In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: A group of patients with long - surviving mismatched kidney allografts were investigated for complement function using haemolytic assays in agarose gels .
### Output Text:
A group of patients with long - surviving mismatched kidney allografts were investigated for complement function using haemolytic assays in agarose gels . 