an instruction thereon which would have resulted in a waiver of the defense by reason of the respondents’ failure to request such an instruction. Hogan, 840 S.W.2d at 235; Hopkins, 673 S.W.2d at 469. However, the appellants, relying on Bosworth, maintain that even if the affirmative defense of the running of the statute of limitations was not waived by the respondents by their failing to request an instruction thereon, they successfully avoided the statutory bar of the statute by reason of a pleaded exception thereto. We disagree. In order for the appellants to avail themselves of the Bosworth exception to the statute of limitations, the court held that they were required to and did specifically plead it. Id. at 777-78; see also Angoff v. Mersman, 917 S.W.2d 207, 211 (Mo.App.1996) (<HOLDING>). The failure to so plead results in the waiver
recognizing that mitigation of damages is an affirmative defense a party must plead and prove holding that the plaintiff waived an objection to the defendants failure to plead qualified immunity as an affirmative defense holding that to avoid an affirmative defense  a plaintiff must plead specifically matters of affirmative avoidance pursuant to rule 5508 holding that sudden emergency is an affirmative defense which must be specifically plead holding that a claim of exemption is an affirmative defense which must be specifically pleaded