch test disc) and challenged 1 month later with doses of 8.8, 12.5, 17.7 and 25 micrograms. The responses were measured after 48 h as increase in skinfold thickness with Harpenden callipers. Females showed a larger response at all challenge doses studied, and the slope of the log-dose response curve was significantly steeper in females. We conclude that there are significant differences in delayed type hypersensitivity between males and females.

SUMMARYWe examined theeflfecis ofa small itiitial sensitizing dose of antigen (dinitrochlorobenzene, DNCB) on the subscqucnl response to a second, defined sensitizing stimulus. The second stimulus was actually the regimen of four doses of DNCB (3-125,6-25,12'5, and 25 /jg; total 46-9 fig) normally used as the elicitation challenge. In two separate experiments Band 18 control subjects received an initial 'challenge' with the four doses to induce sensitivity, and 4 weeks later their responses were determined with a second, elicitation challenge. Two groups of 12 and 15 experimental subjeets received an inital dose predicted to induce clinically detectable sensitivity in 50% or 25%, respectively. Four weeks later, their responsiveness was determined with quantitative challenge and the subjects who gave no response received a further challenge 4 weeks later. Their responses, eompared with those from the control subjects, were augmented, indicating thai sub-clinical priming of the immune system had indeed occurred.

No abstract