I want to quantify how many "green" cells also express a "red" marker. This seems to be easy to quantify by overlay (for example with the Mander's coefficient), but I am having a hard time because green and red markers, although expressed in the same cells do not colocalize in the same cell compartment, so they do not fully colocalize. The result is that with Mander's coefficient, I feel that I am underestimating the real proportion of green cells that also express the red marker (because the maximum M value I get in a cell/group of cells that express both markers is approximately M1=0.5 when I consider that as full match). Can anyone suggest another way of measuring marker overlay?
PS: There is no way, in which I can just count the cells as positive or negative because they form long membrane processes and it is difficult to distinguish which nucleus a cytoplasm/membrane corresponds to; they form a mesh.