MIAMI BEACH, Fla. (AP) _ Mike McCallum of Jamaica retained his World Boxing Association junior middleweight title Saturday by stopping Julian Jackson of the U.S. Virgin Islands in the second round.

Following them, Colombia's Miguel ''Happy'' Lora was scheduled to defend his World Boxing Council bantamweight title against Enrique Sanchez of the Dominican Republic. Lora was 24-0 with 12 knockouts, while Sanchez was at 43-3 with 31 knockouts.

In what was billed as ''the Caribbean War'' between McCallum and Jackson, McCallum knocked him down with a left jab early in the second round and after the eight-count, moved in to finish Jackson off.

McCallum peppered him with punches against the rope, allowed him to escape, then pinned him against the ropes again.

Jackson couldn't put up any resistance, and referee Eddie Eckert stepped in to stop the fight at 2:03 of the second rund.

McCallum, now 27-0, hadn't made a defense since retaining the WBA title July 28, 1985, with an eighth-round knockout of Dwight Braxton in Miami. Jackson lost for the first time after 29 wins.

Lora had fought only once since first winning the World Boxing Council bantamweight title Aug. 9, 1985, with a unanimous decision over Daniel Zaragoza of Mexico. Lora retained his title Feb. 8 with a unanimous decision over Wilfredo Vasquez, but his right eye was swollen shut and his cocky attitude took quite a shot in that bout.