Histoanalytical study of the cellular infiltrate in the tuberculin reaction

In contrast to the generally held view, in previous studies it has been found that the histopathological changes in delayed-type hypersensitivity reactions to intradermal purified protein derivative of tuberculin (PPD) in humans were not uniform. These were classified into three types based on their resemblance to features seen in other dermatoses, i.e.: (i) perivascular dermatitis type; (ii) basal spongiotic dermatitis type; and (iii) erythema multiforme type. These histopathological patterns correlated well with the clinical response seen in tuberculin hypersensitivity of tested subjects. In the present study, the immunohistopathological features in 44 skin biopsy specimens were assessed quantitatively by using multivariate analysis. The numbers of infiltrating cells in the epidermis and in the dermis which were immunohistologically positive to monoclonal antibodies against various mononuclear cells were counted separately to determine if there was any statistical correlation between the histopathological patterns and the phenotypes of infiltrating cells. As a result, a significant correlation was found between the histopathological patterns and the phenotypes of cells infiltrating the epidermis, such as CD8+ cells, CD4+ cells, CD11c+ cells and interleukin 2 receptor positive cells. All these cells showed a high correlation coefficient to the expression of HLA-DR antigen by keratinocytes. Next, factors that might regulate the inflammation and interaction among the infiltrating cells were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)