Table 1.

Lysosomal enzyme activity in cell lysates

Enzyme	nmol/h/mg cell protein		Microglia activity/macrophage activity
	Macrophage activity	Microglia activity
Tripeptidyl peptidase (TPP) I	50	238	4.74
Cathepsin B	56	80	1.44
Dipeptidyl peptidase (DPP) I	1915	7242	3.78
Cathepsin H	563	472	0.84
DPP II	16	79	5.05
Cathepsin D	51	147	2.88

The assay media were buffered as follows: cathepsin D, pH 3.5; TPP I, pH 4.5; cathepsin B, DPP I and DPP II, pH 5.5; and cathepsin H, pH 6.8.