Downregulation of mafB expression in T-helper cells during early differentiation in vitro.

We have studied the expression of a human homologue of mafB (maf-1), a member of the family of large maf transcription factors. In support of the suggested key role that mafB expression plays in differentiating macrophages, we found mafB to be expressed at a very high level in monocytic U937 and THP-1 cell lines. However, we show here that mafB transcription is not restricted to myeloid cells but can also be detected in lymphoid cells, indicating transcriptional plasticity during haematopoiesis.

Cytokine control of interstitial collagenase and collagenase-3 gene expression in human chondrocytes.

Human collagenase-3 expression, previously seen only in a breast tumor tissue, is here shown to be expressed in primary human chondrocytes derived from the joint tissue and in transformed human chondrocytes. Its mRNA is inducible by the inflammatory cytokines interleukin-1beta plus tumor necrosis factor-alpha, but not by phorbol 12-myristate 13-acetate and only slightly by the growth factors platelet-derived growth factor and epidermal growth factor. Human synovial fibroblasts, another prominent cell type in the joint tissue, do not produce collagenase-3 message.

Molecular characterization of a 65-kilodalton Toxoplasma gondii antigen expressed abundantly in the matrix of tissue cysts.

We describe the cloning and characterization of a novel antigen expressed in the bradyzoite stage of Toxoplasma gondii. A cDNA library was constructed in bacteriophage lambda gt11 Sfi-Not using messenger RNA molecules isolated from cysts of the ME49 strain of T. gondii.

Two alleles of the gene encoding surface antigen P22 in 25 strains of Toxoplasma gondii.

A group of 25 strains of Toxoplasma gondii (4 mouse-virulent strains and 21 mouse-avirulent strains) were tested by immunoblot with 4 monoclonal antibodies (MAb) against surface antigen P22. Parasite lysates from only 12 strains were recognized by all 4 MAbs, while lysates from the remaining 13 strains (all avirulent) were not recognized by any of the 4 MAbs. Strains not recognized by the 4 MAbs were found to express an altered form of the P22 antigen.