ANDROGEN AND ESTROGEN-RECEPTORS ARE PRESENT IN PRIMARY CULTURES OF HUMAN SYNOVIAL MACROPHAGES

Macrophages, as antigen-processing and -presenting cells to T lymphocy tes, play a key role in the immune system and are suspected to be targ et cells of the sex hormone-related dimorphism in the immune response peculiar to rheumatoid arthritis (RA) pathology. In the present study, the use of specific monoclonal antibodies revealed immunostaining for androgen and estrogen receptors in primary cultures of macrophages ob tained from synovial tissues of patients affected by RA and controls w ithout RA disease. Soluble and nuclear type I (high affinity, low capa city) and type II (lower affinity, greater capacity) sites of androgen or estrogen binding were detected in primary cultures of RA macrophag es using radioligand binding assay. Higher levels of type I and type I I estrogen receptor compared to those of androgen receptor were found, particularly in the soluble fraction; however, contrary to what was o bserved in whole synovial tissues, higher steroid receptor concentrati ons were found in the soluble than in the nuclear fraction of RA synov ial macrophages. Binding affinities and receptor contents of cultured synovial macrophages were comparable to those previously reported in o ther well established sex hormone-responsive cells and tissues. Furthe r, specific messenger ribonucleic acids for sex hormone receptors, enc oding for a sequence of the DNA-binding domain of the receptor protein s were revealed by RT-PCR.