Table 2.

Summary of characteristic features positively expressed (+), negatively expressed (−) and negative with scattered positive expression (−/S +) in ICs compared with primary AT2 cells and the type 1 cell line (TT1).

Techniques	AT2	TT1	HAEL-1	HAEL-2	HAEL-3	HAEL-4	HAEL-5	HAEL-6	HAEL-7	HAEL-8	HAEL-9	HAEL-10	HAEL-11	HAEL-12
Gene expression
RAGE	−	+	+	+	+	+	+	+	+	+	+	+	+	+
Caveolin-1	−	+	+	+	+	+	+	+	+	+	+	+	+	+
SP-C	+	−	+	+	+	+	+	+	+	+	+	+	+	+
WBs
RAGE	−	+	+	+	+	+	+	+	+	+	+	+	+	+
Caveolin-1	−	+	+	+	+	+	+	+	+	+	+	+	+	+
Podoplanin	−	+	+	+	−	+	+	+	+	−	+	+	+	+
SP-C	+	−	+	+	+	+	+	+	+	+	+	+	+	+
ICC
Podoplanin	−	+	+	+	+	+	+	+	+	+	+	+	+	+
Alkaline phosphatase activity	+	−	−/S +	−/S +	−	−	−/S +	−/S +	−/S +	−/S +	−/S +	−/S +	−/S +	−
TEM
Membrane invaginations	-	+	+	+	+	+	+	+	+	+	+	+	+	+
Apical microvilli	+	−	−/S +	−/S +	−	−/S +	−	−	−	−	−	−	−/S +	−/S +
Tight junctions	+	−	−	−	−	−/S +	−	−	−	−	−	−	−/S +	−/S +
Lamellar Bodies	+	−	−/S +	−/S +	−	−/S +	−	−	−	−	−/S +	−/S +	−/S +	−/S +

Gene expression data and data on the ultrastructure of AT2 cells were obtained respectively from Johansson et al.²⁸and Bingle et al.⁶.