CD33 and idiopathic pulmonary fibrosis: Percentages in T signaling cells [CD4 + CTLA4 +], [CD4 + CTLA4 + CD28 +], [CD8 + CTLA4 +] and [CD8 + CTLA4 + CD28 +] in IPF patients were also noted as well as an increase in percentage of [CD33 +] monocytes in IPF patients (Fig. 6D and Additional file 2).