A combination of a source of a CD39 (ENTPD1) and a source of a CD73 for use as a medicament for preventing, delaying, curing, reverting and/or treating rheumatoid arthritis and wherein: a. the source of a CD39 comprises: i) a CD39 protein, a CD39 polypeptide, a CD39 peptide, or a CD39 protein fragment of at least 50 amino acids, wherein the source of a CD39 has at least 95% sequence identity with any one of SEQ ID NO: 1, 5, 9 and 11 and having nucleoside triphosphate diphosphohydrolase activity; and/or ii) a nucleic acid molecule encoding the CD39 protein or polypeptide or peptide or protein fragment as defined in claim 1a.i) having nucleoside triphosphate diphosphohydrolase activity, and wherein the source of a CD39 is able to convert adenosine triphosphate to adenosine diphosphate and adenosine monophosphate; and b. the source of a CD73 comprises i) a CD73 protein, a CD73 polypeptide, a CD73 peptide, or a CD73 protein fragment of at least 50 amino acids, wherein the source of a CD73 has at least 95% sequence identity with any one of SEQ ID NO: 3, 7, 13 and 15 and having ecto-nucleotidase activity; and/or ii) a nucleic acid molecule encoding the CD73 protein or polypeptide or peptide or protein fragment as defined in claim 1b.i) having ecto-nucleotidase activity, and wherein the source of a CD73 is able to convert AMP to adenosine. a. the source of a CD39 comprises: i) a CD39 protein, a CD39 polypeptide, a CD39 peptide, or a CD39 protein fragment of at least 50 amino acids, wherein the source of a CD39 has at least 95% sequence identity with any one of SEQ ID NO: 1, 5, 9 and 11 and having nucleoside triphosphate diphosphohydrolase activity; and/or ii) a nucleic acid molecule encoding the CD39 protein or polypeptide or peptide or protein fragment as defined in claim 1a.i) having nucleoside triphosphate diphosphohydrolase activity, and wherein the source of a CD39 is able to convert adenosine triphosphate to adenosine diphosphate and adenosine monophosphate; and i) a CD39 protein, a CD39 polypeptide, a CD39 peptide, or a CD39 protein fragment of at least 50 amino acids, wherein the source of a CD39 has at least 95% sequence identity with any one of SEQ ID NO: 1, 5, 9 and 11 and having nucleoside triphosphate diphosphohydrolase activity; and/or ii) a nucleic acid molecule encoding the CD39 protein or polypeptide or peptide or protein fragment as defined in claim 1a.i) having nucleoside triphosphate diphosphohydrolase activity, and b. the source of a CD73 comprises i) a CD73 protein, a CD73 polypeptide, a CD73 peptide, or a CD73 protein fragment of at least 50 amino acids, wherein the source of a CD73 has at least 95% sequence identity with any one of SEQ ID NO: 3, 7, 13 and 15 and having ecto-nucleotidase activity; and/or ii) a nucleic acid molecule encoding the CD73 protein or polypeptide or peptide or protein fragment as defined in claim 1b.i) having ecto-nucleotidase activity, and wherein the source of a CD73 is able to convert AMP to adenosine. i) a CD73 protein, a CD73 polypeptide, a CD73 peptide, or a CD73 protein fragment of at least 50 amino acids, wherein the source of a CD73 has at least 95% sequence identity with any one of SEQ ID NO: 3, 7, 13 and 15 and having ecto-nucleotidase activity; and/or ii) a nucleic acid molecule encoding the CD73 protein or polypeptide or peptide or protein fragment as defined in claim 1b.i) having ecto-nucleotidase activity, and