Positivity of lepromin reaction (LR) was often said to be increased after leprosy skin lesions were improved by chemotherapy. But there were no special reports dealing with long term observation of LR in the same patients.
This study in Kuryu-Rakusenen concerned the 248 in-patients, whose clinical records were relatively complete and who were followed for more than 20 years. And the LR by standard Mitsuda antigen was tested covering 20 years (every year between 1957 and 1969 and each other year between 1970 and 1977). The following results were obtained.
1. Thirty three tuberculoid patients showed slight increase in LR during these 20 years (r=0.58).
2. There were also slight increase in lepromatous patient during these 20 years (p<0.05). Three groups were divided in relation to the bacteriological status in 1957 and 1977. A very few patients in the group, which were bacteria-positive in 1957 and same in 1977, gave over 7mm in LR in 1977. But other two lepromatous groups indicated significant increase in LR in 1977 (p<0.05) ; one of the two groups was bacteria-positive in 1957 and bacteria-negative in 1977, and another was bacterianegative in 1957 and same in 1977.
3. There was no significant relation between bacterio-negative time and LR in 1977 (r=0.288). But there was significant increase of positivity in LR of the group which showed over 16 years in bacteria-negative time. However we must give attention to the six lepromatous cases with negative LR whose bacteria-negative time was over 16 years.
4. The lepromatous patients with over 7mm LR in 1977 could be said to have eye brows and to have no episode of ENL (p<0.01). It seems that these patients may have the element of borderline leprosy.
5. The lepromatous patients, who were bacteria-negative and over 7mm in LR, had few relapses with skin lesions or without skin lesions. Erickson reported subclinical relapse in 1951. It is considered that our relapse cases without skin lesions were subclinical, because these cases had no real relapses. The relapses with skin lesions were found within three years. It could be said that the quiescent lepromatous patients with over 7mm in LR will have no episode of relapse after three years (p<0.01).
