Merged or Indistinguishable Spots

Symptom

Spots merge together and become indistinguishable, making it impossible to count individual cytokine-secreting cells. This results in large, confluent areas instead of discrete spots.

1. 1 Over-stimulation causing excessive cytokine/protein secretion by cells
2. 2 Prolonged cell culture exceeding 24 hours leading to excessive cytokine production
3. 3 Too many cells per well (exceeding optimal 1-2 × 10⁵ cells per well range)
4. 4 Excessive primary antibody concentration during coating step

1. 1 Reduce stimulant concentration in culture media or shorten stimulation time
2. 2 Limit cell culture incubation to maximum 24 hours
3. 3 Optimize and reduce cell number per well to 1-2 × 10⁵ cells
4. 4 Reduce primary antibody concentration during coating step

Related Video (2)

Mabtech ★ 82

ELISpot tutorial: step-by-step full assay protocol

"Full step-by-step ELISpot protocol tutorial demonstrates correct procedures and likely addresses avoiding over-stimulation/spot merging through proper cell and stimulus handling."

Animated biology With arpan ★ 68

Elispot assay ( assay to determine cytokine producing cells)

"Explains ELISpot principle at single-cell level, giving context for why discrete spots matter and how over-secretion causes confluence."