BTW... your lymphocytes won't adhere. All the cells will settle to the bottom of the well, but that doesn't mean the cells are adhered to the plate. So... unless you are using adherence to get rid of lymphocytes, just keep that in mind.
Sorry not possible from this image. You need a much better phase contrast photo that will show nuclear shape and cytoplasmic granularity. A smear fixed and stained with Giemsa or another simple stain used for evaluating blood cell types would be best.
Did you use supplemented RPMI-1640 (e.g. L-glutamine, Na-pyruvate, non-essential AA, antibiotics and FCS) and plate at a density of 1 x 106 cells/mL? I suppose these cells are PBMCs, however the pic resolution is not good or you seeded >1 x 106 cells/mL.
The picture not clear, but from references as aperipheral blood mononuclear cell (PBMC) is any blood cell having a round nucleus such as lymphocyte, monocyteor amacrophage. So, its PBMC