3AE8: monoclonal antibody defining inflammatory macrophages in three species

Differences in proliferative rate and collagen lattice contraction between endotenon and synovial fibroblasts

Injured and surgically repaired tendons heal with the formation of scar tissue. Scar tissue represents 1 of the most unpredictable factors contributing to postoperative morbidity. The main cell involved in scar formation is the fibroblast. The relative activity of fibroblasts from the fibro-osseous sheath (the tissue surrounding the tendon in zone II) and the endotenon (the core of the tendon) with respect to proliferation and the ability to contract a collagen lattice were compared in vitro. The fibroblasts derived from the fibro-osseous sheath were more active in both these respects. In addition, the amount of matrix metalloproteinase activity was found to be greater for the fibro-osseous sheath fibroblasts, implying a greater capacity to degrade and disorganize connective tissue and thus migrate. These results imply that the fibro-osseous fibroblasts represent a more active population of cells compared with endotenon fibroblasts, and perhaps should be specifically targeted in future modes of therapy.

Patterns of cellular activation after tendon injury

Mechanisms which lead to disabling adhesions following flexor tendon surgery of the hand were investigated in a rabbit model which was used to assess the relative response of the cells of the synovial sheath, epitenon and the endotenon to injury. A transverse laceration, cutting through 50% of the tendon, was made just outside the synovial sheath on the flexor aspect of the flexor digitorum profundus tendon. The synovial sheath was preserved intact. Using monoclonal antibodies for localizing specific inflammatory markers, we were able to follow the response and activity of the synovial sheath, epitenon and endotenon with respect to these markers at various times after surgery. Our findings suggest that the synovial sheath and the epitenon are relatively more reactive in the early period after injury, as judged by a range of inflammatory indices with the notable exception of the expression of the potent neovascularizing agent, basic fibroblast growth factor (bFGF).

Monoclonal antibodies define the characteristics and cellular distribution of an Ia-associated protein

In a recent report we described the identification of physical associations between Major Histocompatibility Complex (MHC) Class II (Ia) antigens and other structures of Mr 67,000, which were significantly enhanced following brief T-B cell co-culture (1). To further investigate this 67K Ia-associated product, monoclonal antibodies (MAb) were produced against isolated 67K material and their reactivity examined. Cell surface binding by these MAb was detected only after perturbation of the membrane by cellular adherence or following aldehyde fixation, which indicates that the determinant recognized by these mAb is retained in the plasma membrane in a covert fashion. All lymphoid cells tested showed reactivity with the MAb as determined by immunofluorescence and by ELISA, but no binding was detected on bone marrow or peritoneal macrophages. Expression of the antigen reactive with these antibodies followed a similar pattern with established murine cell lines, with T and B cell lines and a pre-B cell line showing reactivity, while no antigen was detected on macrophage-like and fibroblast cell lines. The intensity of antigen expression by normal lymphoid cells was ordered: thymocytes greater than splenic T cells greater than or equal to bone marrow lymphocytes greater than splenic B cells. No correlation was observed between expression of Ia antigens by non-lymphoid cells and expression of the 67K molecule. These observations suggest that this antigen is primarily a marker of lymphoid cells, with the highest expression on cells of the T lymphocyte lineage. Finally, inhibition of antigen-specific, MHC-restricted T-cell activation by the MAb directed against the 67K structure suggests an important functional role for this interesting molecule originally identified by its physical association with Ia following T-B cell interactions.

The development and analysis of species specific and cross reactive monoclonal antibodies to leukocyte differentiation antigens and antigens of the major histocompatibility complex for use in the study of the immune system in cattle and other species

We examined the potential of developing a set of species specific and cross reactive monoclonal antibodies (MoAbs) for use in the study of the phylogenetic and functional relation of class I and class II antigens of the major histocompatibility complex (MHC) and leukocyte differentiation antigens in cattle and other species. Comparing immunization strategies demonstrated the number of hybrids producing cross reactive antibodies can be increased by hyperimmunization of mice with lymphoid cells from multiple species. Comparing various methods of assay (antibody-complement mediated cytotoxicity [CT], enzyme linked immunosorbent assay [ELISA] and flow microfluorimetry [FMF]), revealed FMF is the most useful technique for the primary assay of hybridomas producing MoAbs of potential interest. By using dual parameter and dual fluorescence analysis, we could determine whether a given MoAb reacted with mononuclear cells (lymphocytes and monocytes) and/or granulocytes, and also whether any two MoAbs of different isotype and specificity recognized antigens present on identical or separate populations of leukocytes. Comparing the patterns of MoAb reactivity with leukocytes obtained from cows, goats, sheep, pigs, horses and humans, as well as comparing the patterns of reactivity with a panel of lymphoid cell lines derived from cattle (with enzootic bovine leukemia) and humans (with various forms of leukemia), revealed sets of MoAbs reactive with unique antigenic determinants present on BoLA class I (15 MoAbs) and class II (9 MoAbs) antigens, and also MoAbs reactive with determinants present on leukocyte differentiation antigens (36 MoAbs). Dual fluorescence analysis demonstrated the antigens detected by some MoAbs are predominantly expressed on one lineage of leukocytes while others are expressed on two or more lineages of leukocytes. Dual and single fluorescence analysis also demonstrated the PNA receptor(s) is: expressed on T cells, granulocytes and class II antigen monocytes and absent or expressed in low amount on sIgM+ B cells and a newly defined Non T/Non B population of cells. The strategies described for identifying and analyzing the specificity of MoAbs demonstrate the feasibility of developing a set of cross reactive MoAbs for identifying homologous molecules in multiple species and delineating their functional and phylogenetic relation.