Anti-CD2 (OX34) MoAb treatment of adjuvant arthritic rats: attenuation of established arthritis, selective depletion of CD4+ T cells, and CD2 down-modulation

Abstract

Anti-CD2 MoAbs have previously been shown to induce tolerance and to block B cell differentiation, T cell and monocyte activation. Since these immune functions are important in joint inflammation, we asked whether administration of the anti-CD2 MoAb OX34 has a beneficial effect on established rat adjuvant arthritis, a model of human rheumatoid arthritis, and how it affects CD2-bearing leucocyte subsets. Female Lewis rats with established adjuvant arthritis received a total of 5 mg OX34 or isotype-matched control MoAb starting on day 15 after adjuvant injection. Weight and arthritis score (AS) were measured in a blinded fashion. Peripheral blood cells were analysed for numbers of leucocyte subsets at various time points. Animals were killed on day 30 and lymphatic organs were processed for immunohistology. Clinically, OX34 treatment led to increased body weight and reduced AS. Although OX34 binds to CD4+ and CD8+ T cells in a comparable fashion, OX34 treatment reduced CD4+ T cells, but not CD8+ T cells. Among CD4+ T cells CD45RC+ ('naive') T cells virtually disappeared; CD45RC- ('recently activated') T cells were slightly reduced. A reduction of CD4+ T cells was also found in the lung, liver, bone marrow, spleen and lymph nodes. Down-modulation of the CD2 molecule by OX34, again, affected CD4+ T cells, suggesting a specific signal for CD4+ but not CD8+ T cells. In conclusion, the anti-CD2 MoAb OX34 attenuates established rat adjuvant arthritis. In spite of similar binding to CD4+ and CD8+ T cells, OX34 depletes only CD4+ T cells and down-modulates the CD2 molecule on these cells. These results suggest a therapeutic benefit from CD2-directed therapy for chronic types of arthritis.

Role of T lymphocytes in rat 2,4,6-trinitrobenzene sulphonic acid (TNBS) induced colitis: increased mortality after gammadelta T cell depletion and no effect of alphabeta T cell depletion

“…The following depleting mAbs were used in vivo: OX34 (IgG2a), directed at CD2 (depletes T helper cells),17 18 OX38 (IgG2a), directed at CD4 (depletes T helper cells),19 both kindly provided by AN Barclay (University of Oxford, UK), R73 (IgG1), directed at the rat αβ TCR (depletes αβ T cells),20 21 and V65 (IgG1), directed at the rat γδ TCR,21 both kindly donated by T Hünig (University of Würzburg, Germany). Mouse mAbs directed at epitope 1 of human CD58 AICD58.6 (epitope 1 of domain 1, IgG2a) and TS2/9 (epitope 1 of domain 1, IgG1) served as controls 22.…”

“…To determine localisation and phenotype of different cell types a immunohistochemical staining technique was used as previously described employing the APAAP method17 using the following antibodies: R73 (αβ T cells), V65 (γδ T cells), and OX8 (CD8 + T cells and NK cells) (kindly provided by AN Barclay, Oxford, UK). The slides were counterstained and mounted in glyceryl ( D akopatts, Hamburg, Germany).…”

“…The number of stained cells/mm 2 mucosa was determined in four different sections. Splenic lymphocytes were counted as previously described on two sections per animal and are expressed as number of lymphocytes within the periarteriolar lymphocyte sheath (PALS)/mm 2 of the spleen 17. Percentages of lamina propria lymphocytes or lymphocytes expressing αβ or γδ T cells were calculated using these values.…”

“…Splenocytes and peripheral blood lymphocytes were obtained by intracardial puncture or splenectomy and homogenisation as previously described 17. Single cell suspensions were exposed to hypotonic solution to lyse erythrocytes.…”

Initiation and perpetuation of rat adjuvant arthritis is inhibited by the anti-CD2 monoclonal antibody (mAb) OX34

“…We previously reported on the anti-inflammatory effects of an anti-CD2 mAb OX34 in established AA 10. This mAb was found to deplete transiently CD4 + but not CD8 + T cells.…”