This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Interleukin secreted by macrophages, stimulating lymphocytes is: 
Select and explain. 
A. IL-1, B. INF alpha, C. TNF alpha, D. IL-6
A: IL-1
Answer: A: IL-1 
Explanation: Macrophages release IL-1 which stimulates the T-helper cells.
The T-cells in response proliferate and release IL-2 which in turn stimulates still further T-cell proliferation and B cell proliferation and differentiation into plasma cells.

Thus

Macrophages release→IL-1*
T-helper cells release→ IL-2*