I did an analysis via CellPhoneDB (CPDB) package and I am wondering how can I limit the results to cell surface proteins?

This is the dats's head:

> colnames(cpdb)
 [1] "id_cp_interaction"   "interacting_pair"    "partner_a"           "partner_b"           "gene_a"             
 [6] "gene_b"              "secreted"            "receptor_a"          "receptor_b"          "annotation_strategy"
[11] "is_integrin"         "Interacting_cell"    "Relevance"           "Cell_a"              "Cell_b"             
[16] "Mean"                "Zscore"              "Mean_scaled"      





> head(cpdb, n=1)
  id_cp_interaction interacting_pair     partner_a     partner_b gene_a gene_b secreted receptor_a receptor_b
1   CPI-SS0DE0A486F       NRP1_VEGFA simple:O14786 simple:P15692   NRP1  VEGFA     TRUE       TRUE      FALSE
  annotation_strategy is_integrin                          Interacting_cell Relevance               Cell_a
1             curated       FALSE Fibroblast_Cluster 1|Fibroblast_Cluster 2     0.749 Fibroblast_Cluster 1
                Cell_b  Mean       Zscore Mean_scaled
1 Fibroblast_Cluster 2 0.749 -0.000276821   0.3723209