[The morphological characteristics of HIV-associated tuberculosis in relation to blood CD4+ lymphocyte counts]

To investigate the morphological features of HIV-associated tuberculosis with different peripheral blood CD4 lymphocyte counts.

Intraoperative and biopsy specimens from 148 patients with HIV-associated tuberculosis were examined. Group 1 included 16 (10.8%) patients having a CD4+ lymphocyte count above 350 cells/μl; Group 2 comprised 38 (25.7%) patients having 200 to 349 cells/μl; Group 3 consisted of 94 (63.5%) patients with a CD4+ lymphocyte count below 200 cells/μl. Histological and immunohistochemical studies and a polymerase chain reaction assay were used.

According to the predominant inflammatory phase, all analyzed cases were divided into 4 patterns of tissue responses: 1) typical productive granulomatous tuberculous inflammation; 2) obscure productive granulomatous inflammation; 3) a predominant alterative phase with the formation of pyonecrotic foci; 4) a predominant exudative tissue response with the development of amorphofunctional pattern typical of nonspecific inflammation. A relationship was found between the count of CD4+ lymphocytes and the predominant pattern of a tissue inflammatory response. A productive component of inflammation prevailed in Group 1; a mild productive response with the significantly obscure features of a granulomatous process was dominant in Group 2; alterative phenomena were noted in Group 3. Most patients (n=132, 89.2%) were stated to have an obscure granulomatous response (n=61, 41.2%), and a preponderance of an alternative (n=48, 32.4%) and vascular (n=23, 15.6%) components of inflammation.

The magnitude of alterative and exudative components in the foci of tuberculous inflammation suggested that there was a change-over from a delayed hypersensitivity reaction that was typical of tuberculosis to an immediate hypersensitivity reaction and reflected severe immune system dysfunction.