An immunogenic composition comprising (a) a first antigen, (b) polymeric particles that comprise a polymer that is at least partially biodegradable, and (c) a benzonaphthyridine compound, wherein the benzonaphthyridine is a compound having the structure of Formula (VIII), or a pharmaceutically acceptable salt thereof: wherein: R 21 is H, C 1 -C 6 alkyl, -C(R 25) 2 OH, -L 21 R 25, -L 21 R 26, -L 22 R 25, -L 22 R 26, -OL 22 R 25, or-OL 22 R 26; L 21 is -C - or -O-; L 22 is C 1 -C 6 alkylene, C 2 -C 6 alkenylene, arylene, heteroarylene or -((CR 24 R 24) p O) q (CH 2) p -, wherein the C 1 -C 6 alkylene and C 2 -C 6 alkenylene of L 22 are optionally substituted with 1 to 4 fluoro groups; each L 23 is independently selected from C 1 -C 6 alkylene and -((CR 24 R 24) p O) q (CH 2) p-, wherein the C 1 -C 6 alkylene of L 23 is optionally substituted with 1 to 4 fluoro groups; L 24 is arylene or heteroarylene; R 22 is H or C 1 -C 6 alkyl; R 23 is selected from C 1 -C 4 alkyl, -L 23 R 25, -L 21 R 25, -L 23 R 27, -L 23 L 24 L 3 R 27, -L 23 L 24 R 25,-L 23 L 24 L 23 R 25, -OL 23 R 25, -OL 23 R 27, -OL 23 L 24 R 27, -OL 23 L 24 L 23 R 27, -OR 28,-OL 23 L 24 R 25, -OL 23 L 24 L 23 R 25 and -C(R 25) 2 OH; each R 24 is independently selected from H and fluoro; R 25 is -P (OR 29) 2, R 26 is -CF 2 P (OR 29) 2 or -C OR 30; R 27 is -CF 2 P (OR 29) 2 or -C OR 30; R 28 is H or C 1 -C 4 alkyl; each R 29 is independently selected from H and C 1 -C 6 alkyl; R 30 is H or C 1 -C 4 alkyl; each p is independently selected from 1, 2, 3, 4, 5 and 6, and q is 1, 2, 3 or 4; with the proviso that when R 23 is C 1 -C 4 alkyl or -OR 28, then R 21 is -C(R 25) 2 OH,-L 21 R 25, -L 21 R 26, -L 22 R 25, -L 22 R 26, -OL 22 R 25, or -OL 22 R 26, wherein R 26 is-CF 2 P (OR 29) 2 and R 27 is -CF 2 P (OR 29) 2. R 21 is H, C 1 -C 6 alkyl, -C(R 25) 2 OH, -L 21 R 25, -L 21 R 26, -L 22 R 25, -L 22 R 26, -OL 22 R 25, or-OL 22 R 26; L 21 is -C - or -O-; L 22 is C 1 -C 6 alkylene, C 2 -C 6 alkenylene, arylene, heteroarylene or -((CR 24 R 24) p O) q (CH 2) p -, wherein the C 1 -C 6 alkylene and C 2 -C 6 alkenylene of L 22 are optionally substituted with 1 to 4 fluoro groups; each L 23 is independently selected from C 1 -C 6 alkylene and -((CR 24 R 24) p O) q (CH 2) p-, wherein the C 1 -C 6 alkylene of L 23 is optionally substituted with 1 to 4 fluoro groups; L 24 is arylene or heteroarylene; R 22 is H or C 1 -C 6 alkyl; R 23 is selected from C 1 -C 4 alkyl, -L 23 R 25, -L 21 R 25, -L 23 R 27, -L 23 L 24 L 3 R 27, -L 23 L 24 R 25,-L 23 L 24 L 23 R 25, -OL 23 R 25, -OL 23 R 27, -OL 23 L 24 R 27, -OL 23 L 24 L 23 R 27, -OR 28,-OL 23 L 24 R 25, -OL 23 L 24 L 23 R 25 and -C(R 25) 2 OH; each R 24 is independently selected from H and fluoro; R 25 is -P (OR 29) 2, R 26 is -CF 2 P (OR 29) 2 or -C OR 30; R 27 is -CF 2 P (OR 29) 2 or -C OR 30; R 28 is H or C 1 -C 4 alkyl; each R 29 is independently selected from H and C 1 -C 6 alkyl; R 30 is H or C 1 -C 4 alkyl; each p is independently selected from 1, 2, 3, 4, 5 and 6, and q is 1, 2, 3 or 4; with the proviso that when R 23 is C 1 -C 4 alkyl or -OR 28, then R 21 is -C(R 25) 2 OH,-L 21 R 25, -L 21 R 26, -L 22 R 25, -L 22 R 26, -OL 22 R 25, or -OL 22 R 26, wherein R 26 is-CF 2 P (OR 29) 2 and R 27 is -CF 2 P (OR 29) 2.