Use the CellItem property to retrieve the item's handle. Use the ItemCell property to gets the cell's handle given an item and a column. Most of the properties of the Items object that have parameters [Item as Variant], [ColIndex as Variant], could use the handle of the cell to identify the cell, instead the ColIndex parameter. For instance the following statements are equivalents:

With ComboBox1.Items
    .CellCaption(.FocusItem, 0) = "this"
    .CellCaption(, .ItemCell(.FocusItem, 0)) = "this"
End With

Note: The intersection of an item with a column defines a cell. Each cell is uniquely represented by its handle. The cell's handle is of HCELL type, that's equivalent with a long type. All properties of Items object that have two parameters Item and ColIndex, refer a cell.

The following lines are equivalents and each of them changes the bold font attribute of the first cell on the first item.

With ComboBox1
    .Items.CellBold(, .Items.ItemCell(.Items(0), 0)) = True
    .Items.CellBold(.Items(0), 0) = True
    .Items.CellBold(.Items(0)) = True
    .Items.CellBold(.Items.ItemByIndex(0)) = True
    .Items.CellBold(.Items.ItemByIndex(0), 0) = True
    .Items.CellBold(.Items(0), ComboBox1.Columns(0).Caption) = True
End With